摘要：Gibberellin (GA) negatively affects color evolution and other ripening-related processes in non-climacteric fruits. The bioactive GA, gibberellic acid (GA
3), is commonly applied at the light green-to-straw yellow transition to increase firmness and delay ripening in sweet cherry (
Prunus avium L.), though causing different effects depending on the variety. Recently, we reported that GA
3 delayed the IAD parameter (a ripening index) in a mid-season variety, whereas GA
3 did not delay IAD but reduced it at ripeness in an early-season variety. To further explore this contrasting behavior between varieties, we analyzed the transcriptomic responses to GA
3 applied on two sweet cherry varieties with different maturity time phenotypes. At harvest, GA
3 produced fruits with less color in both varieties. Similar to our previous report, GA
3 delayed fruit color initiation and IAD only in the mid-season variety and reduced IAD at harvest only in the early-season variety. RNA-seq analysis of control- and GA
3-treated fruits revealed that ripening-related categories were overrepresented in the early-season variety, including ‘photosynthesis’ and ‘auxin response’. GA
3 also changed the expression of carotenoid and abscisic acid (ABA) biosynthetic genes in this variety. In contrast, overrepresented categories in the mid-season variety were mainly related to metabolic processes. In this variety, some
PP2Cs putative genes were positively regulated by GA
3, which are negative regulators of ABA responses, and
MYB44-like genes (putative repressors of
PP2Cs expression) were downregulated. These results show that GA
3 differentially modulates the transcriptome at the onset of ripening in a variety-dependent manner and suggest that GA
3 impairs ripening through the modification of ripening associated gene expression only in the early-season variety; whereas in the mid-season variety, control of the ripening timing may occur through the
PP2C gene expression regulation. This work contributes to the understanding of the role of GA in non-climacteric fruit ripening.
