Guard cells of V. faba were prepared by sonicating epidermal Peels andtreated with ABA, mannitol and Ca2+.RNAs extracted from leaf tissue andguard cells were hybridized with RNAprobes of several representative RABgenes. An RNA with a sequence cognated to Pea dehydrin (psdhn1 ) was detected in water-stressed leaves and inthe guard cells treated with ABA for 1and 6 h (Figs. 1 & 2). No RNA cognate to osmotin gene was detected in either tissue preparation. No differencewas found between the transcripts ofRAB genes from whole leaves and thosefrom guard cells (Fig. 1). ABA, butnot Ca2+, was required for the formation of sequence cognated to psdhn1 inguard cells. Exogenous osmotun did notpromote the formation of the RNA sequence.
