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

The effects of salt stress and abscisic acid (ABA) on the expression of betaine aldehyde dehydrogenase (BADH) were determined in sorghum (Sorghum bicolor L.) plants. BADH mRNA expression was induced by salinity, and the timing coincided with the observed glycinebetaine (betaine) accumulation. The leaf water potential in the leaves of the sorghum plants was significantly affected by salinity. In response to salinity, betaine, ABA, Na and Cl accumulations increased 6-, 16-, 90-, and 3-fold, respectively. In the leaf disks from unsalinized plants incubated on NaCl, or ABA solution, the BADH mRNA level 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. The results indicate that the salt-induced accumulation of betaine and BADH mRNA coincides with the presence of ABA.