Proteo-metabolomic Dissection of Extracellular Matrix Reveals Alterations in Cell Wall Integrity and Calcium Signaling Governs Wall-Associated Susceptibility during Stem Rot Disease in Jute.

The plant surveillance system confers specificity to disease and immune states by activating distinct molecular pathways linked to cellular functionality. The extracellular matrix (ECM), a preformed passive barrier, is dynamically remodeled at sites of interaction with pathogenic microbes. Stem rot, caused by Macrophomina phaseolina, adversely affects fiber production in jute. However, how wall related susceptibility affects the ECM proteome and metabolome remains undetermined in bast fiber crops. Here, stem rot responsive quantitative temporal ECM proteome and metabolome were developed in jute upon M. phaseolina infection. Morpho-histological examination revealed that leaf shredding was accompanied by reactive oxygen species production in patho-stressed jute. Electron microscopy showed disease progression and ECM architecture remodeling due to necrosis in the later phase of fungal attack. Using isobaric tags for relative and absolute quantitative proteomics and liquid chromatography-tandem mass spectrometry, we identified 415 disease-responsive proteins involved in wall integrity, acidification, proteostasis, hydration, and redox homeostasis. The disease-related correlation network identified functional hubs centered on α-galactosidase, pectinesterase, and thaumatin. Gas chromatography-mass spectrometry analysis pointed toward enrichment of disease-responsive metabolites associated with the glutathione pathway, TCA cycle, and cutin, suberin, and wax metabolism. Data demonstrated that wall-degrading enzymes, structural carbohydrates, and calcium signaling govern rot responsive wall-susceptibility. Proteomics data were deposited in Pride (PXD046937; PXD046939).

Identification of Candidate Avirulence and Virulence Genes Corresponding to Stem Rust (Puccinia graminis f. sp. tritici) Resistance Genes in Wheat.

Stem rust, caused by the biotrophic fungal pathogen Puccinia graminis f. sp. tritici (Pgt), is an important disease of wheat. However, the majority of Pgt virulence/avirulence loci and underlying genes remain uncharacterized due to the constraints of developing bi-parental populations with this obligate biotroph. Genome-wide association studies (GWAS) using a sexual Pgt population mainly collected from the Pacific Northwestern United States were used to identify candidate virulence/avirulence effector genes corresponding to the six wheat Sr genes: Sr5, Sr21, Sr8a, Sr17, Sr9a, and Sr9d. The Pgt isolates were genotyped using whole-genome shotgun sequencing that identified approximately 1.2 million single nucleotide polymorphisms (SNPs) and were phenotyped at the seedling stage on six Sr gene differential lines. Association mapping analyses identified 17 Pgt loci associated with virulence or avirulence phenotypes on six Pgt resistance genes. Among these loci, 16 interacted with a specific Sr gene, indicating Sr-gene specific interactions. However, one avirulence locus interacted with two separate Sr genes (Sr9a and Sr17), suggesting two distinct Sr genes identifying a single avirulence effector. A total of 24 unique effector gene candidates were identified, and haplotype analysis suggests that within this population, AvrSr5, AvrSr21, AvrSr8a, AvrSr17, and AvrSr9a are dominant avirulence genes, while avrSr9d is a dominant virulence gene. The putative effector genes will be fundamental for future effector gene cloning efforts, allowing for further understanding of rust effector biology and the mechanisms underlying virulence evolution in Pgt with respect to race-specific R-genes. [Formula: see text] Copyright © 2024 The Author(s). This is an open access article distributed under the CC BY-NC-ND 4.0 International license.

Differential response of bacteria and fungi to drought on the decomposition of Sarcocornia fruticosa woody stems in a saline stream.

