Transcriptome analysis reveals the potential mechanism of the response to scale insects in Camellia sasanqua Thunb.

BACKGROUND: Camellia sasanqua Thunb. is an essential woody ornamental plant. Our continuous observation found that scale insects often infest C. sasanqua all year round in Kunming, China, resulting in poor growth. Scientifically preventing and controlling the infestation of scale insects should be paid attention to, and the mechanism of scale insects influencing C. sasanqua should be used as the research basis. RESULTS: The scale insect was identified as Pseudaulacaspis sasakawai Takagi. We analyzed transcriptome sequencing data from leaves of C. sasanqua infested with scale insects. A total of 1320 genes were either up-regulated or down-regulated and differed significantly in response to scale insects. GO (Gene Ontology) annotation analysis showed that the pathway of catalytic activity, binding, membrane part, cell part, and cellular process were affected. KEGG (Kyoto Encyclopedia of Genes and Genomes) pathway analysis showed that most DEGs (differentially expressed genes) involved in plant hormone signal transduction, MAPK signaling pathway, flavonoid biosynthesis, tropane, piperidine and pyridine alkaloid biosynthesis. We also observed that the expression of galactose metabolism and carotenoid biosynthesis were significantly influenced. In addition, qRT-PCR (quantitative real-time PCR) validated the expression patterns of DEGs, which showed an excellent agreement with the transcriptome sequencing. CONCLUSIONS: Our transcriptomic analysis revealed that the C. sasanqua had an intricate resistance strategy to cope with scale insect attacks. After sensing the attack signal of scale insects, C. sasanqua activated the early signal MAPK (mitogen-activated protein kinase) to activate further transcription factors and Auxin, ET, JA, ABA, and other plant hormone signaling pathways, ultimately leading to the accumulation of lignin, scopolin, flavonoids and other secondary metabolites, produces direct and indirect resistance to scale insects. Our results suggested that it provided some potential resources of defense genes that would benefit the following resistance breeding in C. sasanqua to scale insects.

Exploring the impact of plant growth-promoting bacteria in alleviating stress on Aptenia cordifolia subjected to irrigation with recycled water in multifunctional external green walls.

BACKGROUND: Rapid urbanization and population growth exert a substantial impact on the accessibility of drinking water resources, underscoring the imperative for wastewater treatment and the reuse of non-potable water in agriculture. In this context, green walls emerge as a potential solution to augment the purification of unconventional waters, simultaneously contributing to the aesthetic appeal and enjoyment of urban areas. This study aims to optimize water management in green walls by investigating the impact of bacterial strains on the biochemical properties and performance of the ornamental accumulator plant, Aptenia cordifolia, grown with various unconventional water sources. The experiments were designed as split plots based on a completely randomized block design with three replications. The main factor was recycled water with three levels (gray water, wastewater from the Kashfroud region of Mashhad, and urban water (control)). The sub-factor included different bacterial strains at four levels, composed of various bacteria combinations, (B1: Psedoumonas flucrecens + Azosporillum liposferum + Thiobacillus thioparus + Aztobactor chorococcum, B2: Paenibacillus polymyxa + Pseudomonas fildensis + Bacillus subtilis + Achromobacter xylosoxidans + Bacillus licheniform, B3: Pseudomonas putida + Acidithiobacillus ferrooxidans + Bacillus velezensis + Bacillus subtilis + Bacillus methylotrophicus + Mcrobacterium testaceum, and the control level without bacterial application (B0). RESULT: The findings revealed significant differences at the 5% probability level across all morphophysiological traits, including plant height, the number and length of lateral branches, growth index, and plant coverage. Moreover, superior morphophysiological traits were observed in plants cultivated in substrates inoculated with wastewater irrigation. Substrates inoculated with bacteria exhibited the highest relative water content (RWC) and chlorophyll levels, coupled with the lowest relative saturation deficit (RSD), electrolyte leakage (EL), and carotenoid levels. Furthermore, plant growth-promoting bacteria (PGPB), from a biochemical perspective, were associated with increased carbohydrates, total protein, and anthocyanin. They also contributed to controlling oxidative stress caused by free radicals by enhancing the activity of antioxidant enzymes, such as guaiacol peroxidase (GPX), polyphenol oxidase (PPO), ascorbate peroxidase (APX), and peroxidase (POD), while reducing catalase enzyme (CAT) activity. This led to increased resistance to stress, as evidenced by a decrease in malondialdehyde and proline levels. The study concludes that the MIX B3, being both ecofriendly and economical, represents an effective strategy for mitigating the adverse effects of wastewater on plants. CONCLUSION: This study showed that plant irrigation using wastewater increases the levels of proline, phenols and oxidative stress. However, the application of plant growth promoting bacteria (PGPB) reduced oxidative damage by increasing antioxidant activity and decreasing proline and phenol levels. These findings show the potential of bacterial treatments to improve plant growth and reduce adverse effects of recycled water irrigation.

Ornamental cabbage (Brassica oleracea var. acephala) responses to phytase enzyme purified from Lactobacillus coryniformis application.

