First Report of Post-Harvest Anthracnose of Kiwifruit Caused by Colleotrichum fioriniae in Liaoning and Sichuan Province, China.

Kiwifruit (Actinidia spp.) is one of the most important fruit crops in China. Post-harvest anthracnose symptoms were observed on kiwifruit in October 2021. Kiwifruits 'Longcheng 2' (n=200) were obtained from an orchard in Kuandian city of Liaoning province, China (124°32'E, 40°20'N). And cultivar 'Cuiyu' (n=100) were harvested from orchards in Mianzhu city, Sichuan Province, China (104°03'E, 31°15'N). After storage at 24 °C and 80% relative humidity (RH) for 8 days, the disease incidence of 'Longcheng 2' and 'Cuiyu' was 30% and 15%, respectively. Symptoms of diseased fruits appeared as water-soaked, irregular and light brown lesions. Orangish conidial masses were observed on some fruits. Ten lesion margins (5×5 mm) from 'Longcheng2' or 'Cuiyu' were respectively excised, surface sterilized by 70% ethanol (1 min), 1% NaOCl (5 min), washed, dried, plated on potato dextrose agar (PDA), and incubated at 25 °C for 5 days. Eight isolates were obtained from 'Longcheng 2' (LC1-3 to LC1-10) and nine strains from 'Cuiyu' (CY1-2 to CY1-10). The representative isolates LC1-3 and CY1-2 were put on PDA, and appeared white to pale gray on the upper side. However, isolate LC1-3 secreted red pigments after 7 days of culture. Conidia of LC1-3 were hyaline, smooth-walled, single-celled, cylindrical (3.0 to 4.9×7.2 to 14.7 µm, n=50). Ellipsoidal single cell conidia of CY1-2 were hyaline, and ranged in size from 3.2 to 5.0×8.5 to 13.9 µm (n=50) born on conidiophores. Appressorium of isolates LC1-3 and CY1-2 were globose to ellipsoid with 4.2 to 7.4×7.3 to 10.8 µm and 3.0 to 4.9×6.3 to 10.3 µm in size, respectively (n=50) (Fu et al. 2019 ). Four genes (ACT, CHS, GAPDH, TUB2) and the ITS region were successfully amplified and sequenced from all isolates (Weir et al. 2012). Based on sequence alignment, the isolates from 'Longcheng 2' or 'Cuiyu' were identical. BLAST analysis of the ACT, CHS, GAPDH, ITS and TUB2 sequences of LC1-3 (ON018724, ON018722, ON018720, OM980324, ON018718) or CY1-2 (ON018725, ON018723, ON018721, OM980325, ON018719) showed high similarity with C. fioriniae (CBS 128517; JQ949613, JQ948953, JQ948622, MH865005, JQ949943) were 97.1% to 99.7% or 98.1% to 99.7%, respectively. Phylogenetic analysis using concatenated sequences (maximum likelihood method) with MEGA 11 showed LC1-3 and CY1-2 were located within the same clade with C. fioriniae. Previous studies showed that C. fioriniae was classified into three subclades (Damm et al. 2012; Fu et al. 2019). However, LC1-3 and CY1-2 were located within a new subclade, namely the subclade IV. To test pathogenicity, healthy and mature kiwifruits 'Donghong', 'Cuiyu', 'Xuxiang', 'Hayward' and 'Jinyan' were surface sterilized. Each un-wounded fruit was dropped with 10 µl conidial suspension (105 conidia/ml) on the fruit surface. All fruits were placed into a plastic box and stored at 24 °C under 80% RH. Each treatment consisted of 10 fruits and were repeated three times. After 8 days, typical anthracnose lesions were observed on all inoculated fruits. Whereas, the controls treated with sterile distilled water remained asymptomatic. The pathogens re-isolated from diseased fruits were similar morphological and identical to the original isolates, fulfilling Koch's postulates. Anthracnose caused by C. fioriniae has been reported on many fruits (Ling et al. 2020; Waller et al. 2021), but to our knowledge, this is the first report of anthracnose on kiwifruit caused by C. fioriniae. The results will provide valuable information for avoiding post-harvest anthracnose on kiwifruit.

First Report of root rot Caused by Fusarium solani and F. breve on kiwifruit in China.