Inland saline ecosystems suffer multiple stresses (e.g., high radiation, salinity, water scarcity) that may compromise essential ecosystem functions such as organic matter decomposition. Here, we investigated the effects of drought on microbial colonization and decomposition of Sarcocornia fruticosa woody stems across different habitats in a saline watershed: on the dry floodplain, submerged in the stream channel and at the shoreline (first submerged, then emerged). Unexpectedly, weight loss was not enhanced in the submerged stems, while decomposition process differed between habitats. On the floodplain, it was dominated by fungi and high cellulolytic activity; in submerged conditions, a diverse community of bacteria and high ligninolytic activity dominated; and, on the shoreline, enzyme activities were like submerged conditions, but with a fungal community similar to the dry conditions. Results indicate distinct degradation paths being driven by different stress factors: strong water scarcity and photodegradation in dry conditions, and high salinity and reduced oxygen in wet conditions. This suggests that fungi are more resistant to drought, and bacteria to salinity. Overall, in saline watersheds, variations in multiple stress factors exert distinct environmental filters on bacteria and fungi and their role in the decomposition of plant material, affecting carbon cycling and microbial interactions.

Host cell wall composition and localized microenvironment implicated in resistance to basal stem degradation by lettuce drop (Sclerotinia minor).

BACKGROUND: Sclerotinia spp. are generalist fungal pathogens, infecting over 700 plant hosts worldwide, including major crops. While host resistance is the most sustainable and cost-effective method for disease management, complete resistance to Sclerotinia diseases is rare. We recently identified soft basal stem as a potential susceptibility factor to Sclerotinia minor infection in lettuce (Lactuca sativa) under greenhouse conditions. RESULTS: Analysis of stem and root cell wall composition in five L. sativa and one L. serriola accessions with varying growth habits and S. minor resistance levels revealed strong association between hemicellulose constituents, lignin polymers, disease phenotypes, and basal stem mechanical strength. Accessions resistant to basal stem degradation consistently exhibited higher levels of syringyl, guaiacyl, and xylose, but lower levels of fucose in stems. These findings suggest that stem cell wall polymers recalcitrant to breakdown by lignocellulolytic enzymes may contribute to stem strength-mediated resistance against S. minor. CONCLUSIONS: The lignin content, particularly guaiacyl and syringyl, along with xylose could potentially serve as biomarkers for identifying more resistant lettuce accessions and breeding lines. Basal stem degradation by S. minor was influenced by localized microenvironment conditions around the stem base of the plants.

Resurgence of wheat stem rust infections in western Europe: causes and how to curtail them.

Ten years ago, (black) stem rust - the most damaging of wheat (Triticum aestivum) rusts - re-emerged in western Europe. Disease incidences have since increased in scale and frequency. Here, we investigated the likely underlying causes and used those to propose urgently needed mitigating actions. We report that the first large-scale UK outbreak of the wheat stem rust fungus, Puccinia graminis f. sp. tritici (Pgt), in 2022 may have been caused by timely arrival of airborne urediniospores from southwest Europe. The drive towards later-maturing wheat varieties in the UK may be exacerbating Pgt incidences, which could have disastrous consequences. Indeed, infection assays showed that two UK Pgt isolates from 2022 could infect over 96% of current UK wheat varieties. We determined that the temperature response data in current disease risk simulation models are outdated. Analysis of germination rates for three current UK Pgt isolates showed substantial variation in temperature response functions, suggesting that the accuracy of disease risk simulations would be substantially enhanced by incorporating data from prevailing Pgt isolates. As Pgt incidences continue to accelerate in western Europe, we advocate for urgent action to curtail Pgt losses and help safeguard future wheat production across the region.

Modelling metabolic fluxes of tomato stems reveals that nitrogen shapes central metabolism for defence against Botrytis cinerea.

