Institutional Publications

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Genotype-independent Agrobacterium rhizogenes-mediated root transformation of chickpea: a rapid and efficient method for reverse genetics studies
(BioMed Central Ltd, 2018) Aggarwal, Pooja Rani; Nag, Papri; Choudhary, Pooja; Chakraborty, Niranjan; Chakraborty, Subhra
Background: Chickpea (Cicer arietinum L.), an important legume crop is one of the major source of dietary protein. Developing an efcient and reproducible transformation method is imperative to expedite functional genomics studies in this crop. Here, we present an optimized and detailed procedure for Agrobacterium rhizogenes-mediated root transformation of chickpea. Results: Transformation positive roots were obtained on selection medium after two weeks of A. rhizogenes inoculation. Expression of green fuorescent protein further confrmed the success of transformation. We demonstrate that our method adequately transforms chickpea roots at early developmental stage with high efciency. In addition, root transformation was found to be genotype-independent and the efcacy of our protocol was highest in two (Annigiri and JG-62) of the seven tested chickpea genotypes. Next, we present the functional analysis of chickpea hairy roots by expressing Arabidopsis TRANSPARENT TESTA 2 (AtTT2) gene involved in proanthocyanidins biosynthesis. Overexpression of AtTT2 enhanced the level of proanthocyanidins in hairy roots that led to the decreased colonization of fungal pathogen, Fusarium oxysporum. Furthermore, the induction of transgenic roots does not afect functional studies involving infection of roots by fungal pathogen. Conclusions: Transgenic roots expressing genes of interest will be useful in downstream functional characterization using reverse genetics studies. It requires 1 day to perform the root transformation protocol described in this study and the roots expressing transgene can be maintained for 3–4 weeks, providing sufcient time for further functional studies. Overall, the current methodology will greatly facilitate the functional genomics analyses of candidate genes in root-rhizosphere interaction in this recalcitrant but economically important legume crop.
Interplay of neuronal and non-neuronal genes regulates intestinal DAF-16-mediated immune response during Fusarium infection of Caenorhabditis elegans
(Nature Publishing Group, 2017) Nag, Papri; Aggarwal, Pooja Rani; Ghosh, Sudip; Narula, Kanika; Tayal, Rajul; Maheshwari, Nidhi; Chakraborty, Niranjan; Chakraborty, Subhra
Although precisely controlled innate immune response is governed by conserved cellular events in phylogenetically diverse hosts, the underlying molecular mechanisms by which this process is regulated against a multi-host pathogen remain unknown. Fusarium oxysporum is a model multi-host pathogen, known to be associated with neuronal stress in humans and vascular wilt in plants. The interaction between innate immune and neuronal pathways is the basis of many diverse biological responses. How these processes are coordinated in response to fungal disease is not well understood. Here, we show that F. oxysporum f. sp. ciceri causes neuronal stress and intestinal disintegration, ultimately leading to the death of Caenorhabditis elegans. To explore the regulatory framework of Fusarium-associated disease, we analysed the gene expression during infection, integrated temporal gene expression, and network analysis with genetic inactivation data in Caenorhabditis elegans. We identified 1024 genes showing significant changes in expression (corrected P-values <0.05) in response to Fusarium infection. Co-expression network analysis of our data identified prognostic genes related to disease progression. These genes were dynamically expressed in various neuronal and non-neuronal tissues exhibiting diverse biological functions, including cellular homeostasis, organ patterning, stress response, and lipid metabolism. The RNA-seq analysis further identified shared and unique signalling pathways regulated by DAF-16/FOXO and SIR-2.1 linking neuronal stress, which facilitates negative regulation of intestinal innate immunity. Genetic analysis revealed that GCY-5 in ASE functions upstream of DAF-16, whereas ASI-specific SRD-1 regulates behavioural immunity. Overall, our results indicate that a ubiquitous response occurs during Fusarium infection mediated by highly conserved regulatory components and pathways, which can be exploited further for the identification of disease-responsive genes conserved among animals and plants. Finally, this study provided a novel insight into cross-species immune signalling and may facilitate the discovery of cellular therapeutic targets for Fusarium-associated disease.
Impact of concurrent drought stress and pathogen infection on plants
(Springer, 2015) Pandey, Prachi; Sinha, Ranjita; Mysore, Kirankumar S.; Senthil-Kumar, Muthappa
Concurrent abiotic and biotic stress situations greatly limit the crop productivity. The global climate change is predicted to bring forth the frequent incidences of concurrent stresses, predominantly drought and pathogen infections. Thus, understanding the impact of drought on plant–pathogen interaction is important. In this chapter, we review the recent studies that focus on the effect of concurrent drought and pathogen infection on plants. These studies indicate that concurrent stress conditions lead to the activation of unique combat pathways that are otherwise not elicited under independent stresses. Plant responses, thus, seem to be adaptively tailored for combating the combined stresses. Here, we focus on the impact of drought stress on plant–pathogen relations and highlight the different ways by which plant–pathogen interactions are modulated at physiological and molecular level. Various studies reviewed in this chapter show that the stress combinations should be considered as a “unique stress” and a better understanding of plant responses to these conditions is needed. Therefore, we propose that further efforts should be directed to identify the potential pathways conferring concurrent stress tolerance.

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