In order to increase the quality and yield of ornamental plants, especially potted ornamental plants, it is necessary to enrich the physical properties of the growing medium and to ensure the continuity of the growing medium. In order to achieve this, organic substances that create a serious cost in ornamental plant cultivation are added to the growing medium. This study was planned to assess the role of inoculation of different levels in the seeds and soaking times of purified phytase, on the plant growth and ornamental plant decorative values in ornamental cabbage plants under nutrient limiting condition in greenhouse. Different doses (E0 : 0 EU, E1 : 5 EU, E2 : 10 EU), soaking times (W15 : 15 min, W30 : 30 min, W60 : 60 min), and their combinations (W15 + E0 , W15 + E1 , W15 + E2 , W30 + E0 , W30 + E1 , W30 + E2 , W60 + E0 , W60 + E1 , W60 + E2 ) of phytase enzyme purified and isolated from the Lactobacillus coryniformis were applied to ornamental cabbage seeds, and they were sown in plug trays filled with appropriate growing medium. Seedlings were planted in plastic pots during their period when the seedlings had four to five true leaves. Treatments of phytase enzyme purified and isolated from the microorganism generally improved the observed parameters. The application of, especially, the highest level of phytase enzyme doses increased the plant height, main stem height, and stem diameter of ornamental cabbage as compared to control (E0 treatment: distilled water). While the highest number of leaves per plant was obtained at E1 and E2 application doses and W30 and W60 soaking times; the highest stem diameter was obtained at E2 application doses and W30 and W60 soaking times. The present study clarified that the purified phytase enzyme can increase ornamental cabbage quality at the appropriate concentration and soaking time and is a promising biotechnology material for agricultural applications, and especially in different ornamental plant species.

First Report of Anthracnose on Giant Philodendron Caused by Colletotrichum siamense in Thailand.

Giant philodendron (Philodendron giganteum Schott) is cultivated in Thailand and has become an important ornamental houseplant with great economic value. During the rainy season in July 2022, anthracnose disease on this plant was observed at a nursery in Saraphi District, Chiang Mai Province (18°40'18" N, 99°03'17" E), Thailand. The area investigated was approximately 800 m². The disease incidence was estimated at above 15% according to the total number of plants (220 plants). The disease severity of each plant was between 25 and 50% of the necrotic lesion on the leaf. Initially, symptoms with brown spots, appeared on leaves, gradually becoming enlarged, elongate, 1 to 11 cm long by 0.3 to 3.5 cm wide, irregular, sunken, dark brown, with a yellow halo surrounding each lesion. Then, the diseased leaves eventually withered and died. Leaf pieces (5 × 5 mm2) of the margins between lesions and the healthy tissue were surface sterilized in 1% NaClO for 1 min, 70% ethanol for 30 s, and rinsed three times with sterile distilled water. Tissues were placed on potato dextrose agar (PDA) and incubated at 25°C in darkness. After three days of incubation, pure fungal colonies were purified by a single hyphal tip method on PDA (Korhonen and Hintikka 1980). Two fungal isolates (SDBR-CMU471 and SDBR-CMU472) with similar morphology were obtained. Fungal colonies on PDA were white and 38 to 40 mm in diameter after 3 days of incubation at 25 °C, then grayish white with cottony mycelia, the reverse side pale yellow after one week of incubation. Both isolates produced asexual structures on PDA. Setae were brown with 1 to 3 septa, 50 to 110 × 2.4 to 4.0 µm, with a cylindrical base, and acuminate tip. Conidiophores were hyaline to pale brown, septate, and branched. Conidiogenous cells were hyaline to pale brown, cylindrical to ampulliform, 9.5 to 35 µm long (n = 50). Conidia were single-celled, straight, hyaline, smooth-walled, cylindrical, ends rounded, guttulate, 9.1 to 19.6 × 3.5 to 5.6 µm (n = 50). Appressoria were brown to dark brown, oval to irregular, smooth-walled, 5 to 10 × 5 to 7.5 µm (n = 50). Morphologically, both fungal isolates resembled members of the Colletotrichum gloeosporioides species complex (Weir et al. 2012; Jayawardena et al. 2021). The internal transcribed spacer (ITS) region of the ribosomal DNA, actin (act), ß-tubulin (tub2), calmodulin (CAL), and glyceraldehyde-3-phosphate dehydrogenase (GAPDH) genes were amplified using primer pairs ITS5/ITS4 (White et al. 1990), ACT-512F/ACT-783R (Carbone and Kohn 1999), T1/T22 (O'Donnell and Cigelnik 1997), CL1C/CL2C (Weir et al. 2012), and GDF1/GDR1 (Templeton et al. 1992), respectively. Sequences were deposited in GenBank (ITS: OQ699280, OQ699281; act: OQ727122, OQ727123; tub2: OQ727124, OQ727125; CAL: OQ727126, OQ727127; GAPDH: OQ727128, OQ727129). Multi-gene (combined data set of ITS, GAPDH, CAL, act, and tub2) maximum likelihood phylogenetic analyses demonstrated that both isolates were identified as C. siamense with 100% support. In a pathogenicity test, leaves of healthy plants were surface sterilized with a 0.1% NaClO solution for 3 min, rinsed three times with sterile distilled water. After being air-dried, a uniform wound (5 pores, 3 mm in width) was made at the equator of each leaf using aseptic needles. Conidial suspensions were collected from two-week-old cultures and suspended in sterile distilled water with 0.05% Tween-20. Fifteen microliters of the conidial suspension (1 × 106 conidia/ml) were placed on wounded attached leaves. As well, wounded control leaves were mock inoculated with sterile distilled water. Ten replications were conducted for each treatment and experiments were repeated twice. The inoculated plants were stored in a greenhouse at conditions of 25 to 30°C and 75 to 85% relative humidity. After 14 days, all the inoculated leaves showed disease symptoms, brown lesions with yellow halos, whereas control leaves remained asymptomatic. The pathogen C. siamense was consistently re-isolated on PDA from the inoculated tissues to complete Koch's postulates. Colletotrichum siamense has been reported as a causal agent on a wide range of host plants in Thailand and throughout the world (Farr and Rossman 2021; Jayawardena et al. 2021). Prior to this study, C. endophytica, C. karsti, C. orchidearum, C. philodendricola, and C. pseudoboninense were identified as causal agents of anthracnose on philodendrons (Xue et al. 2020; Zhang et al. 2023). However, anthracnose caused by Colletotrichum species on giant philodendron (P. giganteum) has not been previously reported. Thus, we propose C. siamense as a new causal agent of anthracnose disease on giant philodendron. This study provides information for further investigation into the epidemiology and management of this disease. Moreover, further investigations should be carried out in other philodendron growing areas of Thailand in order to specifically search for this pathogen.

