Effect of salinity and abscisic acid on accumulation of glycinebetaine andbetaine aldehyde dehydrogenase mRNA in Sorghum leaves (Sorghum bicolor)

The effects of salt stress and abscisic acid (ABA) on the expression of bet aine aldehyde dehydrogenase (BADH) were determined in sorghum (Sorghum bico lor L.) plants. BADH mRNA expression was induced by salinity, and the timin g coincided with the observed glycinebetaine (betaine) accumulation. The le af water potential in the leaves of the sorghum plants was significantly af fected by salinity. In response to salinity, betaine, ABA, Na and Cl accumu lations increased 6-, 16-, 90-, and 3-fold, respectively in the leaf disks from unsalinized plants incubated on NaCl, or ABA solution, the BADH mRNA l evel was lower than in the ABA-treated disks. Exogenous application of the ABA biosynthetic inhibitor fluridone to the NaCl-treated disks reduced the ABA accumulation and BADH mRNA levels compared with NaCl-treated leaves. Th e results indicate that the salt-induced accumulation of betaine and BADH m RNA coincides with the presence of ABA.