China is considered as the main producer of kiwifruit (Actinidia spp.) in the world. During 2020-2021, root rot (~8000 plants, ~5% disease incidence) of 3-year-old kiwifruit (cv. Xuxiang) was observed in Lujiang County (117°24'E, 31°15'N), Anhui, China. This disease usually occurred in fields with poor drainage in hot and humid summers. Symptoms started on leaves showing dehydration and curling, the last root of diseased plant turned black and died. Dig out the skin on rotten root was cracking and flaking and white mycelium covered on surface. Twenty rotten tissues from ten plants were cut and surface disinfected with 1% NaOCl for 5 min, rinsed in sterile water, and cultured on potato dextrose agar (PDA) at 25 ± 2°C in the dark. Fifteen fungal isolates were obtained. The first type (KWRR1, 3-10) was cotton-like, reverse with white outer margin, and light brown inner region on PDA. The second type (KWRR2, 11-15) was cotton-like on PDA but appeared pale yellow in reverse. On oatmeal agar, the KWRR1 colony was flat with little aerial hyphae and was red, while KWRR2 was hyaline. On carnation leaf agar (CLA), microconidia of the KWRR1 and KWRR2 isolates were reniform, fusiform or oblong, 0-1 septate, and measuring 1.9-4.3×8.4-15.7 µm and 3.0-3.8×8.2-16.7 µm, respectively (n=50). The macroconidia of KWRR1 were straight or moderately curved, 3-5 septa (2.7-4.6×21.5-52.6 µm in size, n=50). For KWRR2, the macroconidia were straight or slightly curved and with 3-4 septate, 4.1-4.8×26.1-30.8 µm (n=50). Chlamydospores of the KWRR1 and KWRR2 isolates were 1-2 celled, irregular globose, measuring 4.5-8.5 µm and 7.6-9.0 µm diam, respectively (n=50). To identify the isolates, four DNA fragments (RPB1, RPB2, ITS and TEF-1α) were amplified and sequenced from all isolates (O'Donnell, et al. 2012; White et al. 1990; O'Donnell et al. 2022). BLAST analysis of the RPB1, RPB2, ITS and TEF-1α sequences of the KWRR1 isolates (OL474057, OL474055, OL468550, OP382187) showed highest identity with F. solani (NRRL66304; MW218134, KT313623, KT313633, KT313611) at 98.2%-99.8%, while KWRR2 (OL505579, OL474056, OL468551, OP382188) showed that their homology with F. breve (NRRL28009; HM347149, EF470136, DQ094351, DQ246869) at 98.2%-99.4%. F. solani and F. breve belong to clade 3 of the F. solani species complex (FSSC) (Geiser et al. 2021). Phylogenetic analysis based on RPB2, ITS and TEF-1α sequences with MEGA7 software (Sisic et al. 2018), placed the KWRR1 sequences with F. solani (FSSC5), while there of KWRR2 nested with F. breve (FSSC15). One-year-old seedlings (n=6) of 'Xu Xiang', growing in a greenhouse (at 28℃, relative humidity 80%), were inoculated by drenching the soil with a conidial suspension with one of the two isolates (30 ml, 106 conidia/ml). Control plants (n=6) were inoculated with sterilized water and the pathogenicity assay was repeated three times. One month post-inoculation, the leaves of inoculated plants became chlorotic, wilted and died, whereas the controls were disease-free. F. solani and F. breve were successfully reisolated from diseased samples (n=6) and verified based on morphology and sequencing as described above, fulfilling Koch's postulates. Members of the FSSC cause root rot on many hosts (Coleman. 2016; Schroers et al. 2016), but this is the first report of F. solani and F. breve causing root rot disease on kiwifruit in China. The result will serve as the foundation for management of root rot of kiwifruit.

High-Quality Genome Resource of the Pathogen of Diaporthe (Phomopsis) phragmitis Causing Kiwifruit Soft Rot.

Diaporthe spp. are critical plant pathogens that cause wood cankers, wilt, dieback, and fruit rot in a wide variety of economic plant hosts and are regarded as one of the most acute threats faced by the kiwifruit industry worldwide. Diaporthe phragmitis NJD1 is a highly pathogenic isolate of soft rot of kiwifruit. Here, we present a high-quality genome-wide sequence of D. phragmitis NJD1 that was assembled into 28 contigs containing a total size of 58.33 Mb and N50 length of 3.55 Mb. These results lay a solid foundation for understanding host-pathogen interaction and improving disease management strategies.[Formula: see text] Copyright © 2021 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

First Report of Root Rot on kiwifruits Caused by Athelia rolfsii in Hefei, China.

