RESUMEN
Biochar amendment is a promising strategy for mitigating antibiotic resistance genes (ARGs) in soil and plants, but its effects on ARGs at field scale are not fully understood. Here, field trials were executed utilizing two plant varieties, Brassica juncea and Lolium multiflorum, with four types of biochar to investigate changes in ARGs and microbiome in soil, rhizosphere, root endophytes, and leaf endophytes. Results showed that biochar altered ARG distribution in soil and plant, and restrained their transmission from soil and rhizosphere to endophytes. A reduction of 1.2-2.2 orders of magnitude in the quantity of ARGs was observed in root and leaf endophytes following biochar addition, while no significant changes were observed in soil and rhizosphere samples. Procrustes and network analyses revealed significant correlations between microbial communities and mobile genetic elements with ARGs (P < 0.05). Besides, redundancy and variation partitioning analysis indicated that bacterial communities may play a dominant role in shaping the ARGs profile, contributing to 43 % of the variation observed in ARGs. These field results suggest that biochar amendment alone may not fully alleviate ARGs in soil, but it has a significant beneficial impact on food safety and human health by effectively reducing ARGs in plant endophytes.
Asunto(s)
Carbón Orgánico , Farmacorresistencia Microbiana , Microbiota , Rizosfera , Microbiología del Suelo , Microbiota/efectos de los fármacos , Microbiota/genética , Farmacorresistencia Microbiana/genética , Lolium/microbiología , Lolium/genética , Lolium/efectos de los fármacos , Suelo/química , Planta de la Mostaza/genética , Planta de la Mostaza/microbiología , Bacterias/genética , Bacterias/efectos de los fármacos , Raíces de Plantas/microbiología , Endófitos/genética , Endófitos/efectos de los fármacos , Genes Bacterianos , Hojas de la Planta/microbiologíaRESUMEN
The addition of plant-growth-promoting bacteria (PGPB) to heavy-metal-contaminated soils can significantly improve plant growth and productivity. This study isolated heavy-metal-tolerant bacteria with growth-promoting traits and investigated their inoculation effects on the germination rates and growth of millet (Panicum miliaceum) and mustard (Brassica juncea) in Cd- and Zn-contaminated soil. Leifsonia sp. ZP3, which is resistant to Cd (0.5 mM) and Zn (1 mM), was isolated from forest soil. The ZP3 strain exhibited plant-growth-promoting activity, including indole-3-acetic acid production, phosphate solubilization, catalase activity, and 2,2-diphenyl-1-picrylhydrazyl radical scavenging. In soil contaminated with low concentrations of Cd (0.232 ± 0.006 mM) and Zn (6.376 ± 0.256 mM), ZP3 inoculation significantly increased the germination rates of millet and mustard 8.35- and 31.60-fold, respectively, compared to the non-inoculated control group, while the shoot and root lengths of millet increased 1.77- and 4.44-fold (p < 0.05). The chlorophyll content and seedling vigor index were also 4.40 and 18.78 times higher in the ZP3-treated group than in the control group (p < 0.05). The shoot length of mustard increased 1.89-fold, and the seedling vigor index improved 53.11-fold with the addition of ZP3 to the contaminated soil (p < 0.05). In soil contaminated with high concentrations of Cd and Zn (0.327 ± 0.016 and 8.448 ± 0.250 mM, respectively), ZP3 inoculation led to a 1.98-fold increase in the shoot length and a 2.07-fold improvement in the seedling vigor index compared to the control (p < 0.05). The heavy-metal-tolerant bacterium ZP3 isolated in this study thus represents a promising microbial resource for improving the efficiency of phytoremediation in Cd- and Zn-contaminated soil.
