Abscisic Acid Plays an Important Role in the Regulation of Strawberry Fruit Ripening

• Published in: Plant physiology (Bethesda) 2011-09, Vol.157 (1), p.188-199
• Main Authors: Jia, Hai-Feng, Chai, Ye-Mao, Li, Chun-Li, Lu, Dong, Luo, Jing-Jing, Qin, Ling, Shen, Yuan-Yue
• Format: Article
• Language: English
• Subjects: Abscisic Acid - physiology; Base Sequence; Biological and medical sciences; Biosynthesis; DEVELOPMENT AND HORMONE ACTION; DNA Primers; Down regulation; Fragaria - genetics; Fragaria - physiology; Fruits; Fundamental and applied biological sciences. Psychology; Gene expression regulation; Gene Silencing; Genes, Plant; Molecular Sequence Data; Phenotypes; Plant physiology and development; Plants; Plants, Genetically Modified; Real-Time Polymerase Chain Reaction; Receptors; Ripening; RNA; RNA Interference; RNA Processing, Post-Transcriptional; Sugars
• ISSN: 0032-0889; 1532-2548; 1532-2548
• DOI: 10.1104/pp.111.177311

The plant hormone abscisic acid (ABA) has been suggested to play a role in fruit development, but supporting genetic evidence has been lacking. Here, we report that ABA promotes strawberry (Fragaria ananassa) fruit ripening. Using a newly established Tobacco rattle y/n/s-induced gene silencing technique in strawberry fruit, the expression of a 9-cis-epoxycarotenoid dioxygenase gene (FaNCEDl), which is key to ABA biosynthesis, was down-regulated, resulting in a significant decrease in ABA levels and uncolored fruits. Interestingly, a similar uncolored phenotype was observed in the transgenic RNA interference (RNAi) fruits, in which the expression of a putative ABA receptor gene encoding the magnesium chelatase H subunit (FaCHLH/ABAR) was down-regulated by virus-induced gene silencing. More importantly, the uncolored phenotype of the FENCED!-downregulated RNAi fruits could be rescued by exogenous ABA, but the ABA treatment could not reverse the uncolored phenotype of the FaCHLH/ABAR-down-regulated RNAi fruits. We observed that down-regulation of the FaCHLH/ABAR gene in the RNAi fruit altered both ABA levels and sugar content as well as a set of ABA-and/or sugar-responsive genes. Additionally, we showed that exogenous sugars, particularly sucrose, can significantly promote ripening while stimulating ABA accumulation. These data provide evidence that ABA is a signal molecule that promotes strawberry ripening and that the putative ABA receptor, FaCHLH/ABAR, is a positive regulator of ripening in response to ABA.