摘要：In this study, Ca2 mediated NO signalling was studied in response to metalloid (As) stress in Brassica seedlings. Arsenic toxicity strongly suppressed the growth (fresh weight, root and shoot length), photosynthetic pigments, Chl a fluorescence indices (Kinetic traits: Fv, Fm, Fv/Fo, Fm/Fo, ФPo or Fv/Fm, Ψo, ФEo, PIABS, Area and N and redox status (AsA/DHA and GSH/GSSG ratios) of the cell; whereas energy flux traits: ABS/RC, TRo/RC, ETo/RC and DIo/RC along with Fo, Fo/Fv, Fo/Fm, ФDo and Sm) were enhanced. Further, addition of EGTA (Ca2 scavenger) and LaCl3 (plasma membrane Ca2 channel blocker) to As Ca; while c‒PTIO (NO scavenger) and l‒NAME (NO synthase inhibitor) to As SNP treated seedlings, siezed recovery on above parameters caused due to Ca2 and NO supplementation, respectively to As stressed seedlings thereby indicating their signalling behaviour. Further, to investigate the link between Ca2 and NO, when c‒PTIO and l‒NAME individually as well as in combination were supplemented to As Ca treated seedlings; a sharp inhibition in above mentioned traits was observed even in presence of Ca2 , thereby signifying that NO plays crucial role in Ca2 mediated signalling. In addition, As accumulation, ROS and their indices, antioxidant system, NO accumulation and thiol compounds were also studied that showed varied results.