DNA-Binding One Finger Transcription Factor PhDof28 Regulates Petal Size in Petunia.

Petal size is a key indicator of the ornamental value of plants, such as Petunia hybrida L., which is a popular ornamental species worldwide. Our previous study identified a flower-specific expression pattern of a DNA-binding one finger (Dof)-type transcription factor (TF) PhDof28, in the semi-flowering and full-flowering stages of petunia. In this study, subcellular localization and activation assays showed that PhDof28 was localized in the cell nucleus and could undergo in vitro self-activation. The expression levels of PhDof28 tended to be significantly up-regulated at the top parts of petals during petunia flower opening. Transgenic petunia 'W115' and tobacco plants overexpressing PhDof28 showed similar larger petal phenotypes. The cell sizes at the middle and top parts of transgenic petunia petals were significantly increased, along with higher levels of endogenous indole-3-acetic acid (IAA) hormone. Interestingly, the expression levels of two TFs, PhNAC100 and PhBPEp, which were reported as negative regulators for flower development, were dramatically increased, while the accumulation of jasmonic acid (JA), which induces PhBPEp expression, was also significantly enhanced in the transgenic petals. These results indicated that PhDof28 overexpression could increase petal size by enhancing the synthesis of endogenous IAA in petunias. Moreover, a JA-related feedback regulation mechanism was potentially activated to prevent overgrowth of petals in transgenic plants. This study will not only enhance our knowledge of the Dof TF family, but also provide crucial genetic resources for future improvements of plant ornamental traits.

Responses of the tree peony (Paeonia suffruticosa, Paeoniaceae) cultivar 'Yu Hong' to heat stress revealed by iTRAQ-based quantitative proteomics.

Horticulture productivity has been increasingly restricted by heat stress from growing global warming, making it far below the optimum production capacity. As a popular ornamental cultivar of tree peony, Paeonia suffruticosa 'Yu Hong' has also been suffering from heat stress not suitable for its optimal growth. To better understand the response mechanisms against heat stress of tree peony, investigations of phenotypic changes, physiological responses, and quantitative proteomics were conducted. Phenotypic and physiological changes indicated that 24 h of exposure to heat stress (40 °C) was the critical duration of heat stress in tree peony. The proteomic analyses revealed a total of 100 heat-responsive proteins (HRPs). According to bioinformatic analysis of HRPs, the heat tolerance of tree peony might be related to signal transduction, synthesis/degradation, heat kinetic proteins, antioxidants, photosynthesis, energy conversion, and metabolism. Our research will provide some new insights into the molecular mechanism under the response against the heat stress of tree peony, which will benefit the future breeding of heat-resistant ornamental plants.

First Report of Leaf blight Caused by Stagonosporopsis citrulli on Garden Geranium in China.