Kiwifruits (Actinidia ssp.), known as "King of vitamin C", have been wildly cultivated. In August 2020, about 15% of A. deliciosa (cv. Xuxiang) and A. macrosperma (rootstock) plants displayed symptoms typical of root rot at a farm in Hefei (117°25'E, 31°86'N), Anhui Province of China (Fig.1 a-b). Symptoms first appeared at the root and stem junction which were covered by cottony white mycelium during warm and humid summer. Then, the infected tissues were rotted, and subsequently the whole plant withered. Tan to brown sclerotia were observed on the basal stem epidermis and soil surface surrounding the stem (Fig.1 c-d). Infected plant tissues and sclerotia were collected for isolating the fungal pathogen. The samples were surface sterilized in 70% alcohol for 30 s, followed by 2% sodium hypochlorite for 3 min, washed five times with sterile double-distilled water (ddH2O), dried, placed on potato dextrose agar, and incubated at 25 °C in the dark. In total, twelve fungal isolates were obtained. The mycelia of all the isolates were white with a fluffy appearance (Fig.1 e). Sclerotia formed after 7 days were initially white (Fig.1 f) and gradually turned to dark brown (Fig.1 g) measuring 0.67 to 2.03 mm in diameter (mean = 1.367 ± 0.16 mm; n = 30). Hyphae were hyaline, septate. Some cells possessed multiple nuclei (Fig.1 h) and clamp connections (Fig.1 i). No spores were observed. For species-level identification, ITS1/ITS4 and EF1-983F/EF1-2218R primers were used to amplify the internal transcribed spacer regions (ITS) and translation elongation factor-1 alpha regions (TEF-1α), respectively (White et al. 1990; Rehner & Buckley 2005). Based on ITS and TEF-1α sequence analyses, all 12 isolates were categorized into two groups, group one including isolates NC-1 and NC-6~10 and group two containing NC-2~5 and NC-11~12. The length of ITS sequences for NC-1 (MW311079) was 684bp and 99% to 100% similar to Athelia rolfsii (MN610007.1, MN258360.1). Similarly, ITS sequences for NC-2 (MW311080) were 99% to 100% similar to A. rolfsii (MH858139.1; MN872304.1). Also, TEF-1α sequences of NC-1 (MW322687) and NC-2 (MW322688) were 96% to 99% similar to sequences of A. rolfsii (MN702794.1, GU187681.1, MN702789.1). Based on morphology and phylogenetic analyses (Fig.1 j&k), the isolates NC-1 and NC-2 were identified as Athelia rolfsii (anamorph Sclerotium rolfsii) (Mordue. 1974; Punja. 1985). To fulfill Koch's postulates, ten sclerotia of NC-1 were incorporated into the soil near stems of healthy Xuxiang plants (Fig.2 a). Similar treatments were also used for plants of A. macrosperma or A. arguta (Fig.2 g&m). Each control group had the same number of plants (n=3) for inoculating with ddH2O. The plants were kept in an incubator with a relative humidity of 80% and temperature of 28°C with 16/8 hours light/dark photoperiod. After twenty days, the pathogen-inoculated plants developed similar symptoms of root rot observed in the field (Fig.2 b-d, h-j, n-o). Similarly, four days after inoculation with sclerotia, leaves developed water-soaked lesions (Fig.2 e, k&p). No significant difference in pathogenicity was observed between NC-1 and NC-2. Non-inoculated control plants remained disease-free (Fig.2 f, l&q). The pathogenicity experiments were repeated three times. The pathogen was re-isolated from infected tissues and sclerotia, and isolates were confirmed as A. rolfsii by the ITS sequences. A. rolfsii has been reported to cause root rot in kiwifruit in the USA (Raabe. 1988). To our knowledge, this is the first report A. rolfsii causing root rot on kiwifruits in China.

Investigation of the role of AcTPR2 in kiwifruit and its response to Botrytis cinerea infection.