Among plant pathogens, the necrotrophic fungus Botrytis cinerea is one of the most prevalent, leading to severe crop damage. Studies related to its colonization of different plant species have reported variable host metabolic responses to infection. In tomato, high N availability leads to decreased susceptibility. Metabolic flux analysis can be used as an integrated method to better understand which metabolic adaptations lead to effective host defence and resistance. Here, we investigated the metabolic response of tomato infected by B. cinerea in symptomless stem tissues proximal to the lesions for 7 d post-inoculation, using a reconstructed metabolic model constrained by a large and consistent metabolic dataset acquired under four different N supplies. An overall comparison of 48 flux solution vectors of Botrytis- and mock-inoculated plants showed that fluxes were higher in Botrytis-inoculated plants, and the difference increased with a reduction in available N, accompanying an unexpected increase in radial growth. Despite higher fluxes, such as those involved in cell wall synthesis and other pathways, fluxes related to glycolysis, the tricarboxylic acid cycle, and amino acid and protein synthesis were limited under very low N, which might explain the enhanced susceptibility. Limiting starch synthesis and enhancing fluxes towards redox and specialized metabolism also contributed to defence independent of N supply.

Unveiling Fusaria mycoflora associated with natural occurrence of lisianthus wilt and stem rot in Central-highland Vietnam.

Wilt and stem rot (WSR) is an emerging syndrome threatening cut lisianthus (Eustoma russellianum) production in Lam Dong province, Vietnam. The disease was observed in all 13 inspected commercial lisianthus greenhouses across major lisianthus cultivation areas in Lam Dong, including Da Lat, Lac Duong, Don Duong, and Duc Trong, with incidence increasing with plant age, ranging from 7.5 to 32.4%. Infected plants displayed stunting, wilting, stem rot and blight, and dieback, with predominance of wilt and stem rot. The disease showed polycyclic behavior, with symptoms shifting from random or scattered in young plants to clustered patterns after the initial flower cutting. Forty-one Fusaria-like fungal isolates recovered from diseased lisianthus plants were identified as Fusarium vanleeuwenii (28 isolates), Neocosmospora solani (11 isolates), and F. annulatum (2 isolates) based on morphological observations and phylogenetic analysis of the internal transcribed spacer (ITS) region and translation elongation factor 1-alpha (TEF-1α) genes. The composition of Fusaria species varied across sites, with F. vanleeuwenii being consistently present. Pathogenicity tests confirmed that isolates of F. vanleeuwenii Li-Fo9511, N. solani Li-Fs4311, and F. annulatum Li-Fp3051 caused typical stem rot in in-vitro assays. In-planta assays showed wilting in seedlings starting two weeks post-infection, with a remarkable increase in disease incidence and severity between five and six weeks, particularly for F. vanleeuwenii Li-Fo9511. The pathogens were re-isolated and morphologically confirmed, fulfilling Koch's postulates. This is the first report of F. vanleeuwenii, N. solani, and F. annulatum as pathogens of lisianthus WSR in Vietnam, highlighting the need for effective control strategies.

Water retting process with hemp pre-treatment: effect on the enzymatic activities and microbial populations dynamic.

Proper retting process of hemp stems, in which efficient separation of cellulose fiber from the rest of the stem is promoted by indigenous microorganisms able to degrade pectin, is essential for fiber production and quality. This research aimed to investigate the effect of a pre-treatment dew retting in field of hemp stalks on the pectinolytic enzymatic activity and microbiota dynamic during lab-scale water retting process. A strong increase in the pectinase activity as well as in the aerobic and anaerobic pectinolytic concentration was observed from 14 to 21 days, especially using hemp stalks that were not subjected to a pre-retting treatment on field (WRF0 0.690 ± 0.05 U/mL). Results revealed that the microbial diversity significantly varied over time during the water retting and the development of microbiota characterizing the water retting of hemp stalks of different biosystems used in this study was affected by pre-treatment conditions in the field and water retting process and by an interaction between the two methods. Although at the beginning of the experiment a high biodiversity was recorded in all biosystems, the water retting led to a selection of microbial populations in function of the time of pre-treatment in field, especially in bacterial populations. The use of hemp stems did not subject to a field pre-treatment seems to help the development of a homogeneous and specific pectinolytic microbiota with a higher enzymatic activity in respect to samples exposed to uncontrolled environmental conditions for 10, 20, or 30 days before the water retting process. KEY POINTS: • Microbial diversity significantly varied over time during water retting. • Water retting microbiota was affected by dew pre-treatment in the field. • Retting of no pretreated hemp allows the development of specific microbiota with high enzymatic activity.

