Interplay of Calcium and Nitric Oxide in improvement of Growth and Arsenic-induced Toxicity in Mustard Seedlings
Rachana Singh, Parul Parihar, Sheo Mohan Prasad
Abstract
Abstract In this study, Ca 2+ 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: F v , F m , F v /F o , F m /F o , ФP o or F v /F m , Ψ o , ФE o , PI ABS , Area and N and redox status (AsA/DHA and GSH/GSSG ratios) of the cell; whereas energy flux traits: ABS/RC , TR o /RC , ET o /RC and DI o /RC along with F o , F o /F v , F o /F m , ФD o and S m ) were enhanced. Further, addition of EGTA (Ca 2+ scavenger) and LaCl 3 (plasma membrane Ca 2+ 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 Ca 2+ and NO supplementation, respectively to As stressed seedlings thereby indicating their signalling behaviour. Further, to investigate the link between Ca 2+ 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 Ca 2+ , thereby signifying that NO plays crucial role in Ca 2+ mediated signalling. In addition, As accumulation, ROS and their indices, antioxidant system, NO accumulation and thiol compounds were also studied that showed varied results.