Research Projects

Chickpea (Cicer arietinum L.) is a rich source of dietary protein and is important in providing nutritional balance. India, despite being, the largest producer of chickpea in the world, is still importing several million tons yearly to meet the growing demand. This is because its yields are challenged by a wide array of pathogens. Indian chickpea production is, largely, affected by Fusarium and Ascochyta infections with Botrytis being added to the list recently. However, the report about chickpea yield loss due to B. cinerea infection has pressed an alarming bell as no natural resistance genes against B. cinerea are yet known in chickpea. This necessitates the intervention of genetic engineering approaches for devising effective control strategies focussed on improving chickpea resilience against B. cinerea infection. Degradation of plant cell wall by fungal pathogens marks a crucial step towards successful infection and colonization. Therefore, one of the first proteins secreted by fungal pathogens during infection is polygalacturonases (PGs), a member of cell wall degrading enzymes (CWDEs). PGs cause host tissue maceration by degrading pectin, a key component of plant cell wall. Polygalacturonases inhibiting proteins (PGIPs), a leucine-rich repeat (LRR) protein, have long been known (since its discovery in 1971) to impede the activity of PGs and improve plant defense. Nevertheless, identification of PGIP-inactivating effector 1 (PINE1), a small fungal effector protein negating the activity of Arabidopsis PGIP1 by enhancing PG-PGIP dissociation, has posed serious challenges to PGIP-mediated plant immunity. Therefore, in this project, we seek to engineer chickpea PGIP1 (CaPGIP1) to bypass B. cinerea PINE1 (BcPINE1) recognition ensuing increased PG-PGIP interaction and reduced fungal infection. We propose to generate two in silico models, (i) BcPG1–CaPGIP1 and (ii) BcPINE1–CaPGIP1 and compare their interactions using molecular dynamics (MD) simulations to identify key amino acid residues exclusive to BcPINE1–CaPGIP1 interaction. Subsequently, we will validate the role of identified amino acid residues (by site-directed mutagenesis) in CaPGIP1 recognition by BcPINE1 using biophysical (Isothermal Titration Calorimetry) and biochemical (Co-immunoprecipitation assay) techniques. Post-validation, selected CaPGIP1 mutant(s) will be introduced into Arabidopsis pgip1 mutant background for complementation. The Arabidopsis lines will be analyzed for the impact of CaPGIP1 engineering on immune responses against B. cinerea infection. Once established in Arabidopsis, we plan to translate the findings in chickpea to enhance chickpea resistance to B. cinerea infection. With natural resistance genes against B. cinerea not yet known in chickpea, the project can have long-term implications in mitigating B. cinerea infections in chickpea plants. Considering the central role of PGIPs in plant immunity, the concept of targeting PGIP-PINE interaction can also be extended to other crops for disease control.