Publications of NIPGR Scientists

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Start date: 2020Subject: search.filters.subject.Pseudomonas syringae

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Now showing 1 - 7 of 7
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    CBL1/9-CIPK6 complex negatively regulates respiratory burst oxidase homolog D in Arabidopsis thaliana
    (John Wiley & Sons, 2026) Vishwakarma, Niraj Kumar; Yadav, Shalini; Sardar, Atish; Choudhary, Megha; Chattopadhyay, Debasis
    Plant innate immune response is a well-balanced process with positive and negative regulations for the plants to survive. Calcium signaling is essential for pathogen-associated molecular pattern (PAMP)-driven respiratory burst oxidase homolog D (RBOHD)-mediated reactive oxygen species (ROS) burst. We show that calcium sensors calcineurin B like protein 1 (CBL1) and CBL9 and their interacting protein kinase CIPK6 negatively regulate RBOHD activity and immune response in Arabidopsis thaliana. Arabidopsis mutant cbl1cbl9, like cipk6, exhibited enhanced resistance and ROS production when infected with the bacterial pathogen Pseudomonas syringae pv. tomato (Pst). CBL1 and CBL9 enhanced kinase activity of CIPK6. CBL1/9-CIPK6 module interacts with RBOHD at the plasma membrane. CIPK6 along with CBL1 reduces RBOHD activity in planta. CIPK6 phosphorylates the N-terminal cytoplasmic domain of RBOHD at a non-conserved (S33) and a conserved (S39) serine residue. While S39 phosphorylation increased RBOHD activity, S33 phosphorylation drastically reduced it and superseded the effect of S39 phosphorylation. We propose a model that CIPK6 phosphorylates RBOHD at S33 to suppress its activity to balance ROS generation in post-PTI situation in Arabidopsis. Our study reports a direct mechanism of negative regulation of ROS production and plant immune response by a calcium-signaling module in Arabidopsis thaliana.
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    Drought attenuates plant defence against bacterial pathogens by suppressing the expression of CBP60g/SARD1 during combined stress
    (John Wiley & Sons, 2022) Choudhary, Aanchal; Senthil-Kumar, Muthappa
    In nature, plants are frequently exposed to drought and bacterial pathogens simultaneously. However, information on how the drought and defence pathways interact and orchestrate global transcriptional regulation is limited. Here, we show that moderate drought stress enhances the susceptibility of Arabidopsis thaliana to Pseudomonas syringae pv. tomato DC3000. Using transcriptome meta-analysis, we found that drought and bacterial stress antagonistically modulate a large set of genes predominantly involved in salicylic acid (SA) and abscisic acid (ABA) signalling networks. We identified that the levels of SA and ABA are dynamically regulated during the course of stress. Importantly, under combined stress, drought through the ABA pathway downregulates the induction of CALMODULIN-BINDING PROTEIN 60g (CBP60g) and SYSTEMIC ACQUIRED RESISTANCE DEFICIENT 1 (SARD1), two transcription factors crucial for SA production upon bacterial infection. We also identified an important role of NPR1-LIKE PROTEIN 3 and 4 (NPR3/4) transcriptional repressors in the drought-mediated negative regulation of CBP60g/SARD1 expression. Using a genetic approach, we show that CBP60g/SARD1 expression is the key determinant of plant defence against bacterial pathogens under combined stress. Thus, these transcription factors act as critical nodes for the crosstalk between drought and bacterial stress signalling under combined stress in plants.
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    Investigation of the novel transcriptional changes under combined drought and bacterial stress underpins the role of AtMYB96 in imparting tolerance
    (Springer Nature Publishing AG, 2021) Choudhary, Aanchal; Senthil-Kumar, Muthappa
    The physiological and molecular responses instigated to combat drought and bacterial pathogens often work antagonistically and, in most cases, the impact of combined stress is more detrimental to plant growth. Interestingly, plants exposed to this stress combination show a novel transcriptome fingerprint with a significant set of genes that are uniquely altered under combined stress. Despite this being reported in several transcriptomic datasets, our molecular understanding of these combined stress-specific genes and pathways is still in its nascent stages. These unique genes and the dedicated regulatory pathways are important for understanding the molecular aspects of signaling responses under combined stress. In this study, a previously available microarray dataset was extensively reanalysed to identify the novel genes and pathways specifically altered under combined stress. Using a combination of bioinformatic and data-guided approaches, we identified major biological pathways, transcription factor (TF) network and novel motifs potentially involved in the combined stress-specific responses. The candidate gene analysis using gene expression and mutant analysis identified AtMYB96 as an important TF involved in combined stress response. Taken together, our analysis pinpoints many novel genes that can be used for understanding the molecular mechanism of how plants deal with the combination of drought and bacterial pathogen.