Surviving the Potato Stems: Differences in Genes Required for Fitness by Dickeya dadantii and Dickeya dianthicola.

Bacteria belonging to the genus Dickeya cause blackleg and soft rot symptoms on many plant hosts, including potato. Although there is considerable knowledge about the genetic determinants that allow Dickeya to colonize host plants, as well as the genes that contribute to virulence, much is still unknown. To identify the genes important for fitness in potato stems, we constructed and evaluated randomly barcoded transposon mutant (RB-TnSeq) libraries of Dickeya dadantii and Dickeya dianthicola. We identified 169 and 157 genes important for growth in D. dadantii and D. dianthicola in stems, respectively. This included genes related to metabolic pathways, chemotaxis and motility, transcriptional regulation, transport across membranes, membrane biogenesis, detoxification mechanisms, and virulence-related genes, including a potential virulence cluster srfABC, c-di-GMP modulating genes, and pectin degradation genes. When we compared the results of the stem assay with other datasets, we identified genes important for growth in stems versus tubers and in vitro conditions. Additionally, our data showed differences in fitness determinants for D. dadantii and D. dianthicola. These data provide important insights into the mechanisms used by Dickeya when interacting with and colonizing plants and thus might provide targets for management.

Effective Control of Sclerotinia Stem Rot in Canola Plants Through Application of Exogenous Hairpin RNA of Multiple Sclerotinia sclerotiorum Genes.

Sclerotinia stem rot is a globally destructive plant disease caused by Sclerotinia sclerotiorum. Current management of Sclerotinia stem rot primarily relies on chemical fungicides and crop rotation, raising environmental concerns. In this study, we developed an eco-friendly RNA bio-fungicide targeting S. sclerotiorum. Six S. sclerotiorum genes were selected for double-stranded RNA (dsRNA) synthesis. Four genes, a chitin-binding domain, mitogen-activated protein kinase, oxaloacetate acetylhydrolase, and abhydrolase-3, were combined to express hairpin RNA in Escherichia coli HT115. The effect of application of total RNA extracted from E. coli HT115 expressing hairpin RNA on disease progressive and necrosis lesions was evaluated. Gene expression analysis using real-time PCR showed silencing of the target genes using 5 ng/µl of dsRNA in a fungal liquid culture. A detached leaf assay and greenhouse application of dsRNA on canola stem and leaves showed variation in the reduction of necrosis symptoms by dsRNA of different genes, with abhydrolase-3 being the most effective. The dsRNA from a combination of four genes reduced disease severity significantly (P = 0.01). Plants sprayed with hairpin RNA from four genes had lesions that were almost 30% smaller than those of plants treated with abhydrolase-3 alone, in lab and greenhouse assays. The results of this study highlight the potential of RNA interference to manage diseases caused by S. sclerotiorum; however, additional research is necessary to optimize its efficacy.

Proclaiming Plant Growth-Promoting and Antifungal Properties of Pseudomonas lurida and Bacillus velezensis Isolated from Rhododendrons of Darjeeling Hills.