Asunto(s)
Biodegradación Ambiental , Cadmio , Germinación , Planta de la Mostaza , Panicum , Microbiología del Suelo , Contaminantes del Suelo , Zinc , Planta de la Mostaza/microbiología , Planta de la Mostaza/crecimiento & desarrollo , Contaminantes del Suelo/metabolismo , Cadmio/metabolismo , Zinc/metabolismo , Panicum/microbiología , Panicum/crecimiento & desarrollo , Raíces de Plantas/microbiología , Raíces de Plantas/crecimiento & desarrollo , Metales Pesados/metabolismo , Suelo/química , Ácidos Indolacéticos/metabolismoRESUMEN
Cd is highly mobile, non-essential trace element, that has become serious environmental issue due to its elevated concentration in soil. The present study was taken up to work out salutary effect of melatonin (Mlt) and PGPR ((Pseudomonas putida (Pp), Pseudomonas fluorescens (Pf) in 10 days old Cd stressed (0.3 mM) Brassica juncea L. seedlings. The present work investigated growth characteristics, photosynthetic pigments, secondary metabolites in melatonin-PGPR inoculated B. juncea seedlings. It was backed by molecular studies entailing RT-PCR and transcriptomic analyses. Our results revealed, substantial increase in photosynthetic pigments and secondary metabolites, after treatment with melatonin, P.putida, P. fluorescens in Cd stressed B. juncea seedlings, further validated with transcriptome analysis. Comparative transcriptome analyses identified 455, 5953, 3368, 2238 upregulated and 4921, 430, 137, 27 down regulated DEGs, Cn-vs-Cd, Cd-vs-Mlt, Cd-vs-Mlt-Pp-Pf, Cd-vs-Mlt-Pp-Pf-Cd comparative groups respectively. In depth exploration of genome analyses (Gene ontology, Kyoto encyclopaedia of genes), revealed that Cd modifies the expression patterns of most DEGs mainly associated to photosystem and chlorophyll synthesis. Also, gene expression studies for key photosynthetic genes (psb A, psb B, CHS, PAL, and PSY) suggested enhanced expression in melatonin-rhizobacteria treated Cd stressed B. juncea seedlings. Overall, results provide new insights into probable mechanism of Mlt-PGPR induced protection to photosynthesis in Cd stressed B. juncea plants.
Asunto(s)
Cadmio , Melatonina , Planta de la Mostaza , Fotosíntesis , Transcriptoma , Melatonina/farmacología , Planta de la Mostaza/efectos de los fármacos , Planta de la Mostaza/genética , Planta de la Mostaza/microbiología , Planta de la Mostaza/metabolismo , Planta de la Mostaza/crecimiento & desarrollo , Fotosíntesis/efectos de los fármacos , Cadmio/toxicidad , Transcriptoma/efectos de los fármacos , Regulación de la Expresión Génica de las Plantas/efectos de los fármacos , Contaminantes del Suelo/toxicidad , Plantones/efectos de los fármacos , Pseudomonas putida/efectos de los fármacos , Pseudomonas putida/genética , Pseudomonas putida/metabolismoRESUMEN
MAIN CONCLUSION: The study evaluates the potential of Spray-Induced Gene Silencing and Host-Induced Gene Silencing for sustainable crop protection against the broad-spectrum necrotrophic fungus Sclerotinia sclerotiorum. Sclerotinia sclerotiorum (Lib.) de Bary, an aggressive ascomycete fungus causes white rot or cottony rot on a broad range of crops including Brassica juncea. The lack of sustainable control measures has necessitated biotechnological interventions such as RNA interference (RNAi) for effective pathogen control. Here we adopted two RNAi-based strategies-Spray-Induced Gene Silencing (SIGS) and Host-Induced Gene Silencing (HIGS) to control S. sclerotiorum. SIGS was successful in controlling white rot on Nicotiana benthamiana and B. juncea by targeting SsPac1, a pH-responsive transcription factor and SsSmk1, a MAP kinase involved in fungal development and pathogenesis. Topical application of dsRNA targeting SsPac1 and SsSmk1 delayed infection initiation and progression on B. juncea. Further, altered hyphal morphology and reduced radial growth were also observed following dsRNA application. We also explored the impact of stable dsRNA expression in A. thaliana against S. sclerotiorum. In this report, we highlight the utility of RNAi as a biofungicide and a tool for preliminary functional genomics.