Garden geranium (Pelargonium × hortorum L.H. Bailey, Geraniaceae) is a popular ornamental plant cultivated worldwide, whose extracts are used in cosmetics and medicine (Jugulam et al. 2001). On the University of Electronic Science and Technology of China campus (Chengdu, China), leaf blight on the garden geranium was observed during April-September 2021. The average disease incidence was around 40%-50%, which caused severe loss of ornamental value. Initially, circular, brown necrotic areas appear on the margin of the leaves. In the advanced stage of infection, lesions may enlarge rapidly, become irregular in shape, with the central portion of the lesion falling out and defoliation. To isolate the pathogen, symptomatic tissues obtained from diseased leaves were surface-sterilized for 1 min with 0.3% NaClO, rinsed in sterile distilled water, and plated onto potato dextrose agar (PDA). The inoculated plates were incubated for 7 days at 25°C. Successively, pure cultures were obtained by transferring hyphal tips to new PDA plates. A total of 20 isolates were obtained across 25 garden geranium plants investigated. The colonies on the PDA plates reached a diameter of 60-70 mm after 10 days at 25°C, spreading with a regular margin, aerial mycelium white, and black mycelia on the undersides cottony and solitary and globose pycnidia were produced after ten days. Conidia were either cylindrical or short cylindrical, hyaline 4-11 µm × 2-5 µm. These morphologies corresponded to those of Stagonosporopsis species. Sequence data for the 28S nrDNA, the internal transcribed spacer, ß-tubulin, and RNA polymerase II subunit (White et al. 1990, Liu et al. 1999, Aveskamp et al. 2009) were obtained randomly for one of the pure isolates (P1-L4-1-L1-1), which resulted in the GenBank accession numbers ON667723, ON667722, ON677462, and ON677463, respectively. The RAxML analysis (Stamatakis 2014) of the combined sequence data of the isolate P1-L4-1-L1-1 and the reference sequences obtained from GenBank demonstrated that the isolate P1-L4-1-L1-1 formed a strongly support clade with the type isolates (C5-5) of Stagonosporopsis citrulli M.T. Brewer & J.E. Stewart, which has been found on cucurbits (Stewart et al. 2015). The procedure for Koch's postulates was followed to confirm fungal pathogenicity using 4-day-old mycelial disks. A total of 15 same-aged healthy leaves were divided into three groups, and each group received a different treatment. Artificial wounds were created on one group of leaves using a sterile pin, and a 5-mm mycelial plug of the fungus was placed on the injured tissues. Mycelial plugs were also placed on the surfaces of the sets of unwounded leaves. The remaining leaves were maintained as control and inoculated with sterile PDA plugs. The test was repeated three times. Both the wounded and non-wounded leaves exhibited symptoms after 4-9 days identical to those observed in the field. The control group remained asymptomatic, and the morphology of the fungus reisolated from the inoculated leaves was similar to that of S. citrulli. The phylogeny, together with morphological identification and inoculation results, confirmed the identity of the pathogen on garden geranium as S. citrulli. To our knowledge, this is the first report of leaf spot caused by S. citrulli in the garden geranium in the world. Our results may help to provide crucial information for studying the epidemiology and management of this disease.

First Report of Leaf Spot Caused by Colletotrichum fructicola on Magnolia wufengensis in Hubei, China.

Magnolia wufengensis belongs to the Magnoliaceae family. Its variation-rich flowers (tepal number from 9 to 46, tepal color from pink to bright red) and excellent wood characteristics (strong, straight, texture) have important ornamental and economic value (Duan et al. 2019; Luyi et al. 2006). M. wufengensis is popularly cultivated in parks, courtyards, mountains, and along roadsides. In May 2020, leaf spot symptoms were observed on over 85% of M. wufengensis in Yuyangguan Township, Wufeng County, Hubei Province (110.60°E, 30.21°N). The damaged area was over 18.7 hectares. Early symptoms began as small brown spots with a light-yellow halo. Gradual lesions expanded, and the center was withered, gray, and necrotic with a dark brown border. Eventually, several spots combined with larger irregular lesions, turning the leaves yellow and causing them to fall off. The border of lesions and healthy tissues were cut into small pieces (5×5 mm), and surface sterilized with 1% sodium hypochlorite solution for three minutes, rinsed three times with sterile water, and plated on potato dextrose agar (PDA) medium at 25±2 °C with a 12h photoperiod under fluorescent lighting. Pure isolates (MCS1228.1, MCS1228.4, MCS1228.9) were gray to pale grayish, and their average growth rate was 10.5±1.23 mm/day. Conidiophores were hyaline, aseptate, branched. Conidia were hyaline, aseptate, cylindrical, and 14.00 to 25.17 × 4.74 to 6.56 µm in size (average 17.48 × 5.58 µm) (n=50). Appressoria were brown and showed multivariate shape. The morphological characteristics of the isolates corresponded to the description given for Colletotrichum fructicola (Liu et al. 2015). Molecular identification was accomplished through amplification of the internal transcribed spacer (IST), actin (ACT), calmodulin (CAL), chitin synthase (CHS-1) glyceraldehyde-3-phosphate dehydrogenase (GAPDH), and beta-tubulin (TUB2) genes (Fu et al. 2018). The ITS (OL800580.1, OL800581.1, OL800582.1), ACT (GenBank accession No. OL873155- OL873157), CAL (GenBank accession No. OL873158- OL873160), CHS-1 (GenBank accession No. OL873161- OL873163), GAPDH (GenBank accession No. OL873164- OL873166) and TUB2 (GenBank accession No. OL873167- OL873169) sequences were deposited in GenBank. A Bayesian inference phylogenetic tree based on multilocus sequences was constructed, and the sequences of the 3 isolations showed the same homology with C. fructicola (Fu et al. 2018). To fulfill Koch's postulates, 30 potted seedlings were inoculated with 1×10^6 conidia/ml suspension of each isolate by spraying the leaves, and 30 potted seedlings were sprayed with sterile distilled water as control. Inoculated and control plants were kept in a greenhouse with 25/15°C (day/night) temperature and 80% relative humidity. In addition, 30 healthy detached leaves free of pests and diseases were washed three times with sterile distilled water, air-dried, and artificially inoculated using a 6 mm (diameter) PDA medium (5 days incubation) with mycelium. 30 leaves were inoculated with sterile PDA medium as control. All leaves were sprayed with sterile water every 24 hours, covered with plastic wrap, and incubated at 25±2 °C, 100% humidity. The experiment was repeated three times. Similar symptoms to those found initially were both observed on all the inoculated potted seedlings and detached leaves after 14 days and 5 days post inoculation (dpi), respectively. Whereas the controls remained symptomless. The reisolated pathogens from symptomatic tissues were identical to the original isolates. In this study, isolated fungi associated with M. wufengensis leaf spot were identified as C. fructicola based on morphological and multiloci phylogenetic analyses, and Koch's postulates. Colletotrichum species are important plant pathogens and cause diseases in a wide variety of woody and herbaceous plants (Cannon et al. 2012). C. fructicola has been identified as a responsible pathogen for apple (Casanova et al. 2016), Fatsia japonica (Shi et al. 2017), and Rubus corchorifolius (Wu et al. 2021) leaf spot. To our knowledge, this is the first report of C. fructicola causing leaf spot in M. wufengensis in China. This research may contribute to the development of management strategies for this disease.

