Biology subjects

Gupta, D. R.

Publications and source records attributed to Gupta, D. R..

4 recordsLinked to original sources

bioRxiv2026

First occurrence of Corynespora cassiicola infecting chia plant in Bangladesh and its sensitivity to selected fungicides

Chia (Salvia hispanica L.) is an emerging crop in Bangladesh valued for its medicinal properties and economic significance. In March 2024, target spot-like symptoms were observed in an experimental chia field (24.75{degrees} N, 90.50{degrees} E) at Bangladesh Agricultural University in Mymensingh, Bangladesh with disease incidence ranging from 23% to 47% across approximately 0.25 ha. Initially appearing as brick-red spots, these symptoms developed into target-shaped concentric rings, affecting leaves, stems, and inflorescences. A total of 24 fungal isolates were recovered from infected tissue; two representative isolates (BGECh-3 and BGECh-4) were randomly selected for details characterization. Pathogen identity was established through morphological traits, multilocus phylogenetic analysis of internal transcribed spacer (ITS) and elongation factor 1-alpha (EF-1) genes sequence, and pathogenicity confirmation through Kochs postulates, collectively identifying the causal agent as Corynespora cassiicola. The isolates demonstrated a broad host range, successfully infecting brinjal, chili, bottle gourd, country bean, tomato, and soybean. In vitro fungicide sensitivity assays with seven commercial fungicides showed that both isolates were highly sensitive to Goldzim (50% carbendazim), which completely inhibited mycelial growth at 10 {micro}g mL-{superscript 1}. Conza (10% Hexaconazole) and Amister top (18.2% azoxystrobin + 11.4% difenoconazole) reduced growth by up to 85% and 67%, respectively at equal concentration. Other fungicides showed comparatively lower efficacy even at higher concentrations. This study represents the first report of target spot disease of chia caused by C. cassiicola in Bangladesh and provides insights for effective disease management strategies.

molecular biology↗

bioRxiv2026

3-Methylpentanoic acid from Bacillus safensis suppresses wheat blast disease by targeting UDP-glucose 4-epimerase

Wheat blast, caused by Magnaporthe oryzae Triticum (MoT), is a devastating disease threatening global food security. Current reliance on chemical fungicides is unreliable due to the development of resistant MoT populations, highlighting the need for safe and eco-friendly alternatives. Naturally occurring volatile organic compounds (VOCs) possess potent antifungal potential thereby inhibiting phytopathogen. In this study, we investigated the fungicidal potential of 3-methylpentanoic acid (3-MP), a VOC produced by Bacillus safensis and also found in snake-fruit aroma, on MoT pathogen. In vitro assays revealed dose-dependent inhibition of MoT mycelial growth, conidiogenesis, conidial germination, and appressorium formation, with complete suppression achieved at 100-125 {micro}M. Detached leaf, seedling, and spike assays demonstrated robust preventive and curative protection, highlighting translational potential under field conditions. Mechanistic investigations showed that 3-MP compromises membrane integrity, as confirmed by fluorescein diacetate staining, and targets UDP-glucose 4-epimerase (UGE), a key enzyme required for galactose metabolism and cell wall integrity in fungi. Molecular dynamics simulations revealed stable binding of 3-MP within the NAD-associated Rossmann fold of UGE, sterically blocking substrate access and perturbing NAD orientation. RT-PCR gene expression analysis corroborated this model, showing early induction followed by repression of UGE expression, consistent with collapse of UDP-glucose metabolism and impaired cell wall biosynthesis. This study for the first time identified 3-MP as a natural inhibitor of UGE and provided new insight into the antifungal mechanism of the compound, highlighting its potential for integrated wheat blast management. ImportanceWheat blast, caused by Magnaporthe oryzae Triticum (MoT), poses a catastrophic threat to global food security, particularly in South America, Africa, and South Asia. With MoT rapidly developing resistance to conventional chemical fungicides, there is an urgent need for sustainable, eco-friendly alternatives. Our study identifies 3-methylpentanoic acid (3-MP), a volatile organic compound produced by Bacillus safensis, as a potent antifungal agent against MoT. We demonstrate that 3-MP inhibits multiple life stages of the pathogen, including mycelial growth, conidiation, and appressorium formation. Furthermore, we provide molecular insights through molecular docking and MD simulations, identifying UDP-glucose 4-epimerase as a likely target of 3-MP. By revealing a dual-action (preventive and curative) natural compound and its potential mechanism, this work offers a promising blueprint for developing bio-based fungicides to combat devastating plant diseases while reducing the environmental footprint of agriculture.

microbiology↗

bioRxiv2022

A pandemic clonal lineage of the wheat blast fungus

Wheat, the most important food crop, is threatened by a blast disease pandemic. Here, we show that a clonal lineage of the wheat blast fungus recently spread to Asia and Africa following two independent introductions from South America. Through a combination of genome analyses and laboratory experiments, we show that the decade-old blast pandemic lineage can be controlled by the Rmg8 disease resistance gene and is sensitive to strobilurin fungicides. However, we also highlight the potential of the pandemic clone to evolve fungicide-insensitive variants and sexually recombine with African lineages. This underscores the urgent need for genomic surveillance to track and mitigate the spread of wheat blast outside of South America, and to guide pre-emptive wheat breeding for blast resistance.

evolutionary biology↗

bioRxiv2018

The MoT3 assay does not distinguish between Magnaporthe oryzae wheat and rice blast isolates from Bangladesh

The blast fungus Magnaporthe oryzae is comprised of lineages that exhibit varying degrees of specificity on about 50 grass hosts, including rice, wheat and barley. Reliable diagnostic tools are essential given that the pathogen has a propensity to jump to new hosts and spread to new geographic regions. Of particular concern is wheat blast, which has suddenly appeared in Bangladesh in 2016 before spreading to neighboring India. In these Asian countries, wheat blast strains are now co-occurring with the destructive rice blast pathogen raising the possibility of genetic exchange between these destructive pathogens. We assessed the recently described MoT3 diagnostic assay and found that it did not distinguish between wheat and rice blast isolates from Bangladesh. The assay is based on primers matching the WB12 sequence corresponding to a fragment of the M. oryzae MGG_02337 gene annotated as a short chain dehydrogenase. These primers could not reliably distinguish between wheat and rice blast isolates from Bangladesh based on DNA amplification experiments performed in separate laboratories in Bangladesh and in the UK. In addition, comparative genomics of the WB12 sequence revealed a complex underlying genetic structure with related sequences across M. oryzae strains and in both rice and wheat blast isolates. We, therefore, caution against the indiscriminate use of this assay to identify wheat blast.

plant biology↗