Endophytes have drawn attentions due to their effectiveness in providing benefits to host and non-host plants. In this study endophytic bacteria were isolated from stem and leaf samples of medicinally important plants Rhododendron griffithianum Wight and Rhododendron arboreum Smith subsp. cinnamomeum (Wall. ex G. Don) grown at higher altitudes of Darjeeling, India. Two endophytic bacteria, Pseudomonas lurida RGDS03 and Bacillus velezensis RCDL12 were identified based on 16S rRNA gene sequencing analysis. The endophytes exhibited indole acetic acid (IAA), gibberellic acid (GA), siderophore production, phosphate solubilization, nitrogen-fixing abilities, though B. velezensis RCDL12 showed superior production of IAA (126.04 ± 0.40 µg/mL), GA (241.00 ± 0.44 µg/mL), and phosphate (74.4 ± 0.41 µg/mL) solubilization as compared to P. lurida RGDS03. Purity of extracted IAA from these two endophytes was confirmed by HPLC and LC-MS analysis. In this study, P. lurida RGDS03 inhibited mycelial growth of two tested phytopathogens Phytophthora sp. and Pestalotiopsis sp. of broad host range. However, only against Pestalotiopsis sp. did B. velezensis RCDL12 exhibit antifungal activity. Study was conducted on growth promotion capabilities of isolates on rice and mung bean seedlings. P. lurida RGDS03, B. velezensis RCDL12 and consortium of both the strains reported with promising growth promotion on both rice (85-97%) and mung bean (86-99%) in terms of their seed germination, vegetative growth (root and shoot length, fresh and dry weight), and chlorophyll content as compared to the control plants (untreated). This study has emphasized growth-promoting and biocontrol activities of endophytic bacteria from rhododendrons, and application to enhance crop development for sustainable agriculture.

Multiple Forms of Resistance to the Phomopsis Stem Canker Pathogens Diaporthe helianthi and D. gulyae in Sunflower.

Phomopsis stem canker of cultivated sunflower (Helianthus annuus L.) can be caused by multiple necrotrophic fungi in the genus Diaporthe, with Diaporthe helianthi and D. gulyae being the most common causal agents in the United States. Infection begins at the leaf margins and proceeds primarily through the vasculature, progressing from the leaf through the petiole to the stem, resulting in formation of brown stem lesions centered around the petiole. Sunflower resistance to Phomopsis stem canker is quantitative and genetically complex. Due to the intricate disease process, resistance is possible at different stages of infection, and multiple forms of defense may contribute to the overall level of quantitative resistance. In this study, sunflower lines exhibiting field resistance to Phomopsis stem canker were evaluated for stem and leaf resistance to multiple isolates of D. helianthi and D. gulyae in greenhouse experiments, and responses to the two species were compared. Additionally, selected resistant and susceptible lines were evaluated for petiole transmission resistance to D. helianthi. Lines with distinct forms of resistance were identified, and results indicated that responses to stem inoculation were strongly correlated (Spearman's coefficient 0.598, P < 0.001) for the two fungal species, while leaf responses were not (Spearman's coefficient 0.396, P = 0.076). These results provide a basis for genetic dissection of distinct forms of sunflower resistance to Phomopsis stem canker and will facilitate combining different forms of resistance to potentially achieve durable control of this disease in sunflower hybrids.

Fusarium amaranthi sp. nov. from Amaranth Is an Emergent Species Closely Related to F. circinatum.

Amaranth (Amaranthus spp. L) is not native to South Korea but is cultivated in small scales for ornamental purposes as well as leafy vegetables and pseudo cereals. In this study, a new species within the genus Fusarium was isolated from amaranth, showing stem rot symptoms from a farmer field in Hwaseong, South Korea. The disease is characterized by dark-brown spots with black borders, leading to withering. Phylogenetic analysis-based concatenated sequences of translation elongation factor 1-alpha (TEF1), beta-tubulin (tub2), calmodulin (cmdA), RNA polymerase largest subunit (RPB1), and RNA polymerase II second largest subunit (RPB2) genes revealed that the obtained isolates formed a distinct clad within the Fusarium fujikuroi species complex and is closely related to F. circinatum. Cultural and morphological characteristics and pathogenicity on healthy amaranth plants (stem and leaves) were examined. The isolates readily differentiated from F. circinatum based on one- to five-septate macroconidia and the absence of sterile hyphae. Based on molecular and morphological characteristics, this fungus is demonstrated to be a new species and is described here as F. amaranthi, the causal agent of stem rot of amaranth in South Korea.

Effective, Consistent, and Rapid Noncontact Application Methods for Seedling Basal Stem Infection by Sclerotinia sclerotiorum.

