Biology subjects

Mahmud, N. U.

Publications and source records attributed to Mahmud, N. U..

4 recordsLinked to original sources

bioRxiv2023

Enhancing Rice Growth and Yield with Weed Endophytic Bacteria Alcaligenes faecalis and Metabacillus indicus Under Reduced Chemical Fertilization

Endophytic bacteria, recognized as eco-friendly biofertilizers, have demonstrated the potential to enhance crop growth and yield. While the plant growth-promoting effects of endophytic bacteria have been extensively studied, the impact of weed endophytes remains less explored. In this study, we aimed to isolate endophytic bacteria from native weeds and assess their plant growth-promoting abilities in rice under varying chemical fertilization. The evaluation encompassed measurements of mineral phosphate and potash solubilization, as well as indole-3-acetic acid (IAA) production activity by the selected isolates. Two promising strains, tentatively identified as Alcaligenes faecalis (BTCP01) from Eleusine indica (Goose grass) and Metabacillus indicus (BTDR03) from Cynodon dactylon (Bermuda grass) based on 16S rRNA gene phylogeny, exhibited noteworthy phosphate and potassium solubilization activity, respectively. BTCP01 demonstrated superior phosphate solubilizing activity, while BTDR03 exhibited the highest potassium (K) solubilizing activity. Both isolates synthesized IAA in the presence of L-tryptophan, with the detection of nifH and ipdC genes in their genomes. Application of isolates BTCP01 and BTDR03 through root dipping and spraying at the flowering stage significantly enhanced the agronomic performance of rice variety BRRI dhan29. Notably, combining both strains with 50% of recommended N, P, and K fertilizer doses led to a substantial increase in rice grain yields compared to control plants receiving 100% of recommended doses. Taken together, our results indicate that weed endophytic bacterial strains hold promise as biofertilizers, potentially reducing the dependency on chemical fertilizers by up to 50%, thereby fostering sustainable rice production.

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↗

bioRxiv2020

Oligomycins Inhibit Magnaporthe oryzae Triticum and suppress wheat blast disease

Oligomycins are macrolide antibiotics, produced by Streptomyces spp., show biological activities to several microorganisms like bacteria, fungi, nematodes and peronosporomycetes. Conidiogenesis, germination of conidia and formation of appressoria are crucial for a successful disease cycle and pathogenicity of the filamentous fungal phytopathogen. The goal of this research was to evaluate the effects of two oligomycins, oligomycin B and oligomycin F along with a commercial fungicide Nativo(R) 75WG on hyphal growth, conidiogenesis, conidia germination, appressoria formation, and disease development of a worrisome wheat blast fungus, Magnaporthe oryzae Triticum (MoT) pathotype. Both oligomycins suppressed the growth of MoT mycelia depending on the dose. Between the two natural products, oligomycin F displayed the maximum inhibition of MoT hyphal growth accompanied by oligomycin B with minimum inhibitory concentrations (MICs) of 0.005 and 0.05 g/disk, respectively. The application of the compounds also completely halted the conidia formation in the MoT mycelia in agar medium. A further bioassay showed that these compounds significantly inhibited MoT conidia germination and induced lysis; if germinated, induced abnormal germ tube and suppressed appressoria formation. Interestingly, the application of these macrolides significantly inhibited wheat blast disease on detached leaves of wheat. This is a first report on the inhibition of mycelial growth, process of conidia formation, germination of conidia, morphological changes in germinated conidia, and suppression of blast disease of wheat by oligomycins from Streptomyces spp. A further study is needed to evaluate the mode of action and field trials of these natural compounds to consider them as biopesticides for controlling this devastating wheat killer.

microbiology↗

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↗