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    Proteomic signatures uncover phenotypic plasticity of susceptible and resistant genotypes by wall remodelers in rice blast
    (John Wiley & Sons, 2024) Sinha, Arunima; Narula, Kanika; Bhola, Latika; Sengupta, Atreyee; Choudhary, Pooja; Nalwa, Pragya; Kumar, Mohit; Elagamey, Eman; Chakraborty, Niranjan; Chakraborty, Subhra
    Molecular communication between macromolecules dictates extracellular matrix (ECM) dynamics during pathogen recognition and disease development. Extensive research has shed light on how plant immune components are activated, regulated and function in response to pathogen attack. However, two key questions remain largely unresolved: (i) how does ECM dynamics govern susceptibility and disease resistance, (ii) what are the components that underpin these phenomena? Rice blast, caused by Magnaporthe oryzae adversely affects rice productivity. To understand ECM regulated genotype-phenotype plasticity in blast disease, we temporally profiled two contrasting rice genotypes in disease and immune state. Morpho-histological, biochemical and electron microscopy analyses revealed that increased necrotic lesions accompanied by electrolyte leakage governs disease state. Wall carbohydrate quantification showed changes in pectin level was more significant in blast susceptible compared to blast resistant cultivar. Temporally resolved quantitative disease- and immune-responsive ECM proteomes identified 308 and 334 proteins, respectively involved in wall remodelling and integrity, signalling and disease/immune response. Pairwise comparisons between time and treatment, messenger ribonucleic acid expression, diseasome and immunome networks revealed novel blast-related functional modules. Data demonstrated accumulation of α-galactosidase and phosphatase were associated with disease state, while reactive oxygen species, induction of Lysin motif proteins, CAZymes and extracellular Ca-receptor protein govern immune state.
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    Magnaporthe oryzae MoNdt80 is a transcriptional regulator of GlcNAc catabolic pathway involved in pathogenesis
    (Elsevier B.V., 2020) Bhatt, Dharmendra Nath; Ansari, Sekhu; Kumar, Anil; Ghosh, Sumit; Narula, Alka; Datta, Asis
    Availability and efficient utilization of host-derived nutrients by pathogens decide the fate of host-pathogen interaction. In Magnaporthe oryzae, N-acetylglucosamine (GlcNAc) catabolic pathway was found essential for successful host colonization and pathogenicity. GlcNAc catabolic enzymes hexokinase, GlcNAc-6-phosphate deacetylase (MoDac) and GlcN-6-phosphate deaminase (MoDeam) are encoded in a genomic cluster in M. oryzae and several phytopathogenic fungi. However, transcriptional regulation of GlcNAc catabolic pathway was not understood. We identified a conserved Ndt80/PhoG-like transcriptional regulator as a part of the GlcNAc catabolic gene cluster in M. oryzae and other fungi. We found that MoNdt80 is essential for GlcNAc utilization and pathogenicity of M. oryzae. Unlike WT, ΔMoNdt80 failed to induce transcription of GlcNAc catabolic pathway genes in response to GlcNAc. MoNdt80 could bind to a specific cis-acting consensus sequence GNCRCAAA[AT], present in the promoter of MoDac, MoDeam and β-hexosaminidase (MoHex). Further, comparative RNA-sequencing analysis using WT and ΔMoNdt80 revealed a large set of GlcNAc responsive genes that are under the transcriptional control of MoNdt80. These genes encoded GlcNAc catabolic enzymes, transporters and cell wall degrading enzymes which are required for hyphal growth expansion during host colonization. Overall, these results suggest MoNdt80 mediated transcriptional regulation of GlcNAc catabolic pathway is essential for successful host colonization and pathogenesis.
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    Comparative nuclear proteomics analysis provides insight into the mechanism of signaling and immune response to blast disease caused by Magnoporthe oryzae in rice
    (John Wiley & Sons, 2019) Narula, Kanika; Choudhary, Pooja; Ghosh, Sudip; Elagamey, Eman; Chakraborty, Niranjan; Chakraborty, Subhra
    Modulation of plant immune system by extrinsic/intrinsic factors and host-specific determinants fine-tunes cellular components involving multiple organelles, particularly nucleus to mount resistance against pathogen attack. Rice blast, caused by hemibiotrophic fungus Magnaporthe oryzae, is one of the most devastating diseases that adversely affect rice productivity. However, the role of nuclear proteins and their regulation in response to M. oryzae remains unknown. Here, we elucidate the nucleus-associated immune pathways in blast resistant rice genotype. Temporal analysis of nuclear proteome was carried out using 2-DE coupled MS/MS analysis. A total of 140 immune responsive proteins (IRPs) were identified associated with nuclear reorganization, cell division, energy production/deprivation, signaling and gene regulation. We interrogated the proteome data using correlation network analysis that identified significant functional modules pointing towards immune related coinciding processes through a common mechanism of remodelling and homeostasis. Novel clues regarding blast resistance include nucleus associated redox homeostasis and glycolytic enzyme mediated chromatin organization which manipulates cell division and immunity. Taken together, our study provides evidence that coordination of nuclear function and reprogramming of host translational machinery regulate resistance mechanism against blast disease.
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    Magnaporthe oryzae aminosugar metabolism is essential for successful host colonization
    (John Wiley & Sons, 2016) Kumar, Anil; Ghosh, Sumit; Bhatt, Dharmendra Nath; Narula, Alka; Datta, Asis
    Pathogens encounter and metabolize a range of host-derived metabolites while proliferating inside the host. Our understanding of these metabolites and their metabolic processes has remained largely incomplete. We investigated the role of the Magnaporthe oryzae N-acetylglucosamine (GlcNAc) catabolic pathway during rice infection. The catabolic pathway is composed of a GlcNAc transporter (MoNgt1), hexokinase(s), a GlcNAc-6-phosphate deacetylase (MoDac) and a GlcN-6-phosphate deaminase (MoDeam). A detailed characterization of the Δmongt1, Δmodac and Δmodeam null mutants revealed that a defect in GlcNAc catabolism impairs the pathogenicity of M. oryzae. These mutants showed severely reduced virulence in susceptible rice cultivar due to their inability to neutralize host-derived reactive oxygen species and their failure to develop invasive hyphal growth within the host tissue. Interestingly, during oxidative stress, M. oryzae proliferated efficiently in GlcNAc-containing media compared to other sugars, and the expression of fungal antioxidant genes was up-regulated following GlcNAc treatment. However, GlcNAc inhibited the growth of the Δmodac and Δmodeam mutants, and this growth inhibition was enhanced during oxidative stress. These results suggest that GlcNAc helps fungus to overcome oxidative stress inside its host, perhaps by activating an anti-oxidant defence. In the absence of a functional catabolic pathway, GlcNAc becomes toxic to the cells.
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    Involvement of mitogen activated protein kinase kinase 6 in UV induced transcripts accumulation of genes in phytoalexin biosynthesis in rice
    (Springer, 2013) Wankhede, Dhammaprakash Pandhari; Kumar, Kundan; Singh, Pallavi; Sinha, Alok Krishna
    BACKGROUND: Ultra violet radiation leads to accumulation of phytoalexins (PA) in rice (Oryza sativa) which are typically accumulated when the plants are infected with rice blast pathogen Magnaporthe oryzae. Although extensive works have been done in elucidating phytoalexin biosynthesis, UV stress signal transduction leading to accumulations of rice phytoalexin is largely unknown.