Abstract
Among major crops, generally, barley is moderately tolerant, but rice is sensitive to salt stress. To obtain insight into the differences of the mechanism of salt tolerance, cDNA microarray was fabricated using barley salt-responsive genes, and expression profilings were compared between barley and rice during initial phase of salt stress. Up-regulation of many genes were observed in barley, but not in rice. Early regulation of the gene expressions invovled in osmotic adjustment was observed in barley. Whereas, up-regulation of the gene expressions invovled in regulation of ion-homeostasis was commonly observed in both barley and rice. Salt-inducibility of some genes/proteins was confirmed by realtime-PCR and western blot. Thus, the results of comparative expression analyses interpreted the differences in early response to salt stress between barley and rice, and this might be one of the reasons why they differ in their ability to tolerate salt stress.