BACKGROUND: Elucidation of the regulatory mechanism of kiwifruit response to gray mold disease caused by Botrytis cinerea can provide the basis for its molecular breeding to impart resistance against this disease. In this study, 'Hongyang' kiwifruit served as the experimental material; the TOPLESS/TOPLESS-RELATED (TPL/TPR) co-repressor gene AcTPR2 was cloned into a pTRV2 vector (AcTPR2-TRV) and the virus-induced gene silencing technique was used to establish the functions of the AcTPR2 gene in kiwifruit resistance to Botrytis cinerea. RESULTS: Virus-induced silencing of AcTPR2 enhanced the susceptibility of kiwifruit to Botrytis cinerea. Defensive enzymes such as superoxide dismutase (SOD), peroxidase (POD), catalase (CAT), and phenylalanine ammonia-lyase (PAL) and endogenous phytohormones such as indole acetic acid (IAA), gibberellin (GA3), abscisic acid (ABA), and salicylic acid (SA) were detected. Kiwifruit activated these enzymes and endogenous phytohormones in response to pathogen-induced stress and injury. The expression levels of the IAA signaling genes-AcNIT, AcARF1, and AcARF2-were higher in the AcTPR2-TRV treatment group than in the control. The IAA levels were higher and the rot phenotype was more severe in AcTPR2-TRV kiwifruits than that in the control. These results suggested that AcTPR2 downregulation promotes expression of IAA and IAA signaling genes and accelerates postharvest kiwifruit senescence. Further, Botrytis cinerea dramatically upregulated AcTPR2, indicating that AcTPR2 augments kiwifruit defense against pathogens by downregulating the IAA and IAA signaling genes. CONCLUSIONS: The results of the present study could help clarify the regulatory mechanisms of disease resistance in kiwifruit and furnish genetic resources for molecular breeding of kiwifruit disease resistance.

[Effect of abscisic acid on physiological characteristics in Lonicera macranthoides seedlings under salt stress].

OBJECTIVE: To improve salt resistance of Lonicera macranthoides seedlings and provide reference for its cultivation of salt tolerance. METHODS: Pretreatment of seedlings with abscisic acid (ABA) of different concentrations were used to study the effect of ABA on their physiological and biochemical characteristics under 200 mmol/L NaCl for 7 days. RESULTS: Exogenous ABA significantly decreased the content of malondialdehyde (MDA), increased the contents of chlorophyll, soluble sugar, soluble protein and activities of protected enzymes such as peroxidase (POD), catalase (CAT) and superoxide dismutase (SOD). CONCLUSION: It is proposed that exogenous ABA as chemical activator can induce salt resistance and decrease alleviate damage degree of salt stress of Lonicera macranthoides seedlings in a dose-dependent manner.

The complete chloroplast genome sequence of Actinidia chinensis Planch. 'Hongyang', a typical red core pulp in China.

Actinidia chinensis Planch. 'Hongyang' Wu and Li 1993, also known as red-fleshed kiwifruit, has a high vitamin C content and with high economic and nutritional value. Here, we assembled the complete chloroplast genome of A. chinensis Planch. 'Hongyang', which was 156,267 bp in length, contained a large single-copy region (LSC) of 87,866 bp, a small single-copy region (SSC) of 20,335 bp, and two inverted repeat (IR) regions of 24,033 bp. In addition, the chloroplast genome contained 132 genes, including 85 protein-coding, 39 tRNA, and eight rRNA genes. Overall GC content in the genome was 37.2%, with the corresponding values in the LSC, SSC, and IR regions of 35.5%, 31.1%, and 42.9%, respectively. Phylogenetic analysis indicated that A. chinensis Planch. 'Hongyang' was clustered with that of A. callosa var. strigillosa, A. deliciosa, A. melanandra, A. chinensis and A. setosa in the same branch.

The role of AcPGIP in the kiwifruit (Actinidia chinensis) response to Botrytis cinerea.

Kiwifruit (Actinidia chinensis) is rich in nutritional and medicinal value. However, the organism responsible for grey mould, Botrytis cinerea, causes great economic losses and food safety problems to the kiwifruit industry. Understanding the molecular mechanism underlying postharvest kiwifruit responses to B. cinerea is important for preventing grey mould decay and enhancing resistance breeding. Kiwifruit cv. 'Hongyang' was used as experimental material. The AcPGIP gene was cloned and virus-induced gene silencing (VIGS) was used to explore the function of the polygalacturonase inhibiting protein (PGIP) gene in kiwifruit resistance to B. cinerea. Virus-induced silencing of AcPGIP resulted in enhanced susceptibility of kiwifruit to B. cinerea. Antioxidant enzymes, secondary metabolites and endogenous hormones were analysed to investigate kiwifruit responses to B. cinerea infection. Kiwifruit effectively activated antioxidant enzymes and secondary metabolite production in response to B. cinerea, which significantly increased Indole-3-acetic acid (IAA), gibberellin 3 (GA3) and abscisic acid (ABA) content relative to those in uninfected fruit. Silencing of AcPGIP enabled kiwifruit to quickly activate hormone-signaling pathways through an alternative mechanism to trigger defence responses against B. cinerea infection. These results expand our understanding of the regulatory mechanism for disease resistance in kiwifruit; further, they provide gene-resource reserves for molecular breeding of kiwifruit for disease resistance.

