Transcriptomic investigations of gene networks in response to arsenic accumulation in Brassica juncea (L.) Czern & Coss
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Arsenic (As), a widespread toxic metalloid is class I carcinogen known to cause adverse health effects in human. In the present study, As accumulation potential and differential gene expression in B. juncea is investigated. The amount of arsenic accumulated varied in the range of 15.99 to 1138.70 mg/Kg on dry weight basis in five cultivars. A decrease in chlorophyll content and increase in membrane damage and enzymatic activities of antioxidants was observed with increase in As concentration in the B. juncea cultivars. Using maximum As accumulating cultivar (RLM514), a total of 10,870 significantly differentially expressed transcripts in response to As treatment were identified. Further, the pathway analysis revealed a large scale reprogramming of genes involving carbon metabolism (2.5%), plant hormone signaling (1.4%), and glutathione metabolism (0.6%). Moreover, a comparative account of Cd toxicity revealed a total of 11,294 transcripts to be significantly differentially expressed. The genes related to response to chemical, oxidative stress, transport, and secondary metabolism were upregulated whereas multicellular organismal development, developmental process, photosynthesis were downregulated by Cd treatment. Furthermore, 616 membrane transport proteins were found to be significantly differentially expressed. Cd-related transporters such as metal transporter (Nramp1), metal tolerance protein (MTPC2, MTP11), cadmiumtransporting ATPase, and plant cadmium resistance protein (PCR2, PCR6) were upregulated while cadmium/zinc- transporting ATPase (HMA2, HMA3, HMA4), highaffinity calcium antiporter (CAX1), and iron transport protein (IRT1) were downregulated by Cd treatment. Pathway analysis revealed signaling cascades including plant hormones signaling, MAPK signaling and Ca signaling was modulated suggesting their role in Cd-stress tolerance. The regulation overview using MapMan also revealed gene expression related to plant hormones, calcium regulation and MAP kinases were altered under Cd-stress.
- PhD 
- Plant Sciences-Research Publications