First report of Fusarium solani (FSSC 6) associated with the root rot of Magnolia denudata in China.

Magnolia denudata (Lilytree or Yulan magnolia) is an important ornamental species of the genus Magnolia. It has considerable economical value because of its beautiful fragrant flowers and excellent tree structure (Wang et al. 2010). In Beijing, nurseries cultivate M. denudata as an ornamental plant and traditional medicine. In May 2020, patches of root rotted plants were observed in a field in Beijing, China, with an estimated incidence of approximately 31%. Early symptoms comprised leaves melanocratic shrunken, and the vascular tissue of roots turned brown. Progressively, the roots rotted and the whole plant died (Fig. 1 a-d). Infected roots tissue was surface disinfested and plated on potato dextrose agar (PDA) medium at 25±2 °C and incubated in the dark for 7 days. Pure cultures were obtained by hyphal tip excision (strain MFR1215.4). Fungal colonies were entire margins, and the aerial mycelium was copious, early white, and gradually developed into cream white. Colonies developed to 45.1 mm in 4 days at 25±2 °C on PDA media. On Spezieller Nährstoffarmer Agar (SNA) medium at 25±2 °C for 10 days. The morphological characteristics including macroconidia, microconidia, and chlamydospores were shown in Fig.1 (i-p). These morphological characteristics of the isolate corresponded to the description given for Fusarium solani sensu lato (Nelson et al. 1983, Summerell, 2003). Molecular identification was confirmed via amplification of translation elongation factor 1α (EF-1α), RNA polymerase I beta subunit gene (RPB1), and RNA polymerase II beta subunit gene (RPB2) regions using EF1/EF2, RPB1-Fa/G2R, RPB2-5f2/7cR, and RPB2-7cF/11aR primers (O'Donnell, 2010). Sequences were registered in GenBank. In the Fusarium-ID database, the EF-1α, RPB1, and RPB2 sequences showed 100% (677/677 bp), 99.8% (1568/1571 bp), and 100% (1457/1457 bp) identity with the F. solani species complex (FSSC). The same species-level identification was also found using Fusarium MLST. A best maximum likelihood tree was constructed using PhyloSuite v1.2.2 (Zhang et al. 2020), and the sequences of the MFR1215.4 isolation showed the same homology with FSSC 6. Pathogenicity tests were conducted on healthy one-year-old M. denudata potted seedlings. 200 ml spore suspension (1×106 spores/ml) was poured over the roots of twenty seedlings, and sterile distilled water was irrigated into twenty seedlings as controls in a greenhouse with 25/15°C day/night temperature and 80% relative humidity. The experiment was repeated three times. All inoculated seedlings showed similar symptoms to those in the field after 65 days, whereas the controls remained symptomless. The reisolating pathogens from symptomatic tissues were identical to the original isolates by morphology and EF-1α sequence identification. Based on morphological, molecular, and pathogenic characterization, the isolated pathogen was identified as FSSC 6. Fusarium species have been recorded in various places of the world and are known to be harmful to numerous plants (Trabelsi et al. 2017). It has been reported that FSSC has infected soybeans (Coleman, 2016, Nelson et al. 1989), oil palm (Hafizi et al. 2013), tobacco (Yang et al. 2020), resulting in sudden death syndrome, crown disease, and root rot. To our knowledge, this is the first report of FSSC-induced root rot in M. denudata in China. This research may contribute to the development of epidemiology and management strategies for root rot caused by FSSC on M. denudata.

Impacts of root pruning intensity and direction on the phytoremediation of moderately Cd-polluted soil by Celosia argentea.

