ALTERATION OF GENE-EXPRESSION ASSOCIATED WITH ABSCISIC ACID-INDUCED CHILLING TOLERANCE IN MAIZE SUSPENSION-CULTURED CELLS

ABA induces chilling tolerance in maize (Zea mays L., cv Black Mexican Sweet) suspension-cultured cells at 28-degrees-C when ABA was added to the culture medium at least 6 h prior to chilling (4-degrees-C), and this induction can be inhibited by blocking protein synthesis with cycloheximide treatment (Z. Xin, P.H. Li 11992] Plant Physiol 99: 707-711). De novo synthesis of proteins and changes in poly(A+) RNAs were investigated during the ABA induction of chilling tolerance at 28-degrees-C as well as during chilling exposure. At 28-degrees-C, ABA increased the net synthesis of 11 proteins. Five of these proteins, whose net synthesis was also increased by chilling (4-degrees-C), were called group I ABA-induced proteins; the remaining six proteins, whose net synthesis was not altered by chilling, were called group II ABA-induced proteins. Chilling suppressed the net synthesis of three proteins. ABA treatment prior to chilling did not alleviate this suppression. ABA applied at the inception of chilling induced neither chilling tolerance nor accumulation of any of the group II proteins; however, once the group II proteins appeared, they were continually synthesized even in a chilling regimen. ABA induced seven in vitro translation products at 28-degrees-C. Three of these products could also be induced by chilling; the remaining four were induced by ABA only at 28-degrees-C. These results suggest that ABA-induced alteration of protein synthesis at 28-degrees-C is associated with an increased chilling tolerance in maize suspension-cultured cells.