Asunto(s)
Ascomicetos , Nicotiana , Enfermedades de las Plantas , Interferencia de ARN , Ascomicetos/fisiología , Ascomicetos/genética , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/prevención & control , Nicotiana/genética , Nicotiana/microbiología , Planta de la Mostaza/genética , Planta de la Mostaza/microbiología , Proteínas Fúngicas/genética , Proteínas Fúngicas/metabolismo , Arabidopsis/genética , Arabidopsis/microbiología , Factores de Transcripción/genética , Factores de Transcripción/metabolismo , ARN Bicatenario/genéticaRESUMEN
Brassica carinata (BBCC) commonly referred to as Ethiopian mustard is a natural allotetraploid containing the genomes of Brassica nigra (BB) and Brassica oleracea (CC). It is an oilseed crop endemic to the northeastern regions of Africa. Although it is under limited cultivation, B. carinata is valuable as it is resistant/highly tolerant to most of the pathogens affecting widely cultivated Brassica species of the U's triangle. We report a chromosome-scale genome assembly of B. carinata accession HC20 using long-read Oxford Nanopore sequencing and Bionano optical maps. The assembly has a scaffold N50 of ~39.8 Mb and covers ~1.11 Gb of the genome. We compared the long-read genome assemblies of the U's triangle species and found extensive gene collinearity between the diploids and allopolyploids with no evidence of major gene losses. Therefore, B. juncea (AABB), B. napus (AACC), and B. carinata can be regarded as strict allopolyploids. We cataloged the nucleotide-binding and leucine-rich repeat immune receptor (NLR) repertoire of B. carinata and, identified 465 NLRs, and compared these with the NLRs in the other Brassica species. We investigated the extent and nature of early-generation genomic interactions between the constituent genomes of B. carinata and B. juncea in interspecific crosses between the two species. Besides the expected recombination between the constituent B genomes, extensive homoeologous exchanges were observed between the A and C genomes. Interspecific crosses, therefore, can be used for transferring disease resistance from B. carinata to B. juncea and broadening the genetic base of the two allotetraploid species.
Asunto(s)
Brassica , Cromosomas de las Plantas , Resistencia a la Enfermedad , Genoma de Planta , Planta de la Mostaza , Enfermedades de las Plantas , Resistencia a la Enfermedad/genética , Planta de la Mostaza/genética , Planta de la Mostaza/microbiología , Enfermedades de las Plantas/genética , Enfermedades de las Plantas/microbiología , Enfermedades de las Plantas/inmunología , Genoma de Planta/genética , Brassica/genética , Brassica/microbiología , Cromosomas de las Plantas/genética , Introgresión Genética , PoliploidíaRESUMEN
Heavy metals are one of the most damaging environmental toxins that hamper growth of plants. These noxious chemicals include lead (Pb), arsenic (As), nickel (Ni), cadmium (Cd) and chromium (Cr). Chromium is one of the toxic metal which induces various oxidative processes in plants. The emerging role of nanoparticles as pesticides, fertilizers and growth regulators have attracted the attention of various scientists. Current study was conducted to explore the potential of zinc oxide nanoparticles (ZnONPs) alone and in combination with plant growth promoting rhizobacteria (PGPR) Klebsiella sp. SBP-8 in Cr stress alleviation in Brassica juncea (L.). Chromium stress reduced shoot fresh weight (40%), root fresh weight (28%), shoot dry weight (28%) and root dry weight (34%) in B. juncea seedlings. Chromium stressed B. juncea plants showed enhanced levels of malondialdehyde (MDA), electrolyte leakage (EL), hydrogen peroxide (H2O2) and superoxide ion (O2⢠-). However, co-supplementation of ZnONPs and Klebsiella sp. SBP-8 escalated the activity of antioxidant enzymes i.e., superoxide dismutase (SOD), catalase (CAT), ascorbate peroxidase (APX) in B. juncea grown in normal and Cr-toxic soil. It is further proposed that combined treatment of ZnONPs and Klebsiella sp. SBP-8 may be useful for alleviation of other abiotic stresses in plants.
