Browsing by Author "Vani, Gubbala"

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Arsenic stress activates MAP kinase in rice roots and leaves
(Elsevier, 2011) Rao, Kudupudi Prabhakara; Vani, Gubbala; Kumar, Kundan; Wankhede, Dhammaprakash Pandhari; Misra, Mohit; Gupta, Meetu; Sinha, Alok Krishna
The toxic metalloid arsenite has become a potential threat to rice growing regions leading to serious contamination in food chain. In the present study effect of different physiological concentration of arsenite that is toxic and triggers the molecular events were evaluated in rice seedlings. Along with severe effect on the growth of rice seedling, production of reactive oxygen species (ROS) and nitric oxide (NO) in arsenite treated rice roots was also observed. Activation of a 42kDa mitogen activated protein kinase (MAPK/MPK) by arsenite was observed in rice leaves and 42 and 44kDa in roots in dose dependent manner. The activated MAPK could be immunoprecipitated with anti-phospho-tyrosine antibody, 4G10. The kinetic of MAPK activation by arsenite was found to be dose dependent. Transcript analysis of MAPK family and immunokinase assay in arsenite treated rice seedling revealed significant level of induction in OsMPK3 transcripts in leaves and OsMPK3, OsMPK4 transcripts in roots. Among MAPK kinase (MKKs) gene family, OsMKK4 transcripts were found to be induced in arsenite treated rice leaves and roots. In-silico homology modeling and docking analysis supported OsMPK3-OsMKK4 interaction. The data indicates that arsenite stress is transduced through MAPK signaling cascade in rice.
Rhythmic expression of mitogen activated protein kinase activity in rice
(Springer, 2009) Rao, Kudupudi Prabhakara; Vani, Gubbala; Kumar, Kundan; Sinha, Alok Krishna
Mitogen activated protein kinase (MAPK) are known to get activated during various stress signals and transduce the message from the cell membrane to the nucleus for appropriate cellular reorganization. Though, a certain basal activity of MAPK is often observed in the control plants. Prolonged exposure of rice plants to lowered or elevated temperature exhibited a rhythm in the activation of MAPKs. We analyzed existence of a possible endogenous rhythm in the activity of MAPKs in rice plants. The plants growing at constant temperature entrained in 16/8 h day-night cycle showed diurnal rhythm in activity. When the activation of MAPK was tested under continuous conditions by shifting plants to continuous darkness for a period of 72 h, the periodic rhythm persisted and followed a circadian pattern. Analysis of the transcripts of group A, B and C members of MAPKs under above conditions by quantitative real time PCR revealed that the members of group C exhibit periodic rhythm. Our data indicates that the MAP kinase activity in rice follows rhythmic expression in a circadian manner.