Publications of NIPGR Scientists

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Author: search.filters.author.Jha, GopaljeeSubject: search.filters.subject.T3SS

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    A prophage tail-like protein facilitates the endophytic growth of Burkholderia gladioli and mounting immunity in tomato
    (John Wiley & Sons, 2023) Chandan, Ravindra Kumar; Kumar, Rahul; Kabyashree, Kristi; Yadav, Sunil Kumar; Roy, Mandira; Swain, Durga Madhab; Jha, Gopaljee
    A prophage tail-like protein (Bg_9562) of Burkholderia gladioli strain NGJ1 possesses broad-spectrum antifungal activity, and it is required for the bacterial ability to forage over fungi. Here, we analyzed whether heterologous overexpression of Bg_9562 or exogenous treatment with purified protein can impart disease tolerance in tomato. The physiological relevance of Bg_9562 during endophytic growth of NGJ1 was also investigated. Bg_9562 overexpressing lines demonstrate fungal and bacterial disease tolerance. They exhibit enhanced expression of defense genes and activation of mitogen-activated protein kinases. Treatment with Bg_9562 protein induces defense responses and imparts immunity in wild-type tomato. The defense-inducing ability lies within 18-51 aa region of Bg_9562 and is due to sequence homology with the bacterial flagellin epitope. Interaction studies suggest that Bg_9562 is perceived by FLAGELLIN-SENSING 2 homologs in tomato. The silencing of SlSERK3s (BAK1 homologs) prevents Bg_9562-triggered immunity. Moreover, type III secretion system-dependent translocation of Bg_9562 into host apoplast is important for elicitation of immune responses during colonization of NGJ1. Our study emphasizes that Bg_9562 is important for the endophytic growth of B. gladioli, while the plant perceives it as an indirect indicator of the presence of bacteria to mount immune responses. The findings have practical implications for controlling plant diseases.
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    Calcium regulates the mycophagous ability of Burkholderia gladioli strain NGJ1 in a type III secretion system-dependent manner
    (BioMed Central Ltd, 2020) Yadav, Sunil Kumar; Das, Joyati; Kumar, Rahul; Jha, Gopaljee
    Background: A rice associated bacterium Burkholderia gladioli strain NGJ1 demonstrates mycophagy, a phenomenon wherein bacteria feed on fungi. Previously, we have reported that NGJ1 utilizes type III secretion system (T3SS) to deliver a prophage tail-like protein (Bg_9562) into fungal cells to establish mycophagy. Results: In this study, we report that calcium ion concentration influences the mycophagous ability of NGJ1 on Rhizoctonia solani, an important fungal pathogen. The calcium limiting condition promotes mycophagy while high calcium environment prevents it. The expression of various T3SS apparatus encoding genes of NGJ1 was induced and secretion of several potential T3SS effector proteins (including Bg_9562) into extracellular milieu was triggered under calcium limiting condition. Using LC-MS/MS proteome analysis, we identified several calcium regulated T3SS effector proteins of NGJ1. The expression of genes encoding some of these effector proteins was upregulated during mycophagous interaction of NGJ1 with R. solani. Further, mutation of one of these genes (endo-β-1, 3- glucanase) rendered the mutant NGJ1 bacterium defective in mycophagy while complementation with full length copy of the gene restored its mycophagous activity. Conclusion: Our study provides evidence that low calcium environment triggers secretion of various T3SS effectors proteins into the extracellular milieu and suggests the importance of cocktail of these proteins in promoting mycophagy