Browsing by Author "Rai, Neeraj Kumar"

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cDNA-AFLP analysis reveals differential gene expression in response to salt stress in foxtail millet (Setaria italica L.)
(Springer, 2008) Jayaraman, Ananthi; Puranik, Swati; Rai, Neeraj Kumar; Vidapu, Sudhakar; Sahu, Pranav Pankaj; Lata, Charu; Prasad, Manoj
Plant growth and productivity are affected by various abiotic stresses such as heat, drought, cold, salinity, etc. The mechanism of salt tolerance is one of the most important subjects in plant science as salt stress decreases worldwide agricultural production. In our present study we used cDNA-AFLP technique to compare gene expression profiles of a salt tolerant and a salt-sensitive cultivar of foxtail millet (Seteria italica) in response to salt stress to identify early responsive differentially expressed transcripts accumulated upon salt stress and validate the obtained result through quantitative real-time PCR (qRT-PCR). The expression profile was compared between a salt tolerant (Prasad) and susceptible variety (Lepakshi) of foxtail millet in both control condition (L0 and P0) and after 1 h (L1 and P1) of salt stress. We identified 90 transcript-derived fragments (TDFs) that are differentially expressed, out of which 86 TDFs were classified on the basis of their either complete presence or absence (qualitative variants) and 4 on differential expression pattern levels (quantitative variants) in the two varieties. Finally, we identified 27 non-redundant differentially expressed cDNAs that are unique to salt tolerant variety which represent different groups of genes involved in metabolism, cellular transport, cell signaling, transcriptional regulation, mRNA splicing, seed development and storage, etc. The expression patterns of seven out of nine such genes showed a significant increase of differential expression in tolerant variety after 1 h of salt stress in comparison to salt-sensitive variety as analyzed by qRT-PCR. The direct and indirect relationship of identified TDFs with salinity tolerance mechanism is discussed.
Dynamics of defense related components in two contrasting genotypes to tomato upon infection with tomato leaf curl New Delhi virus
(Springer, 2012) Sahu, Pranav Pankaj; Rai, Neeraj Kumar; Puranik, Swati; Roy, Anirban; Khan, Moinuddin; Prasad, Manoj
Tomato leaf curl virus (ToLCV) disease is a serious threat for tomato cultivation in the tropics and subtropics. Despite serious efforts no immune commercial varieties or F(1) hybrids are available till date. In this study, the interaction between Solanum lycopersicum and ToLCV was characterized on molecular and biochemical basis. RNA silencing mediated by short interfering RNA (siRNA) and reactive oxygen species (ROS) has been proposed as central components of plant adaptation to several stresses. A comparative RNA interference study between two contrasting tomato genotypes, LA1777 (tolerant) and 15SBSB (susceptible) infected with Tomato Leaf Curl New Delhi Virus (ToLCNDV) revealed relatively higher accumulation of siRNA in the leaves of tolerant genotype. In LA1777, ToLCNDV produced chlorotic as well as necrotic areas at the inoculation sites 5-10 days post-inoculation. Caspase-9- and caspase-3-like activities were significantly increased in response to ToLCNDV infection in LA1777 at inoculated region. Activities of antioxidant enzymes involved in the detoxification of ROS were examined in both systemic and localized area of infection, and their expression level was further validated through quantitative real-time PCR of the corresponding transcripts. Expression patterns of three genes encoding pathogenesis-related proteins showed higher accumulation in tolerant genotype. Tolerance against the ToLCNDV in LA1777 can be attributed to the higher siRNA accumulation, localized cell death, altered levels of antioxidant enzymes and activation of pathogenesis-related genes at different durations of virus infection. Based on these direct and indirect evidences, we have proposed a putative mechanism for ToLCNDV tolerance in the tolerant genotype.