A Comparative Analysis of the Microbiome of Kiwifruit at Harvest Under Open-Field and Rain-Shelter Cultivation Systems.

The composition of microbial communities can directly affect fruit quality, health status, and storability. The present study characterized the epiphytes and endophytes of "Hongyang" and "Cuiyu" kiwifruit at harvest under grown under open-field (OF) and rain-shelter (RS) cultivation systems. Disease incidence in kiwifruit was significantly lower (p < 0.05) under the RS system than it was under the OF system. High-throughput sequencing [16S V3-V4 ribosomal region and the fungal internal transcribed spacer (ITS2)] was conducted to compare the composition of the epiphytic and endophytic microbial community of kiwifruit under the two cultivation systems. Results indicated that the abundance of Actinobacteria, Bacteroidetes, Enterobacteriales, Acetobacterales, Sphingomonas, Pseudomonas, and Sphingobacterium was higher under the RS system, relative to the OF system, while the abundance of Capnodiales, Hypocreales, Vishniacozyma, and Plectosphaerella was also higher under the RS system. Some of these bacterial and fungal taxa have been reported to as act as biocontrol agents and reduce disease incidence. Notably, the α-diversity of the epiphytic bacterial and fungal communities on kiwifruit was higher under RS cultivation. In summary, RS cultivation reduced natural disease incidence in kiwifruit, which may be partially attributed to differences in the structure and composition of the microbial community present in and on kiwifruit.

Whole Genome Sequence of Alternaria alternata, the Causal Agent of Black Spot of Kiwifruit.

Alternaria alternata is a pathogen in a wide range of agriculture crops and causes significant economic losses. A strain of A. alternata (Y784-BC03) was isolated and identified from "Hongyang" kiwifruit and demonstrated to cause black spot infections on fruits. The genome sequence of Y784-BC03 was obtained using Nanopore MinION technology. The assembled genome is composed of 33,869,130bp (32.30Mb) comprising 10 chromosomes and 11,954 genes. A total of 2,180 virulence factors were predicted to be present in the obtained genome sequence. The virulence factors comprised genes encoding secondary metabolites, including non-host-specific toxins, cell wall-degrading enzymes, and major transcriptional regulators. The predicted gene clusters encoding genes for the biosynthesis and export of secondary metabolites in the genome of Y784-BC03 were associated with non-host-specific toxins, including cercosporin, dothistromin, and versicolorin B. Major transcriptional regulators of different mycotoxin biosynthesis pathways were identified, including the transcriptional regulators, polyketide synthase, P450 monooxygenase, and major facilitator superfamily transporters.

Transcriptome sequencing and endogenous phytohormone analysis reveal new insights in CPPU controlling fruit development in kiwifruit (Actinidia chinensis).