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    An efficient, high-throughput method for the simultaneous exposure of drought stress and bacterial infection in plants
    (John Wiley & Sons, 2020) Choudhary, Aanchal; Senthil-Kumar, Muthappa
    PREMISE: We developed a systematic protocol for the easy, high-throughput, qualitative, and quantitative assessment of the patho-morphological, physiological, and molecular responses of Arabidopsis thaliana plants simultaneously subjected to drought and bacterial infection. This approach will assist studies elucidating plant adaptation strategies to combat combined stresses. METHODS AND RESULTS: Plants were grown in small screw-capped containers, individual pots, or pot strips. Watering was withheld from 30-day-old plants, which were subsequently infected with Pseudomonas syringae pv. tomato DC3000 using a dip inoculation. The natural development of both drought and bacterial infection was successfully and rapidly replicated in large numbers of plants, which is difficult to achieve with existing protocols. CONCLUSIONS: Our protocol offers a simple, low-cost, high-throughput strategy for the rapid and easy bacterial infection of large numbers of plants. It can be used in large-scale mutant and ecotype screenings under combined stresses and for other foliar pathogens in different plant species.
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    ath-miR164c influences plant responses to the combined stress of drought and bacterial infection by regulating proline metabolism
    (Elsevier B.V., 2020) Gupta, Aarti; Patil, Mahesh; Qamar, Aarzoo; Senthil-Kumar, Muthappa
    Plants under combined stresses exhibit a prominent shift in molecular responses compared with plants exposed to the same stresses independently. Profiling responses to individual and combined stressors at the gene expression level have identified several genes with intersecting responses to these stressors. However, the upstream regulators at the intersection of plant responses to individual and combined stresses are not known. Here, using the transcriptome of Arabidopsis thaliana under individual and combined drought and Pseudomonas syringae infection, we identified several genes whose expression overlaps between individual and combined stresses. To study the key regulator of such an overlapping gene, we predicted that the expression of 1-Pyrroline-5-carboxylate synthase 1 (AtP5CS1) is regulated by ath-miR164c at post-transcriptional level. Our results from the stem-loop RT-PCR based expression analysis revealed significant downregulation of ath-miR164c in response to P. syringae infection under both well-irrigated (pathogen only) and drought stress (combined stress) conditions. Furthermore, an Arabidopsis loss-of-function mutant of the miRNA ath-miR164c exhibited resistance to pathogen infection under combined stress, unlike the wild-type plants, implicating the role of ath-miR164c in regulating plant immunity. AtP5CS1 gene expression and proline accumulation were enhanced in the ath-miR164c mutant plants relative to the wild-type plants, demonstrating that ath-miR164c regulates AtP5CS1 of the proline biosynthesis pathway, which was also validated by 5’RLM-RACE results. This miRNA-mediated modulation of AtP5CS1 gene expression under combined stress fills crucial gaps in identifying the key convergent players in the current understanding of plant stress responses.
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    Using different forms of nitrogen to study hypersensitive response elicited by avirulent Pseudomonas syringae
    (Springer Nature Publishing AG, 2020) Singh, Namrata; Singh, Pooja; Pathak, Pradeep Kumar; Gupta, Kapuganti Jagadis
    Nitrate, ammonium, or a combination of both is the form of N available for nitrogen assimilation from soil by the plants. Nitrogen is an important and integral part of amino acids, nucleotides, and defense molecules. Hence it is very important to study the role of nitrate and ammonium nutrition in plant defense via hypersensitive response (HR). Shifting plants from ammonium nitrate Hoagland solution to nitrate Hoagland nutrition slightly enhances root length and leaf area. HR phenotype is different in nitrate and ammonium grown plants when challenged with avirulent Pseudomonas syringae DC3000 avrRpm1. HR is also associated with increased production of reactive oxygen species (ROS) and nitric oxide (NO). Hence to understand HR development it is essential to measure HR lesions, cell death, ROS, NO, and bacterial growth. Here we provide a stepwise protocol of various parameters to study HR in Arabidopsis in response to nitrate and ammonium nutrition.
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    Using foldscope to monitor superoxide production and cell death during pathogen infection in arabidopsis under different nitrogen regimes
    (Springer Nature Publishing AG, 2020) Arora, Reena; Singh, Pooja; Kumari, Aprajita; Pathak, Pradeep Kumar; Gupta, Kapuganti Jagadis
    Nitrogen nutrition plays a role in plant growth development and resistance against biotic and abiotic stress. During pathogen infection various signal molecules such as reactive oxygen species, calcium, reactive nitrogen species, salicylic acid, and ethylene plays an important role. The form of nitrogen nutrition such as nitrate or ammonium plays a role in production of these molecules. Under nitrate nutrition NO is predominant. The produced NO plays a role in reacting with superoxide to generate peroxynitrite to induce cell death during hypersensitive response elicited by avirulent pathogens. Excess of ROS is also detrimental to plants and NO plays a role in regulating ROS. Hence it is important to observe superoxide production during infection. By using an avirulent Pseudomonas syringae and Arabidopsis differential N nutrition we show superoxide production in leaves using a paper microscope called Foldscope, which can be applied as a simple microscope to observe objects. The data also compared with root system infected with pathogenic Fusarium oxysporum. Taken together here we show that Foldscope is a cost-effective and powerful technique to visualize superoxide and cell death in plants during infection.