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Author: search.filters.author.Kumar, Deepak

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    Seed endophytic bacterium Lysinibacillus sp. (ZM1) from maize (Zea mays L.) shapes its root architecture through modulation of auxin biosynthesis and nitrogen metabolism
    (Elsevier B.V., 2024) Pal, Gaurav; Saxena, Samiksha; Kumar, Kanchan; Verma, Anand; Kumar, Deepak; Shukla, Pooja; Pandey, Ashutosh; White, James; Verma, Satish K.
    Seed endophytic bacteria have been shown to promote the growth and development of numerous plants. However, the underlying mechanism still needs to be better understood. The present study aims to investigate the role of a seed endophytic bacterium Lysinibacillus sp. (ZM1) in promoting plant growth and shaping the root architecture of maize seedlings. The study explores how bacteria-mediated auxin biosynthesis and nitrogen metabolism affect plant growth promotion and shape the root architecture of maize seedlings. The results demonstrate that ZM1 inoculation significantly enhances root length, root biomass, and the number of seminal roots in maize seedlings. Additionally, the treated seedlings exhibit increased shoot biomass and higher levels of photosynthetic pigments. Confocal laser scanning microscopy (CLSM) analysis revealed extensive colonization of ZM1 on root hairs, as well as in the cortical and stellar regions of the root. Furthermore, LC-MS analysis demonstrated elevated auxin content in the roots of the ZM1 treated maize seedlings compared to the uninoculated control. Inoculation with ZM1 significantly increased the levels of endogenous ammonium content, GS, and GOGAT enzyme activities in the roots of treated maize seedlings compared to the control, indicating enhanced nitrogen metabolism. Furthermore, inoculation of bacteria under nitrogen-deficient conditions enhanced plant growth, as evidenced by increased root shoot length, fresh and dry weights, average number of seminal roots, and content of photosynthetic pigments. Transcript analysis indicated upregulation of auxin biosynthetic genes, along with genes involved in nitrogen metabolism at different time points in roots of ZM1-treated maize seedlings. Collectively, our findings highlight the positive impact of Lysinibacillus sp. ZM1 inoculation on maize seeds by improving root architecture through modulation of auxin biosynthesis and affecting various nitrogen metabolism related parameters. These findings provide valuable insights into the potential utilization of seed endophytic bacteria as biofertilizers to enhance plant growth and yield in nutrient deficient soils.
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    Seed endophytic bacterium Bacillus velezensis and its lipopeptides acts as elicitors of defense responses against Fusarium verticillioides in maize seedlings
    (Springer Nature Publishing AG, 2023) Pal, Gaurav; Saxena, Samiksha; Kumar, Kanchan; Verma, Anand; Kumar, Deepak; Shukla, Pooja; Pandey, Ashutosh; Verma, Satish K.
    Purpose: The potential of endophytic bacteria to improve plant health has been well-established. In maize plants, studies have reported the antagonistic activity of endophytic bacteria against various kinds of phytopathogenic strains; however, the effect of lipopeptide inoculation on germinated seedlings and its underlying defense responses remain unexplored. In this study, we examined the effects of seed endophytic bacterium Bacillus velezensis and its lipopeptides in improving plant defense against Fusarium verticillioides in maize seedlings. Methods: In vitro germinated maize seedlings were treated with lipopeptides extracted from the B. velezensis, followed by inoculation with the phytopathogen Fusarium verticillioides. The lipopeptides were characterized using MALDI-TOF analysis and their effects on fungal colonization and defense gene expression were investigated. Polyphenol content was checked in the bacterium-ZMW8 as well as ZMW8 and Fusarium-inoculated seedlings through UHPLC. Results: Lipopeptide treatment to the maize seedling’s roots resulted in enhanced protection from the fungus with significant improvement in all the growth parameters measured. Antifungal lipopeptides were identified as bacillomycin D and fengycin. Confocal microscopy images revealed the heavy colonization of fungus on the seed and root surface of non-lipopeptide-treated seedlings. Gene expression analysis revealed upregulation of various defense response genes including ZmPR-1, ZmPR-4, ZmSOD-2, ZmLOX, ZmPDF1.2, and ZmERF in the roots of bacteria and lipopeptides-treated maize seedlings. Targeted metabolite analysis through UHPLC revealed the accumulation of antifungal polyphenols including p-coumaric acid, kaempferol, dihydrokaempferol (DHK), and dihydroquercetin (DHQ). Conclusions: The study highlights the potential of bacterial lipopeptides as elicitors of defense responses in maize seedlings against Fusarium infection.