Enhanced expression of a nuclease gene in leaves of barley plants under salt stress.

We isolated a cDNA clone, Bnuc1, encoding a nuclease I from leaves of salt-stressed barley (Hordeum vulgare L. cv. Haruna-nijyo) by the differential display method. Northern blot analysis revealed that the transcript of Bnuc1 gene was increased dramatically in barley leaves under salt stress. The expression of Bnuc1 gene was also increased by exogenously applied abscisic acid (ABA) in leaves, but not by gibberellic acid (GA) during seed germination. Furthermore, Bnuc1 gene was expressed more in old leaves than in young leaves during both salt stress and natural senescence. Salt-inducible nuclease activity possibly corresponding to the Bnuc1 gene was detected, and was much higher in old leaves than in young leaves under salt stress.