Influence of calcium on nitrate starvation response of bread wheat

Calcium is an omnipresent secondary messenger that plays a major role in response to various biotic and abiotic responses. Nitrate is a major form of nitrogen taken up by many plants, including wheat. Calcium plays an important role in the regulation of nitrate transporters and is involved in nitrate signalling in primary nitrate response. But information about the role of calcium in response to nitrate starvation is scarce. In this study, we used B.T.Schomburgk a nitrate use efficient genotype of bread wheat which was exposed to three different treatment 0 mM NO 3 − , 0 mM NO 3 − + 5 mM Ca 2+ and 0 mM NO 3 − + 5 mM Ca 2+ + 5 mM EGTA (Ca 2+ chelator). A high calcium level was found to enhance the expression of the negative regulator of NO 3 − response, LBD37 and 38 . These, in turn, down-regulate the NRT2.1 , NR expression and NR activity. A high Ca 2+ supply curtailed anthocyanin content and expression of its biosynthetic genes. Higher Ca 2+ enhanced the root growth after two days of exposure while reduced its growth after ten days of exposure. Thus the cytoplasmic Ca 2+ level regulates the nitrate starvation response in a dose-dependent manner.