Sclerotinia sclerotiorum (Lib.) de Bary, an economically devastating soilborne fungal pathogen known to cause disease across a wide range of plants, produces long-term inoculum called sclerotia that can germinate either carpogenically by ascospores infecting aboveground plant parts or myceliogenically to infect stem base and roots. Typically, for research purposes, S. sclerotiorum diseases are initiated by direct contact methods, using S. sclerotiorum mycelium agar plugs wrapped around the stem or sclerotia placed directly beneath root mass. However, reproducible noncontact methods leading to basal stem infection are not currently available. Therefore, the objective of this study was to develop effective noncontact protocols that consistently generate basal plant stem infection from S. sclerotiorum in the soil. Using three host plant species (canola, lupin, and lettuce), we determined two methods that reliably produced basal stem infection. The first method, where mycelial agar plugs were positioned just below the soil surface at a distance of 5 mm from each seedling, led to 100% infection in all plants. The second method used pathogen-infested soil by mixing the soil with dry inoculum in the form of a powder prepared from mycelium-colonized organic substrates. Four substrates consistently produced 100% seedling infection at 4 days after inoculation (DAI): wheat bran, wheat grain, red rice, and hulled millet. In contrast, chia, canary, sesame, and ryegrass seed substrates resulted in less than 50% seedling infection at 10 DAI, and infection levels did not progress further. The two soil inoculation methods outlined in this study will enhance future research on the progression of S. sclerotiorum diseases, with the potential to screen disease-resistant host genotypes to basal S. sclerotiorum infection and, in particular, to test the effectiveness of soil applications of fungicides or biocontrol agents against S. sclerotiorum basal infection.

Effect of Fungicide and Timing of Application on Management of Phoma Black Stem of Cultivated Sunflowers in the United States.

Phoma black stem (PBS), caused by Phoma macdonaldii Boerema (teleomorph Leptosphaeria lindquistii Frezzi), is the most common stem disease of sunflower (Helianthus annuus L.) in the northern Great Plains region of the United States. However, the impact of PBS on sunflower yield in the United States is unclear, and a near complete absence of information on the impact of fungicides on disease management exists. The objectives of this study were to determine the impact of PBS on sunflower yield, the efficacy of available fungicides, the optimal fungicide application timing, and the economic viability of fungicides as a management tool. Fungicide timing efficacy was evaluated by applying single and/or sequential applications of pyraclostrobin fungicide at three sunflower growth stages in 10 field trials between 2017 and 2019. Efficacy of 10 fungicides from the Fungicide Resistance Action Committee (FRAC) groups 3, 7, and 11 were evaluated in four field trials between 2018 and 2019. The impact of treatments on PBS were evaluated by determination of incidence, severity, maximum lesion height, disease severity index (DSI), and harvested yield. Nine of the 10 fungicides evaluated and all fungicide timings that included an early bud application resulted in disease reductions when compared with the nontreated controls. The DSI was negatively correlated to sunflower yield in high-yield environments (P = 0.0004; R2 = 0.3425) but not in low- or moderate-yield environments. Although FRAC 7 fungicides were generally most efficacious, the sufficient efficacy and lower cost of FRAC 11 fungicides make them more economically viable in high-yielding environments at current market conditions.

Effect of Fungicide Application and Corn Hybrid Class on the Presence of Fusarium graminearum and the Concentration of Deoxynivalenol in Ear and Stalk Parts of Corn (Zea mays) Used for Silage.