Kiwifruit (Actinidia chinensis) is a rich nutritious fruit crop owing to a markedly higher content of vitamin C and minerals. To promote fruit set and to increase the yield of kiwifruit, forchlorfenuron (CPPU) has been widely applied. However, the molecular details regarding CPPU controlling kiwifruit development, especially at the fastest fruit growth stage, remain unknown. In the present study, we measured the effect of CPPU on developmental regulation in red-fleshed kiwifruit (Actinidia chinensis 'Hongyang'). Additionally, a cytological analysis was performed to clarify the precise changes in the cell structure of the CPPU-treated kiwifruits. Moreover, the concentration of endogenous phytohormones, including indoleacetic acid (IAA), zeatin (ZT), gibberellic acid 3 (GA3), and abscisic acid (ABA), were measured by Enzyme-linked Immunosorbent Assay (ELISA). Furthermore, RNA-Seq was performed to dissect the complicated molecular mechanisms, with a focus on biosynthesis, metabolism, and signaling compounds, such as endogenous hormones, sugars, and L-ascorbic acid. Our results demonstrated that CPPU treatment not only regulates the size and weight of a single fruit but also improves the quality in 'Hongyang' kiwifruit through the accumulation of both soluble sugar and vitamin C. It was also seen that CPPU regulates kiwifruit development by enhancing cell expansion of epidermal cells and parenchyma cells, while, promoting cell division of subepidermal cells. Additionally, CPPU significantly increased the gibberellin and cytokinin biosynthetic pathway and signaling, while repressing auxin and ABA biosynthetic pathway; thus, signaling plays an essential role in CPPU controlling kiwifruit development. Notably, transcriptomic analysis revealed that a total of 2244 genes, including 352 unannotated genes, were differentially expressed in kiwifruits because of CPPU treatment, including 127 transcription factors. These genes are mainly enriched in plant hormone signal transduction, photosynthesis, MAPK signaling pathway, starch and sucrose metabolism, and phenylpropanoid biosynthesis. Overall, our results highlight that CPPU regulation of kiwifruit development is mainly associated with an antagonistic and/or synergistic regulatory role of endogenous phytohormones, and enhancing the energy supply. This provides new insights into the molecular details of CPPU controlling kiwifruit development at the fastest fruit growth stage, which is of agricultural importance for kiwifruit breeding and crop improvement.

Comparison of volatile components in fresh and dried Zanthoxylum bungeanum Maxim.

Fresh and dried Zanthoxylum bungeanum Maxim volatiles of two main cultivars including Dahongpao and Meihuajiao, were determined through GC-MS and compared. In all the tested samples, linalool, d-limonene, eucalyptol, 3-nonanone, and ß-myrcene were identified as the five predominant components. The percentages of these components in fresh Dahongpao were 23.89%, 21.04%, 7.46%, 5.63% and 5.87%, respectively. Similar percentages, 27.28%, 17.62%, 6.39%, 1.66% and 7.8%, were found in dried Dahongpao. In general, the contents of linalool and ß-myrcene in dried Dahongpao and Meihuajiao were slightly higher than those in fresh samples, whereas the contents of d-limonene, eucalyptol, and 3-nonanone were lower. Partial least squares discriminant analysis results showed that the two cultivars could be clearly differentiated based on volatiles, whereas, the fresh and dried Zanthoxylum bungeanum Maxim samples could not. This demonstrated that the drying process had no significant effect on the volatiles.

Transcriptome analysis reveals the genetic basis underlying the biosynthesis of volatile oil, gingerols, and diarylheptanoids in ginger (Zingiber officinale Rosc.).

BACKGROUND: Ginger (Zingiber officinale Rosc.) is a popular flavoring that widely used in Asian, and the volatile oil in ginger rhizomes adds a special fragrance and taste to foods. The bioactive compounds in ginger, such as gingerols, diarylheptanoids, and flavonoids, are of significant value to human health because of their anticancer, anti-oxidant, and anti-inflammatory properties. However, as a non-model plant, knowledge about the genome sequences of ginger is extremely limited, and this limits molecular studies on this plant. In this study, de novo transcriptome sequencing was performed to investigate the expression of genes associated with the biosynthesis of major bioactive compounds in matured ginger rhizome (MG), young ginger rhizome (YG), and fibrous roots of ginger (FR). RESULTS: A total of 361,876 unigenes were generated by de novo assembly. The expression of genes involved in the pathways responsible for the biosynthesis of major bioactive compounds differed between tissues (MG, YG, and FR). Two pathways that give rise to volatile oil, gingerols, and diarylheptanoids, the "terpenoid backbone biosynthesis" and "stilbenoid, diarylheptanoid and gingerol biosynthesis" pathways, were significantly enriched (adjusted P value < 0.05) for differentially expressed genes (DEGs) (FDR < 0.005) both between the FR and YG libraries, and the FR and MG libraries. Most of the unigenes mapped in these two pathways, including curcumin synthase, phenylpropanoylacetyl-CoA synthase, trans-cinnamate 4-monooxygenase, and 4-hydroxy-3-methylbut-2-en-1-yl diphosphate synthase, were expressed to a significantly higher level (log2 (fold-change) ≥ 1) in FR than in YG or MG. CONCLUSION: This study provides the first insight into the biosynthesis of bioactive compounds in ginger at a molecular level and provides valuable genome resources for future molecular studies on ginger. Moreover, our results establish that bioactive compounds in ginger may predominantly synthesized in the root and then transported to rhizomes, where they accumulate.

