New Evidence for the Role of Ethylene in Strawberry Fruit Ripening

Abstract

It has been suggested that the phytohormone ethylene plays a role in strawberry fruit ripening, and new genetic evidence for the role of this hormone in strawberry ripening is provided in this study. The combined analysis of ethylene production and transcripts of the ethylene biosynthesis-related gene FaSAMS1 and the signaling gene FaCTR1 in 'Camarosa' strawberry (Fragaria ananassa) fruit showed that an increase in ethylene production was concomitant with a rise in transcripts of the two genes during fruit red-coloring, suggesting that FaSAMS1 and FaCTR1 might play a role in fruit ripening. Downregulation of the FaSAMS1 or FaCTR1 transcript via a recently reported tobacco rattle virus-induced gene-silencing technique not only inhibited fruit red-coloring and firmness, but it also promoted ethylene biosynthesis. Furthermore, the latter also affected a series of ethylene-signaling components. Importantly, applied ethephon could promote natural strawberry fruit red-coloring and softening and partially rescue anthocyanin biosynthesis in the two-type RNAi fruit, but could not markedly affect RNAi fruit firmness. These data provide new evidence that FaCTR1 positively regulates strawberry fruit ripening and that ethylene is required for strawberry fruit ripening.

Effect of ethylene treatment on phytochemical and ethylene-related gene expression during ripening in strawberry fruit Fragaria x ananassa cv. Camino Real

“…Non-climacteric fruits are able to synthesize ethylene; therefore, the involvement of this hormone in physiological and molecular events has been reported during strawberry development and ripening (Trainotti et al, 2005;Villarreal et al, 2010;Merchante et al, 2013;Sun et al, 2013).…”

Cloning, expression, and enzymatic activity analysis of strawberry S-adenosyl-L-metnionine synthetase gene FaSAMS1

“…Although SAM synthetase committed the first step in ethylene biosynthesis is proved to plays a role in strawberry fruit ripening (Sun et al, 2013), the biochemical properties of FaSAMS1 protein remain unclear. In the present study, it is confirmed that FaSAMS1had high enzymatic activity.…”

“…Especially, much progress has been made in understanding the molecular mechanisms of ethylene in the regulation of climacteric fruit ripening using the model plant tomato (Klee and Giovannoni, 2011). Notably, in recent years, ethylene is also involved in the regulation of non-climacteric fruit ripening using the model plant strawberry (Sun et al, 2013), demonstrating that downregulation of the ethylene biosynthesis-related gene FaSAMS1inhibits ripening. However, the biochemical nature of the FaSAMS1 protein remains yet unknown.…”

“…Owing to a critical role of ethylene in triggering tomato fruit ripening, to a large extent, this model has also been further developed in the fruit (Barry and Giovannoni, 2007), finding that ACC synthase LeACS2 and ACC oxidase LeACO1 control tomato fruit ethylene production and tomato ethylene receptor tCTR1 is induced by both ripening and exogenous ethylene (Klee, 2002). Downregulation of FaSAMS1 or FaCTR1 transcripts not only inhibits strawberry fruit red-coloring, but also applied ethephon could promote natural strawberry fruit red-coloring and softening, as well as rescues partially anthocyanin biosynthesis in the RNAi fruit, demonstrating that ethylene is required for strawberry fruit ripening (Sun et al, 2013). Although SAM synthetase committed the first step in ethylene biosynthesis is proved to plays a role in strawberry fruit ripening (Sun et al, 2013), its biochemical properties of FaSAMS1 protein remain unclear.…”

“…Downregulation of FaSAMS1 or FaCTR1 transcripts not only inhibits strawberry fruit red-coloring, but also applied ethephon could promote natural strawberry fruit red-coloring and softening, as well as rescues partially anthocyanin biosynthesis in the RNAi fruit, demonstrating that ethylene is required for strawberry fruit ripening (Sun et al, 2013). Although SAM synthetase committed the first step in ethylene biosynthesis is proved to plays a role in strawberry fruit ripening (Sun et al, 2013), its biochemical properties of FaSAMS1 protein remain unclear.…”