In Wisconsin, the use of brown midrib (BMR) corn (Zea mays) hybrids for ensiling and subsequent feeding to dairy cows is quite common. The overall milk production from cows fed silage from BMR hybrids is typically higher than those fed silage made from dual-purpose hybrids. Gibberella diseases (ear and stalk rot) caused by Gibberella zeae (anamorph; Fusarium graminearum) and the accompanying accumulation of the mycotoxin deoxynivalenol (DON) can be significant issues during the field production of BMR hybrids. The work presented here aimed to understand the role of hybrid class on the distribution of F. graminearum DNA and DON in the ear and stalk parts of corn for silage. An ear and stalk partitioned sample experiment was conducted on silage corn from field trials in Arlington, Wisconsin, in 2020 and 2021. The trials were arranged in a randomized complete block design in both years, including one BMR hybrid, one dual-purpose hybrid, and seven fungicide application regimes. Paired ear and stalk samples were physically separated, dried, and ground at harvest before determining the concentration of F. graminearum DNA and DON in each sample. Across both years, the main effects of hybrid, treatment, and plant part were not significant (P > 0.1) on DON concentration. However, the hybrid-by-plant part interaction effect was significant (P < 0.01). Ears of the BMR hybrid accumulated the most DON, whereas the dual-purpose hybrid ears had the lowest DON concentration. The concentrations of DON and F. graminearum DNA were significantly (P < 0.01) and highly correlated in the ear (r = 0.73) but not in the stalk (r = 0.09, P = 0.33). These findings suggest that DON accumulation in the corn ear is a major contributor in the difference observed in the total DON between the hybrid classes. Therefore, growers and researchers are encouraged to focus production and breeding on hybrids in both classes that accumulate less DON in ears, resulting in lower total DON in corn chopped for silage.

Agave Wilt Susceptibility by Reduction of Free Hexoses in Root Tissue of Agave tequilana Weber var. azul Commercial Plants in the Fructan Accumulation Process.

Agave tequilana stems store fructan polymers, the main carbon source for tequila production. This crop takes six or more years for industrial maturity. In conducive conditions, agave wilt disease increases the incidence of dead plants after the fourth year. Plant susceptibility induced for limited photosynthates for defense is recognized in many crops and is known as "sink-induced loss of resistance". To establish whether A. tequilana is more prone to agave wilt as it ages, because the reduction of water-soluble carbohydrates in roots, as a consequence of greater assembly of highly polymerized fructans, were quantified roots sucrose, fructose, and glucose, as well as fructans in stems of agave plants of different ages. The damage induced by inoculation with Fusarium solani or F. oxysporum in the roots or xylem bundles, respectively, was recorded. As the agave plant accumulated fructans in the stem as the main sink, the amount of these hexoses diminished in the roots of older plants, and root rot severity increased when plants were inoculated with F. solani, as evidence of more susceptibility. This knowledge could help to structure disease management that reduces the dispersion of agave wilt, dead plants, and economic losses at the end of agave's long crop cycle.

Straw Incorporation with Exogenous Degrading Bacteria (ZJW-6): An Integrated Greener Approach to Enhance Straw Degradation and Improve Rice Growth.

Rice straw is an agricultural waste, the disposal of which through open burning is an emerging challenge for ecology. Green manufacturing using straw returning provides a more avant-garde technique that is not only an effective management measure to improve soil fertility in agricultural ecosystems but also nurtures environmental stewardship by reducing waste and the carbon footprint. However, fresh straw that is returned to the field cannot be quickly decomposed, and screening microorganisms with the capacity to degrade straw and understanding their mechanism of action is an efficient approach to solve such problems. This study aimed to reveal the potential mechanism of influence exerted by exogenous degradative bacteria (ZJW-6) on the degradation of straw, growth of plants, and soil bacterial community during the process of returning rice straw to the soil. The inoculation with ZJW-6 enhanced the driving force of cellulose degradation. The acceleration of the rate of decomposition of straw releases nutrients that are easily absorbed by rice (Oryza sativa L.), providing favorable conditions for its growth and promoting its growth and development; prolongs the photosynthetic functioning period of leaves; and lays the material foundation for high yields of rice. ZJW-6 not only directly participates in cellulose degradation as degrading bacteria but also induces positive interactions between bacteria and fungi and enriches the microbial taxa that were related to straw degradation, enhancing the rate of rice straw degradation. Taken together, ZJW-6 has important biological potential and should be further studied, which will provide new insights and strategies for the appropriate treatment of rice straw. In the future, this degrading bacteria may provide a better opportunity to manage straw in an ecofriendly manner.

