Abscisic acid and stress regulate gene expression during germination of chick‐pea seeds. Possible role of calcium

Abstract

A cDNA library has been constructed using poly (A+) RNA isolated from embryonic axes of chick‐pea (Cicer arietinum L. cv. Castellana) seeds germinated for 12 h in 50 μM abscisic acid (ABA). By differential screening three clones (designated GAB‐8, GAB‐9, GAB‐11) regulated by ABA were identified. Northern analysis of these clones revealed that their transcripts decline early during normal germination but are maintained or even increased by exogenous ABA. The levels of these transcripts were analyzed after subjecting seeds to stressful conditions (low and high temperature, osmotic and saline stress). Each of them responded differently to the conditions used. Only effects of high temperature and osmotic stress on transcript levels could be correlated with the effect of ABA in the seed. The possible role of calcium on mRNA accumulation was studied, revealing that the expression of the ABA‐regulated clones seems to depend on the presence of calcium ions, suggesting that calcium is involved in the response of the seeds to ABA.