Root pruning can impact the physiological functions of various plants, which influence phytoremediation. A series of root pruning treatments with different combinations of direction (two-side pruning and four-side pruning) and intensity (10, 25, and 33% pruning) were performed on Celosia argentea L. All two-side pruning treatments, regardless of intensity, decreased the dry biomass of the C. argentea roots at the end of the experiment relative to that of the control. However, the two-side-10% and two-side-25% pruning treatments stimulated the growth rate of the plant leaves significantly by 58.6 and 41.4%, respectively, relative to that of the control, and even offset the weight loss of the plant roots. Contrastingly, the two-side-33% pruning treatment reduced the biomass yield of leaves by 24.1%. For the four-side pruning treatments, the low intensity increased the dry weight of both the plant roots and leaves, while both decreased under high-intensity root pruning. The dry weight, Cd content, pigment level, and photosynthetic efficiency in the four-side-10% treatment were higher than those in the other treatments during the experiment. This study indicates that root pruning with a suitable combination of direction and intensity can positively influence the Cd removal ability of C. argentea.

Our study suggests that a suitable root pruning pattern can significantly increase the phytoremediation effect of Celosia argentea L. Compared with chemical and biological regulation including plant hormone application, chemical reagent spraying, and endophytes inoculation which might introduce unpredictable risks into the ecological system, root pruning can be considered as an environmentally friendly physical trigger to modulate physiological features and to induce advantages in plants. This finding can be extrapolated into the real-world easily since root pruning is an established, convenient, and feasible method. We believe readers would be interested in this method.

Allopatric Lineage Divergence of the East Asian Endemic Herb Conandron ramondioides Inferred from Low-Copy Nuclear and Plastid Markers.

The evolutionary histories of ornamental plants have been receiving only limited attention. We examined the origin and divergence processes of an East Asian endemic ornamental plant, Conandron ramondioides. C. ramondioides is an understory herb occurring in primary forests, which has been grouped into two varieties. We reconstructed the evolutionary and population demography history of C. ramondioides to infer its divergence process. Nuclear and chloroplast DNA sequences were obtained from 21 Conandron populations on both sides of the East China Sea (ECS) to explore its genetic diversity, structure, and population differentiation. Interestingly, the reconstructed phylogeny indicated that the populations should be classified into three clades corresponding to geographical regions: the Japan (Honshu+Shikoku) clade, the Taiwan-Iriomote clade, and the Southeast China clade. Lineage divergence between the Japan clade and the Taiwan-Iriomote and Southeast China clades occured 1.14 MYA (95% HPD: 0.82-3.86), followed by divergence between the Taiwan-Iriomote and Southeast China clades approximately 0.75 MYA (95% HPD: 0.45-1.3). Furthermore, corolla traits (floral lobe length to tube length ratios) correlated with geographical distributions. Moreover, restricted gene flow was detected among clades. Lastly, the lack of potential dispersal routes across an exposed ECS seafloor during the last glacial maximum suggests that migration among the Conandron clades was unlikely. In summary, the extant Conandron exhibits a disjunct distribution pattern as a result of vicariance rather than long-distance dispersal. We propose that allopatric divergence has occurred in C. ramondioides since the Pleistocene. Our findings highlight the critical influence of species' biological characteristics on shaping lineage diversification of East Asian relic herb species during climate oscillations since the Quaternary.

First Report of Powdery Mildew Caused by Golovinomyces ambrosiae on Verbena bonariensis in Korea.

Verbena bonariensis L., named as purple-top vervain or Argentinian vervain, is native to tropical South America. It is cultivated worldwide as an ornamental plant. During summer and autumn of 2020, over 50% of the leaves of V. bonariensis were found infected with powdery mildew in a flower garden in Seoul (37°35'19"N 127°01'07"E), Korea. White, superficial mycelia developed initially on the leaves and subsequently covered surfaces of leaves and stems, are resulting in leaf discoloration, early defoliation, and shoots distortion. Heavily infected plants lost ornamental value. A representative voucher specimen was deposited in the Korea University herbarium (KUS-F32168). Morphological characterization and measurements of conidiophores and conidia were carried out using fresh samples. Microscopic observation showed that aAppressoria on the superficial hypha were nipple-shaped, but rarely found or nearly absent. Conidiophores (n = 30) were cylindrical, 110 to 220 × 10 to 12 µm, and produced 2 to 5 immature conidia in chains with a sinuate outline, followed by 2 to 3 short cells. Foot-cells of conidiophores were straight, cylindrical, and 46 to 90 µm long. Conidia (n = 30) were hyaline, ellipsoid to doliiform, 28 to 40 × 18 to 24 µm with a length/width ratio of 1.3 to 2.0, and contained small be like oil-like drops, but without distinct fibrosin bodies. Primary conidia were apically rounded and sub-truncate at the base. Germ tubes were produced at perihilar position of the conidia. Chasmothecia were not observed. These morphological characteristics were typical of the conidial stage of the genus Golovinomyces (Braun and Cook 2012, Qiu et al. 2020). To identify the fungus, rDNA was extracted from the voucher sample. PCR products were amplified using the primer pair ITS1F/PM6 for internal transcribed spacer (ITS), and PM3/TW14 for the large subunit (LSU) of the rDNA (Takamatsu and Kano 2001). The resulting sequences were registered to GenBank (MW599742 for ITS, and MW599743 for LSU). Using Blast'n search of GenBank, sequences showed 100% identity for ITS and LSU with G. ambrosiae (MT355557, KX987303, MH078047 for ITS, and AB769427, AB769426 for LSU), respectively. Thus, based on morphology and molecular analysis, the isolate on V. bonariensis in Korea was identified as G. ambrosiae (Schwein.) U. Braun & R.T.A. Cook. Pathogenicity tests were carried out by touching an infected leaf onto healthy leaves of disease-free pot-grown plants using a replication of five plants, with five non-inoculated plants used as controls. After 7 days, typical powdery mildew colonies started to appear on the inoculated leaves. The fungus on inoculated leaves was morphologically identical to that originally observed in the field. All non-inoculated control leaves remained symptomless. On different global Verbena species, tThere have been many reports of Golovinomyces powdery mildews including G. cichoracearum s.lat., G. longipes, G. monardae, G. orontii s.lat., and G. verbenae (Farr and Rossman 2021). In China, G. verbenae was recorded on V.erbena phlogiflora (Liu et al. 2006). Golovinomyces powdery mildew has not been reported on Verbena spp. in Korea. Powdery mildew has been reported on V. bonariensis in California, but identity of the causal agent had not been reported. To our knowledge, this is the first report on the identity of the powdery mildew caused by G. ambrosiae on V. bonariensis in Korea. Since heavily infected plants lost ornamental value, appropriate control measures should be developed.