Roseomonas populi sp. nov., an acetate-degrading bacteria isolated from the stem of Populus tomentosa.

Strain CN29T, isolated from the stem of 5- to 6-year-old Populus tomentosa in Shandong, China, was characterized using a polyphasic taxonomic approach. Cells of CN29T were Gram-stain negative, aerobic, nonspore-forming, and nonmotile coccoid. Growth occurred at 20-37 °C, pH 4.0-9.0 (optimum, pH 6.0), and with 0-1% NaCl (optimum, 1%). Phylogenetic analysis based on the 16S rRNA gene sequence indicated that strain CN29T was closely related to members of the genus Roseomonas and closest to Roseomonas pecuniae N75T (96.6%). This classification was further supported by phylogenetic analysis using additional core genes. The average nucleotide identity and digital DNA‒DNA hybridization values between strain CN29T and Roseomonas populi CN29T were 82.7% and 27.8%, respectively. The genome size of strain CN29T was 5.87 Mb, with a G + C content of 70.9%. The major cellular fatty acids included summed feature 8 (C18:1 ω7c/C18:1 ω6c), C19:0 cyclo ω8c and C16:0. The major respiratory quinone was Q-10. The polar lipids were phosphatidylcholine, aminolipid, phosphatidylglycerol, and diphosphatidylglycerol. Strain CN29T can utilize acetate as a carbon source for growth and metabolism. Additionally, it contains acid phosphatase (2-naphthyl phosphate), which catalyzes the hydrolysis of phosphoric monoesters. The CN29T strain contains several genes, including maeB, gdhB, and cysJ, involved in carbon, nitrogen, and sulfur cycling. These findings suggest that the strain may actively participate in ecosystem cycling, leading to soil improvement and promoting the growth of poplar trees. Based on the phylogenetic, phenotypic, and genotypic characteristics, strain CN29T is concluded to represent a novel species of the genus Roseomonas, for which the name Roseomonas populi sp. nov. is proposed. The type strain is CN29T (= JCM 35579T = GDMCC 1.3267T).

Flavobacterium endoglycinae sp. nov., an endophytic bacterium isolated from soybean (Glycine max L. cv. Gwangan) stems.

A Gram-stain-negative, facultatively anaerobic, motile by gliding, rod-shaped, oxidase- and catalase-positive bacterial strain, designated BB8T, was isolated from the stems of a Korean soybean cultivar (Glycine max L. cv. Gwangan). The strain produced a yellow pigment on tryptic soy agar. Growth of strain BB8T occurred at pH 5.0-8.0 (optimum, pH 7.0), at 10-35 °C (optimum, 25-30 °C) and in the presence of 0-1 % (w/v) NaCl (optimum, 0.5%). Phylogenetic analysis based on 16S rRNA gene sequences revealed that strain BB8T formed a lineage within the genus Flavobacterium and was most closely related to Flavobacterium artemisiae SYP-B1015T (96.9 % 16S rRNA gene sequence similarity) and Flavobacterium ustbae T13T (96.8%). The complete genome sequence of strain BB8T was 5 513 159 bp long with a G+C content of 34.1 mol%. The major fatty acids (>10 %) of strain BB8T were iso-C15 : 0 (21 %), summed feature 3 (comprising C16 : 1 ω7c and/or C16 : 1 ω6c, 20.3%) and iso-C16 : 0 3-OH (13.7%). The predominant polar lipids were phosphatidylethanolamine and unidentified aminolipids, and the major respiratory quinone was menaquinone-6. Based on these phenotypic, genotypic and chemotaxonomic characteristics, strain BB8T is considered to represent a novel species of the genus Flavobacterium, for which the name Flavobacterium endoglycinae sp. nov. is proposed. The type strain is BB8T (=KCTC 82167T=CCTCC AB 2020070T).