The strawberry (Fragaria×ananassa) fruit-specific rhamnogalacturonate lyase 1 (FaRGLyase1) gene encodes an enzyme involved in the degradation of cell-wall middle lamellae

Abstract

Pectins are essential components of primary plant cell walls and middle lamellae, and are related to the consistency of the fruit and its textural changes during ripening. In fact, strawberries become soft as the middle lamellae of cortical parenchyma cells are extensively degraded during ripening, leading to the observed short post-harvest shelf life. Using a custom-made oligonucleotide-based strawberry microarray platform, a putative rhamnogalacturonate lyase gene (FaRGlyase1) was identified. Bioinformatic analysis of the FaRGlyase1 sequence allowed the identification of a conserved rhamnogalacturonate lyase domain, which was also present in other putative RGlyase sequences deposited in the databases. Expression of FaRGlyase1 occurred mainly in the receptacle, concurrently with ripening, and it was positively regulated by abscisic acid and negatively by auxins. FaRGLyase1 gene expression was transiently silenced by injecting live Agrobacterium cells harbouring RNA interference constructs into fruit receptacles. Light and electron microscopy analyses of these transiently silenced fruits revealed that this gene is involved in the degradation of pectins present in the middle lamella region between parenchymatic cells. In addition, genetic linkage association analyses in a strawberry-segregating population showed that FaRGLyase1 is linked to a quantitative trait loci linkage group related to fruit hardness and firmness. The results showed that FaRGlyase1 could play an important role in the fruit ripening-related softening process that reduces strawberry firmness and post-harvest life.

An R2R3-MYB Transcription Factor Regulates Eugenol Production in Ripe Strawberry Fruit Receptacles

“…5). This expression model has been described for other receptacle-specific and ripening-related genes (Moyano et al, 1998;Blanco-Portales et al, 2002;Raab et al, 2006;Cumplido-Laso et al, 2012;Molina-Hidalgo et al, 2013). On the contrary, when ABA content in the receptacle was diminished by transient silencing of FaNCED1 expression or inhibition of the corresponding enzyme activity by the inhibitor NDGA, a decrease in FaEOBII expression was observed.…”

“…In both climacteric and nonclimacteric fruits, water deficiency generated a rise in ABA content, which accelerated ripening and was accompanied by changes in both metabolites and gene expression (Castellarin et al, 2007;Gong et al, 2010). This dual regulation has also been observed for other genes whose expression is also up-regulated throughout the strawberry fruit-ripening process (Cumplido-Laso et al, 2012;Daminato et al, 2013;Molina-Hidalgo et al, 2013) and molecularly supported both the proposal of PerkinsVeazie (1995) and the findings described by Chai et al (2011), and Medina-Puche et al (2014. This hormonally regulated expression pattern was also similar to that observed for the FaMYB10 gene (MedinaPuche et al, 2014), and it strengthens the relationship between FaMYB10 and FaEOBII.…”

“…et al, 1997; Moyano et al, 1998;Trainotti et al, 1999;Blanco-Portales et al, 2002, 2004Benítez-Burraco et al, 2003;Raab et al, 2006;Griesser et al, 2008;CumplidoLaso et al, 2012;Molina-Hidalgo et al, 2013;MedinaPuche et al, 2014). Besides, the maximum FaEOBII gene expression as well as FaCAD1 and FaEGS2 expression were found in those tissues, such as red-ripened receptacles or petals, where eugenol content was highest (Fig.…”

“…Supplemental Table S5 depicts the primer sequences used for quantitative amplification. Each reaction was performed at least in triplicate, and the corresponding C t values were normalized using the C t value corresponding to an interspacer 26S-18S strawberry RNA gene (Benítez-Burraco et al, 2003;Raab et al, 2006;Encinas-Villarejo et al, 2009;Cumplido-Laso et al, 2012;Molina-Hidalgo et al, 2013). All these values were then used to determine the relative increase or decrease of FaEOBII expression in the samples as compared with those in the control, in accordance with Pedersen (2001).…”

Sugar content analysis and expression profiling of sugar related genes in contrasting Strawberry (Fragaria × ananassa) cultivars

“…Fragaria × ananassa, the cultivated strawberry evolved by hybridization between F. virginiana and F. chiloensis, is globally cultivated fruit crop (Molina-Hidalgo et al 2013;Bestfleisch et al 2014). It is the rich source of health-promoting phytonutrients (e.g., vitamin C, vitamin B-6, niacin, riboflavin, pantothenic acid, vitamin-E and folate, etc.…”