Transcriptome Analysis Reveals the Mechanism Underlying the Production of a High Quantity of Chlorogenic Acid in Young Leaves of Lonicera macranthoides Hand.-Mazz.

Lonicera macranthoides Hand.-Mazz (L. macranthoides) is a medicinal herb that is widely distributed in southern China. The biosynthetic and metabolic pathways for a core secondary metabolite in L. macranthoides, chlorogenic acid (CGA), have been elucidated in many species. However, the mechanisms of CGA biosynthesis and the related gene regulatory network in L. macranthoides are still not well understood. In this study, CGA content was quantified by high performance liquid chromatography (HPLC), and CGA levels differed significantly among three tissues; specifically, the CGA content in young leaves (YL) was greater than that in young stems (YS), which was greater than that in mature flowers (MF). Transcriptome analysis of L. macranthoides yielded a total of 53,533,014 clean reads (average length 90 bp) and 76,453 unigenes (average length 703 bp). A total of 3,767 unigenes were involved in biosynthesis pathways of secondary metabolites. Of these unigenes, 80 were possibly related to CGA biosynthesis. Furthermore, differentially expressed genes (DEGs) were screened in different tissues including YL, MF and YS. In these tissues, 24 DEGs were found to be associated with CGA biosynthesis, including six phenylalanine ammonia lyase (PAL) genes, six 4-coumarate coenzyme A ligase (4CL) genes, four cinnamate 4-Hydroxylase (C4H) genes, seven hydroxycinnamoyl transferase/hydroxycinnamoyl-CoA quinate transferase HCT/HQT genes and one coumarate 3-hydroxylase (C3H) gene.These results further the understanding of CGA biosynthesis and the related regulatory network in L. macranthoides.

Comparative transcriptomic analysis of the response to cold acclimation in Eucalyptus dunnii.

Eucalyptus dunnii is an important macrophanerophyte with high economic value. However, low temperature stress limits its productivity and distribution. To study the cold response mechanisms of E. dunnii, 5 cDNA libraries were constructed from mRNA extracted from leaves exposed to cold stress for varying lengths of time and were evaluated by RNA-Seq analysis. The assembly of the Illumina datasets was optimized using various assembly programs and parameters. The final optimized assembly generated 205,325 transcripts with an average length of 1,701 bp and N50 of 2,627 bp, representing 349.38 Mb of the E. dunnii transcriptome. Among these transcripts, 134,358 transcripts (65.4%) were annotated in the Nr database. According to the differential analysis results, most transcripts were up-regulated as the cold stress prolonging, suggesting that these transcripts may be involved in the response to cold stress. In addition, the cold-relevant GO categories, such as 'response to stress' and 'translational initiation', were the markedly enriched GO terms. The assembly of the E. dunnii gene index and the GO classification performed in this study will serve as useful genomic resources for the genetic improvement of E. dunnii and also provide insights into the molecular mechanisms of cold acclimation in E. dunnii.

Molecular cloning and expression of Hedychium coronarium farnesyl pyrophosphate synthase gene and its possible involvement in the biosynthesis of floral and wounding/herbivory induced leaf volatile sesquiterpenoids.

Farnesyl pyrophosphate synthase (FPPS EC 2.5.1.10) catalyzes the production of farnesyl pyrophosphate (FPP), which is a key precursor for many sesquiterpenoids such as floral scent and defense volatiles against herbivore attack. Here we report a new full-length cDNA encoding farnesyl diphosphate synthase from Hedychium coronarium. The open reading frame for full-length HcFPPS encodes a protein of 356 amino acids, which is 1068 nucleotides long with calculated molecular mass of 40.7 kDa. Phylogenetic tree analysis indicates that HcFPPS belongs to the plant FPPS super-family and has strong relationship with FPPS from Musa acuminata. Expression of the HcFPPS gene in Escherichia coli yielded FPPS activity. Tissue-specific and developmental analyses of the HcFPPS mRNA and corresponding volatile sesquiterpenoid levels in H. coronarium flowers revealed that the HcFPPS might play a regulatory role in floral volatile sesquiterpenoid biosynthesis. The emission of the FPP-derived volatile terpenoid correlates with strong expression of HcFPPS induced by mechanical wounding and Udaspes folus-damage in leaves, which suggests that HcFPPS may have an important ecological function in H. coronarium vegetative organ.