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

Abstract

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 virus-induced gene silencing technique in strawberry fruit, the expression of a 9-cis-epoxycarotenoid dioxygenase gene (FaNCED1), 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 FaNCED1-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.

SUCROSE NONFERMENTING1-RELATED PROTEIN KINASE2.6, an Ortholog of OPEN STOMATA1, Is a Negative Regulator of Strawberry Fruit Development and Ripening

“…Previous studies demonstrated that ABA as well as PYR1 and FaABI1 were involved in the regulation of strawberry fruit development and ripening Jia et al, 2011Jia et al, , 2013a. It is not surprising that PYR1 and ABI1 are implicated in strawberry fruit development and ripening, because molecular interaction between PYR and ABI1 is required to initiate ABA signaling.…”

The effect of phytohormones on the growth, cellulose production and pellicle properties of Gluconacetobacter xylinus ATCC 53582

“…For example, immature strawberry seeds secrete auxins but when ripening starts IAA production stops. 51 We further speculate that G. xylinus may metabolize exogenous IAA reducing its effective concentration so that ripening can commence. There are several examples of plant-associated bacteria capable of degrading auxins.…”

“…Exogenous IAA impedes G. xylinus cellulose synthesis yet stimulates growth rate so that cellular density is at a peak when the fruit ripens and glucose becomes more readily available. During ripening, IAA production ceases, 51 alleviating the inhibition of bacterial cellulose synthesis. For example, immature strawberry seeds secrete auxins but when ripening starts IAA production stops.…”

Gene Expression and Metabolite Profiling of Developing Highbush Blueberry Fruit Indicates Transcriptional Regulation of Flavonoid Metabolism and Activation of Abscisic Acid Metabolism

“…Strawberry, for example, also shows an increase in ABA in parallel with color formation and ripening. Furthermore, RNAi-mediated silencing of the FaNCED1 gene reduced ABA accumulation and also inhibited anthocyanin synthesis of strawberry fruit (Jia et al, 2011), which functionally links ABA with ripening processes. In grape, both drought-induced or exogenous ABA leads to elevated anthocyanin synthesis and anthocyanin-related gene expression, providing a strong link between ABA metabolism and anthocyanin synthesis (Coombe and Hale, 1973;Peppi et al, 2008;Koyama et al, 2010;Wheeler et al, 2009).…”

“…By contrast, the application of ABA to grape can hasten ripening and increase anthocyanin and sugar contents (Peppi et al, 2008). In strawberry, the central role of ABA was recently demonstrated directly, since the RNA interference (RNAi)-mediated silencing of an ABA biosynthetic and putative ABA receptor gene led to the inhibition of anthocyanin production (Jia et al, 2011).…”