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.
Highlights
The gaseous plant hormone ethylene plays an important role in various aspects of plant growth and development, including seed germination, organ senescence, and fruit development, it regulates stress responses to environmental challenge
According to the methods described by Villarreal and others (2010), ethephon treatment of FaSAMS1- and FaCTR1-RNA interference (RNAi) fruit and natural Wt fruit was performed by application of 7 mM ethephon solution, and ethephon-free solution on natural Wt fruit was used as a control
A previous report showed that SAM synthetase (SAMS) transcripts in climacteric Actinidia chinensis fruit were induced during the late ethylene burst as part of the methionine salvage pathway (Whittaker and others 1997), the defined role of SAMS in nonclimacteric fruit remains unclear
Summary
The gaseous plant hormone ethylene plays an important role in various aspects of plant growth and development, including seed germination, organ senescence, and fruit development, it regulates stress responses to environmental challenge (reviewed by Fluhr and Mattoo 1996). The effect of ethylene on climacteric fruit ripening and its signaling transduction pathways have been studied extensively in the past decades. Was it found that there is an essential role for this hormone in the regulation of climacteric fruit ripening, but a defined model for its mechanism of action was established (reviewed by Gray and others 1994; Giovannoni 2001, 2004; Alexander and Grierson 2002; AdamsPhillips and others 2004; Prasanna and others 2007; Bapat and others 2010; Klee and Giovannoni 2011). The ethylene biosynthesis and signaling transduction pathways in the model plant
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