Promotion of Zinc Tolerance, Acquisition and Translocation of Phosphorus in Mimosa pudica L. Mediated by Arbuscular Mycorrhizal Fungi.

Heavy metal contamination of soil is of increasing concern because of its potential risk to human health. In this study, two AMFs (Rhizophagus intraradices and Funneliformis mosseae) substantially increased the biomass of bashfulgrass in Zn-contaminated soil, even at Zn levels of up to 600 mg kg-1. Zn uptake in R. intraradices- and F. mosseae-mycorrhizal bashfulgrass was increased by 40-fold and 7-fold, respectively, when plants grown in Zn-contaminated (400 mg kg-1) soil. Elemental analysis showed that neither AMF had an effect on Zn concentration in plant tissues, including the roots and shoots. However, a significant increase of phosphorus (P) concentration was observed, suggesting the increased is from the improved use efficiency of soil nutrients by AMFs. Comparing the two AMFs, better growth performance with more biomass occurred with R. intraradices-inoculated bashfulgrass in Zn-contaminated soil. This is consistent with R. intraradices being more tolerant to Zn than F. mosseae, indicated by a higher colonization percentage in bashfulgrass roots. Taken together, our data indicate that AMFs possibly improve acquisition and translocation of P to promote increased biomass. Moreover, mycorrhiza did not enhance Zn accumulation in shoots and roots of bashfulgrass at the same Zn level. In the future, developing AMF (especially R. intraradices) inoculation of plants might be a desirable means of safe production of ornamental plants in metal-polluted soil.

Lead Tolerance and Enrichment Characteristics of Several Ornamentals Under Hydroponic Culture.

The growth response, tolerance, and enrichment characteristics of six ornamental species, Chlorophytum comosum, Calendula officinalis, Iris lacteal, Belamcanda chinensis, Saponaria officinalis, and Polygonum lapathifolium were studied under hydroponic culture with lead (Pb) concentrations ranging from 0 to 1000 mg/L. The results showed that the growth of the tested ornamental species under Pb stress was inhibited. Belamcanda chinensis presented the largest tolerance index (0.75), and Calendula officinalis had the highest toxicity threshold (500 mg/L) under Pb stress. The highest Pb contents in the shoots were detected in Iris lacteal and Belamcanda chinensis. The enrichment coefficients in the shoots of Iris lacteal and Belamcanda chinensis were significantly higher than those in the other ornamental species. In conclusion, Iris lacteal and Belamcanda chinensis are the most tolerant and have the greatest Pb enrichment and translocation abilities under Pb stress, and thus, they have a strong potential to restore Pb-contaminated water bodies and soils.

Variability in morphological traits of seedlings from five Euonymus japonicus cultivars.

In this study, we investigated the variability in morphological traits of seedlings from five Euonymus japonicus cultivars. We measured seedling heights, root collar diameters, leaf lengths and widths, root lengths, root numbers, and twig numbers of 60 seedlings from each cultivar. The E. japonicus cultivars Variegate and Green Rocket had the highest (95.8%) and lowest (70.3%) rooting percentages, respectively. With the exception of root lengths (p > 0.05), all morphological characteristics significantly differed among all cultivars (p < 0.05). In particular, the cultivar Green Rocket performed better than all other cultivars, with greater seedling heights and root collar diameters. These data warrant further studies for quantifying differences in traits among these cultivars.

Rapid visual detection of lily mottle virus using a loop-mediated isothermal amplification method.

Lily mottle virus (LMoV; genus Potyvirus, family Potyviridae) infects plants of the genus Lilium, causing a reduction in flower and bulb quality. A rapid and sensitive loop-mediated isothermal amplification (LAMP) assay was developed to detect the coat protein gene of LMoV. This LAMP method was highly specific for LMoV, with no cross-reaction with other lily viruses. The sensitivity of LMoV using the LAMP assay was 100 times more sensitive than that using conventional polymerase chain reaction. A reverse transcription LAMP (RT-LAMP) was then successfully applied to detect LMoV RNA. The newly established LAMP and one-step RT-LAMP provide an alternative method for detecting LMoV in lily plants.

