Abstract
Abscisic acid (ABA) is a vital phytohormone that accumulates in response to various biotic and abiotic stresses, as well as plant growth. In Arabidopsis thaliana, there are 14 members of the ABA receptor family, which are key positive regulators involved in ABA signaling. Besides reduced drought stress tolerance, the quadruple and sextuple mutants (pyr1pyl1pyl2pyl4 (1124) and pyr1pyl1pyl2pyl4pyl5pyl8 (112458) show abnormal growth phenotypes, such as decreases in yield and height, under non-stress conditions. However, it remains unknown whether ABA receptors mediate ABA signaling to regulate plant growth and development. Here, we showed the primary metabolite profiles of 1124, 112458 and wild-type (WT) plants grown under normal conditions. The metabolic changes were significantly different between ABA receptor mutants and WT. Guanosine, for the biosynthesis of cyclic guanosine 3′,5′-monophosphate (cGMP), is an important second messenger that acts to regulate the level of ABA. In addition, other amino acids were increased in the 112458 mutant, including proline. These results, together with phenotype analysis, indicated that ABA receptors are involved in ABA signaling to modulate metabolism and plant growth under normal conditions.
Highlights
Abscisic acid (ABA) is a key hormone involved in plant growth and development, including seed dormancy and germination, root system development, leaf senescence, flowering transformation, seed and fruit ripening [1]
These results are consistent with the extreme ABA-insensitive phenotype of the 112458 mutant in germination and seedling establishment assays [16]
Compared with the wild type, lower growth was observed in 1124 and 112458 plants, which lost the function of binding ABA, they were able to flower and produce viable seeds (Figure 1C)
Summary
Abscisic acid (ABA) is a key hormone involved in plant growth and development, including seed dormancy and germination, root system development, leaf senescence, flowering transformation, seed and fruit ripening [1]. It plays an important role in plant stress adaptation [1,2,3]. The ABA receptors, known as the PYRABACTINRESISTANT/PYRABACTIN RESISTANT-LIKE/REGULATORY COMPONENT. ABA receptors constitute a 14-member family, which is found in higher plants [7,8]. Subgroup I members interact with the PP2Cs, and generate the high-affinity interaction at basal levels of ABA.
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