White rust disease elicited by the biotrophic pathogen
Albugo candida
is a leading cause of yield losses in oilseed
Brassica
crops, especially in the widely cultivated
Brassica juncea
. In the present investigation, the high-quality draft genome of a virulent Ac2V race of
A. candida
infecting
B. juncea
was sequenced using Illumina and Nanopore technologies. The raw data were assembled into a genome of 36.88 Mb with 415 scaffolds and N50 = 301.91 kb. The variant analysis showed 124,974 single nucleotide polymorphisms (SNPs) with an average density of 3.3 SNP per kb genome against the Ac2VPB reference assembly. Approximately 24.29% of the genome was constituted of repetitive elements, including 1,039 SSRs. A total number of 13,715 coding genes were revealed in the genome with an average distribution of 359.03 genes per Mb. Out of these predicted genes, 11,556 were annotated based on sequence homology and 355 were predicted as effectors with no transmembrane domain and N-terminal signal peptide. The annotation of 355 effectors revealed that 141 of them had homologs, while the remaining 214 were novel. Depending on the conserved motifs, these effectors were characterized, and their role in pathogenesis was established through qPCR in
B. juncea
. Additionally, phylogenetic analysis through average nucleotide identity revealed a similarity of 99.6% between the Canadian and Indian Ac2V isolate. Furthermore, 62 new contigs were identified in the Indian isolate that showed no sequence similarity to the Canadian isolate, suggesting variation within the race. Altogether, the present work provides genomic resources and framework for the dissection of this pathogen, which will refine our understanding of the
Albugo
–
Brassica
interaction.
Samridhi Mehta, Laxmi Awasthi, Rakhi Tomar et al.· Frontiers in Fungal Biology· 0 citations
Gymnema sylvestre (Gudmar) is an important medicinal plant recognized for its diverse bioactive compounds, including antimicrobial and immune-stimulatory properties, and for its association with beneficial endophytic microorganisms. However, the plant growth-promoting and biocontrol potential of its bacterial endophytes remains poorly understood. The present study aimed to isolate and characterize bacterial endophytes from different tissues of G. sylvestre and evaluate their PGP attributes and antagonistic activity against major soil-borne phytopathogens. A total of 30 bacterial endophytes were isolated from leaf (n = 14), stem (n = 9), and root (n = 7) tissues. Screening for PGP traits revealed that 36.7% of isolates produced indole-3-acetic acid (IAA) (>20 μg/mL), 56.7% produced siderophores, 16.7% solubilized phosphate, and 20.0% solubilized zinc. In addition, 30.0%, 23.3%, 16.7%, and 16.7% of isolates exhibited DNase activity, nitrate reduction, urease production, and citrate utilization, respectively. Extracellular enzyme production was also recorded, with isolates showing amylase (36.7%), protease (30.0%), cellulase (23.3%), and lipase (40.0%) activities. An antagonistic assay against soil-borne fungal pathogens using a dual culture assay showed inhibition of fungal growth in 5, 5, and 3 endophyte isolates against Sclerotium rolfsii, Rhizoctonia solani, and Fusarium oxysporum, respectively with maximum zone of inhibition up to 67%, 67% and 62%, respectively against each pathogen. Based on combined PGP and antagonistic performance, six elite isolates were selected for in-planta validation and molecular identification using 16S rDNA sequencing. In-planta evaluation in chickpea demonstrated significant improvements in seed germination, plant growth, and biomass compared with the uninoculated control. Bacillus cereus strain NIBSM_GdR7 produced the greatest increase in plant height, whereas Bacillus cabrialesii strain NIBSM_GdL7 yielded the highest fresh and dry biomass. Under pathogen challenge, seed biopriming of chickpea with selected endophytes reduced disease incidence caused by S. rolfsii, providing 68.7-87.8% protection, with the highest protection observed for Bacillus proteolyticus strain NIBSM_GdL2. These results indicate that G. sylvestre harbors bacterial endophytes with promising plant growth-promoting and antifungal properties, and that selected Bacillus isolates can in future serve as candidate bioinoculants for sustainable crop improvement and disease suppression.
A. Shrivastava, Lata Jain, Vinay Kumar et al.· Microbial Pathogenesis· 0 citations
Fall armyworm (FAW) is a major invasive pest causing significant damage to maize and other cereal crops, necessitating the development of sustainable management strategies. This study evaluated the toxicological and demographic effects of diet-incorporated silica nanoparticles (SiNPs) on FAW under laboratory conditions. SiNPs were incorporated into an artificial diet at concentrations of 100-500 ppm, along with an untreated control, and assessed for their effects on survival, development, reproduction, and population growth using age-stage, two-sex life table analysis. Larval mortality increased with concentration, reaching 85.77% at 500 ppm, with LC₅₀ and LC₉₀ values of 239.23 and 1438.61 ppm, respectively. SiNPs exposure significantly prolonged larval (18.60-24.59 days) and pupal (6.42-8.33 days) durations, while reducing pupal weight (male: 186.04-163.39 mg; female: 222.79-210.46 mg), adult longevity (8.62-7.26 days), female spawning (90.13% to 64.05%), and mating rate (92.81% to 66.13%), whereas mating frequency remained unaffected. Life table parameters showed declines in intrinsic rate of increase (0.158-0.064 day⁻¹), finite rate of increase (1.17-1.06 day⁻¹), and net reproductive rate (149.79-14.10 offspring per individual), along with increased mean generation time (31.67-41.16 days). These results demonstrate that dietary exposure to SiNPs adversely affects the growth, survival, and reproductive performance of FAW, leading to reduced population growth potential. Overall, the study provides clear evidence that SiNPs can suppress FAW populations under controlled conditions and highlights their potential as an eco-friendly component of integrated pest management, although further field-level validation is required.
Sourajit Dey, M. Jeer, G. Saw et al.· Scientific Reports· 1 citation
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