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Deciphering the role of g-proteins in response to oxalic acid

Student name: Ms Ritu Raheja
Guide: Dr Ramakrishnan Sitaraman
Year of completion: 2018
Host Organisation: National Institute of Plant Genome Research (NIPGR), New Delhi
Supervisor (Host Organisation): Dr Naveen Chandra Bisht
Abstract: Oxalic acid (OA) is a well-known phytotoxin secreted by necrotrophic fungus Sclerotinia sclerotiorum during ingression in plants. This necrotrophic fungus causes a severe loss of crop yield in more than forty plant species. In plants, biosynthesis of OA has a role to play in growth and development. OA biosynthesis can account for 3-15% of a plant’s dry weight, depending on the species. However, OA is toxic to plants at high concentrations. G-proteins are also better known for defense against a variety of pathogens in a number of plant species. Therefore, Physiological assay and cell death assay are the two methods conducted to get support in favor of idea that G-proteins have some role in defense and development of Arabidopsis plant when exposed to OA. Triple mutant which is a knock out mutant of G-proteins and wild type (Col-0) Arabidopsis plants are used in this study. During physiological study, 4mM concentration of OA induced root growth inhibition in both Col-0 and triple mutant seedlings of Arabidopsis. However, percentage reduction in root growth was more in triple mutant seedlings when compared to seedlings of Col-0.In this study, two different histological assays namely DAB and Trypan blue staining were used for used for analysis of cell death caused by oxalic acid in Arabidopsis plant. Leaf disks of triple mutant Arabidopsis treated with OA showed more up-take of DAB and Trypan blue staining than Col-0 indicating more cell death in triple mutant leaf disks than Col-0 when exposed to OA. Both observations accumulate evidences in support of G-proteins playing some role in response to oxalic acid.

Keywords: G-protein, oxalic acid, programmed cell death, root length, Sclerotinia sclerotiorum.