Tomato mutants sensitive to abiotic stress display different abscisic acid content and metabolism during germination

Abstract

AbstractWe report the determination of abscisic acid (ABA) and its metabolites, phaseic acid (PA), dihydrophaseic acid (DPA) and ABA glucose ester (ABA-GE), in non-dormant dry and imbibed seeds of tomato (Solanum lycopersicumMill.) cv. Moneymaker (wild type), and itstss1,tss2andtos1mutants. High ABA in dry seeds may originate from ABA accumulation in the sheath tissue, which was in contact with an ABA-containing medium, the endocarpus. The highest germination percentages at 72 h, observed intss1andtss2, coincided with minimal ABA content. Wild-type and mutant seeds showed different ABA and catabolic patterns, and these were correlated with their sensitivity to abiotic stress. Whereas dry seeds showed a high basal ABA, imbibed seeds showed higher ABA metabolite content, particularly DPA. The dramatic decrease of ABA following seed imbibition suggests an activation of ABA catabolism during the early stages of the germination process. The observed variation of ABA metabolites among dry and imbibed seeds ofSolanum lycopersicumcv. Moneymaker and itstss1,tss2andtos1mutants shows that ABA metabolism is differentially regulated in these genotypes.