Screening ornamental plants to identify potential Cd hyperaccumulators for bioremediation.

To identify possible cadmium (Cd) accumulators or hyperaccumulators among ornamental plants, a pot experiment involving increasing Cd concentration (0, 5, 15, 30, 60, and 100 mg kg-1) was conducted among seven species. The principal objective was to screen for ornamental plants with an exceptional ability to accumulate and translocate Cd ions as well as sufficient biomass for harvesting. Regarding shoot biomass, root biomass, plant height and tolerance index (TI), Malva rotundifolia showed high tolerance to Cd and Malva crispa, Sida rhombifolia, Celosia argentea and Celosia cristata medium tolerance; Althaea rosea and Abutilon theophrasti were more sensitive to Cd than the other plants. A hormetic response was induced by Cd in M. crispa, C. argentea, C. cristata and M. rotundifolia. Based on its capacity for Cd accumulation, bioaccumulation coefficients (BCFs) and translocation factors (TFs), M. rotundifolia was selected from candidate plants after 60 days of exposure to Cd-contaminated soil and found to have accumulated more than 200 mg kg-1 Cd in its roots and 900 mg kg-1 in its shoots. Moreover, M. rotundifolia BCFs and TFs were higher than 1.0, with the former ranging from 1.41 to 3.31 and the latter from 1.03 to 7.37. Taken together, these results indicate that M. rotundifolia can be classified as a model hyperaccumulator.

Recent advances in the research and development of blue flowers.

Flower color is the most important trait in the breeding of ornamental plants. In the floriculture industry, however, bluish colored flowers of desirable plants have proved difficult to breed. Many ornamental plants with a high production volume, such as rose and chrysanthemum, lack the key genes for producing the blue delphinidin pigment or do not have an intracellular environment suitable for developing blue color. Recently, it has become possible to incorporate a blue flower color trait through progress in molecular biological analysis of pigment biosynthesis genes and genetic engineering. For example, introduction of the F3'5'H gene encoding flavonoid 3',5'-hydroxylase can produce delphinidin in various flowers such as roses and carnations, turning the flower color purple or violet. Furthermore, the world's first blue chrysanthemum was recently produced by introducing the A3'5'GT gene encoding anthocyanin 3',5'-O-glucosyltransferase, in addition to F3'5'H, into the host plant. The B-ring glucosylated delphinidin-based anthocyanin that is synthesized by the two transgenes develops blue coloration by co-pigmentation with colorless flavone glycosides naturally present in the ray floret of chrysanthemum. This review focuses on the biotechnological efforts to develop blue flowers, and describes future prospects for blue flower breeding and commercialization.

Response to cadmium and phytostabilization potential of Platycladus orientalis in contaminated soil.

The tolerance characteristics and phytostabilization potential of Platycladus orientalis grown in soil contaminated by cadmium (Cd) were studied using a greenhouse experiment. The results showed that the ornamental plant P. orientalis had high tolerance for Cd in contaminated soil at 24.6 mg·kg-1 and its physiological activities were slightly affected after 203 days (d) of cultivation. Moreover, Cd in soil at 9.6 mg·kg-1 was beneficial for P. orientalis growth, and the total biomass after 203 d cultivation was significantly (p < 0.05) increased by 35.03%, while the contents of chlorophyl a, chlorophyl b and carotenoid in leaves also increased by 20.84%, 44.06% and 28.25% compared to the control, respectively. Meanwhile, the Cd content in the tissues of P. orientalis was increased with both plant growth and the Cd content in the soil. The uptake of Cd in P. orientalis roots was greater than in shoots, with the Cd content in roots reaching 41.45 mg·kg-1. P. orientalis, an ornamental plant, that accumulates Cd predominantly in its roots, can be suggested as a promising plant for phytostabilization in Cd-contaminated soil.

Phytostabilization potential of ornamental plants grown in soil contaminated with cadmium.

In a greenhouse experiment, five ornamental plants, Osmanthus fragrans (OF), Ligustrum vicaryi L. (LV), Cinnamomum camphora (CC), Loropetalum chinense var. rubrum (LC), and Euonymus japonicas cv. Aureo-mar (EJ), were studied for the ability to phytostabilization for Cd-contaminated soil. The results showed that these five ornamental plants can grow normally when the soil Cd content is less than 24.6 mg·kg-1. Cd was mainly deposited in the roots of OF, LV, LC and EJ which have grown in Cd-contaminated soils, and the maximum Cd contents reached 15.76, 19.09, 20.59 and 32.91 mg·kg-1, respectively. For CC, Cd was mainly distributed in the shoots and the maximum Cd content in stems and leaves were 12.5 and 10.71 mg·kg-1, however, the total amount of Cd in stems and leaves was similar with the other ornamental plants. The enzymatic activities in Cd-contaminated soil were benefited from the five tested ornamental plants remediation. Soil urease and sucrase activities were improved, while dehydrogenase activity was depressed. Meanwhile, the soil microbial community was slightly influenced when soil Cd content is less than 24.6 mg·kg-1 under five ornamental plants remediation. The results further suggested that ornamental plants could be promising candidates for phytostabilization of Cd-contaminated soil.