Asunto(s)
Antioxidantes , Cromo , Klebsiella , Planta de la Mostaza , Óxido de Zinc , Planta de la Mostaza/efectos de los fármacos , Planta de la Mostaza/microbiología , Planta de la Mostaza/metabolismo , Cromo/toxicidad , Cromo/metabolismo , Antioxidantes/metabolismo , Klebsiella/metabolismo , Klebsiella/efectos de los fármacos , Óxido de Zinc/farmacología , Adsorción , Nanopartículas del Metal/química , Nanopartículas/química , Contaminantes del Suelo/toxicidadRESUMEN
BACKGROUND: Zha cai, a pickled vegetable with unique flavors, is produced by fermenting fresh mustard tubers. In this study, the main physicochemical indices and volatile flavor compounds were determined in three fermentation periods. The bacterial and fungal communities in the three fermentation periods of zha cai were also monitored using high-throughput sequencing. Key microbial communities were identified based on significant correlations with flavor substances. RESULTS: Firmicutes and Proteobacteria were the main bacterial phyla found within the three fermentation periods. Lactic acid bacteria, namely Lactobacillus, was the predominant bacteria found at the genus level. Ascomycetes and Stenotrophomonas were the major fungal phyla found in the three fermentation periods. Yeast, namely Debaryomyces, was the predominant fungus found at the genus level. A total of 42 bacterial genera were negatively correlated with volatile flavor substances of zha cai, and 37 bacterial genera were positively correlated. Meanwhile, a total of 47 genera of fungi were negatively correlated with the volatile flavor substances of zha cai, while 50 genera were positively correlated. Several microbial genera were significantly correlated with volatile flavor compounds, including Lactobacillus, Halomonas, Rhodococcus, and Debaryomyces. CONCLUSION: This study identified the microbial classes that positively regulate the flavor of zha cai which could provide valuable help for flavor modulation in zha cai production. © 2024 Society of Chemical Industry.
Asunto(s)
Bacterias , Fermentación , Aromatizantes , Hongos , Microbiota , Compuestos Orgánicos Volátiles , Bacterias/clasificación , Bacterias/genética , Bacterias/metabolismo , Bacterias/aislamiento & purificación , Aromatizantes/metabolismo , Aromatizantes/química , Compuestos Orgánicos Volátiles/metabolismo , Compuestos Orgánicos Volátiles/química , Compuestos Orgánicos Volátiles/análisis , Hongos/metabolismo , Hongos/clasificación , Hongos/genética , Hongos/aislamiento & purificación , Planta de la Mostaza/microbiología , Planta de la Mostaza/química , Planta de la Mostaza/metabolismo , GustoRESUMEN
Here, we characterized the independent role of soil microbiomes (bacterial and fungal communities) in determining the flavor chemistry of harvested mustard seed (Brassica juncea). Given the known impacts of soil microbial communities on various plant characteristics, we hypothesized that differences in rhizosphere microbiomes would result in differences in seed flavor chemistry (glucosinolate content). In a glasshouse study, we introduced distinct soil microbial communities to mustard plants growing in an otherwise consistent environment. At the end of the plant life cycle, we characterized the rhizosphere and root microbiomes and harvested produced mustard seeds for chemical characterization. Specifically, we measured the concentrations of glucosinolates, secondary metabolites known to create spicy and bitter flavors. We examined associations between rhizosphere microbial taxa or genes and seed flavor chemistry. We identified links between the rhizosphere microbial community composition and the concentration of the main glucosinolate, allyl, in seeds. We further identified specific rhizosphere taxa predictive of seed allyl concentration and identified bacterial functional genes, namely genes for sulfur metabolism, which could partly explain the observed associations. Together, this work offers insight into the potential influence of the belowground microbiome on the flavor of harvested crops.