The role of FaBG3 in fruit ripening and B. cinerea fungal infection of strawberry

Abstract

These authors contributed equally to this work. SUMMARYIn plants, b-glucosidases (BG) have been implicated in developmental and pathogen defense, and are thought to take part in abscisic acid (ABA) synthesis via hydrolysis of ABA glucose ester to release active ABA; however, there is no genetic evidence for the role of BG genes in ripening and biotic/abiotic stress in fruits. To clarify the role of BG genes in fruit, eight Fa/FvBG genes encoding b-glucosidase were isolated using information from the GenBank strawberry nucleotide database. Of the Fa/FvBG genes examined, expression of FaBG3 was the highest, showing peaks at the mature stage, coincident with the changes observed in ABA content. To verify the role of this gene, we suppressed the expression of FaBG3 via inoculation with Agrobacterium tumefaciens containing tobacco rattle virus carrying a FaBG3 fragment (RNAi). The expression of FaBG3 in FaBG3-RNAi-treated fruit was markedly reduced, and the ABA content was lower than that of the control. FaBG3-RNAi-treated fruit did not exhibit full ripening, and were firmer, had lower sugar content, and were pale compared with the control due to down-regulation of ripening-related genes. FaBG3-RNAi-treated fruit with reduced ABA levels were much more resistant to Botrytis cinerea fungus but were more sensitive to dehydration stress than control fruit. These results indicate that FaBG3 may play key roles in fruit ripening, dehydration stress and B. cinerea fungal infection in strawberries via modulation of ABA homeostasis and transcriptional regulation of ripening-related genes.

Abscisic acid and sucrose regulate tomato and strawberry fruit ripening through the abscisic acid‐stress‐ripening transcription factor

“…On the other hand, in strawberry, the high gene expression levels of the FaSUT and FaSPS genes, and the low gene expression levels of the FaAI and FaSS genes resulted in a higher rate of sucrose accumulation in strawberry fruit (Figure S5a). Similar to the observed changes due to sucrose, in strawberry, the level of expression of the ABA biosynthesis gene, NCED , also consistent with the ABA content during fruit development (Figures S2e and S3b), and ABA activated several ripening‐related genes (Han et al ., ; Jia et al ., ; Li et al ., ; Margherita et al ., ; Molina‐Hidalgo et al ., ; Sun et al ., ). We also determined that the ethylene content peaked in the white strawberry fruit (Figure S2e).…”

Grey mould of strawberry, a devastating disease caused by the ubiquitous necrotrophic fungal pathogen Botrytis cinerea

“…ABA biosynthesis during fruit ripening is triggered by a decrease in pH, turgor changes, sugar accumulation, and the switch of sugars from mainly glucose and fructose to sucrose (Jia et al , ; Li et al , ). Effects of ABA on strawberry susceptibility to fungal disease have not been extensively studied, but down‐regulation of the ABA biosynthetic gene β‐glucosidase FaBG3 has been reported to result in fruit with limited ripening and higher B. cinerea resistance (Li et al ). In tomato, ABA accumulation is related to higher pathogen susceptibility, probably via activation of senescence (Blanco‐Ulate et al , ; Harrison et al , ; Lee et al , ).…”

SlNCED1 and SlCYP707A2: key genes involved in ABA metabolism during tomato fruit ripening

“…In addition, ABA could control, at least in part, the production and effects of ethylene in climacteric tomato fruit. In recent years, tobacco rattle virus-induced gene silencing (VIGS) has been used as a rapid gene function assay system in molecular biological studies of fleshy fruit (Fu et al , 2006; Hoffmann et al , 2006; Li et al , 2013). In this study, we further identify the function of three NCED and three CYP707A genes by VIGS.…”