Genetic Analysis of Strawberry Fruit Aroma and Identification ofO-Methyltransferase FaOMTas the Locus Controlling Natural Variation in Mesifurane Content      

Abstract

Improvement of strawberry (Fragaria 3 ananassa) fruit flavor is an important goal in breeding programs. To investigate genetic factors controlling this complex trait, a strawberry mapping population derived from genotype '1392', selected for its superior flavor, and '232' was profiled for volatile compounds over 4 years by headspace solid phase microextraction coupled to gas chromatography and mass spectrometry. More than 300 volatile compounds were detected, of which 87 were identified by comparison of mass spectrum and retention time to those of pure standards. Parental line '1392' displayed higher volatile levels than '232', and these and many other compounds with similar levels in both parents segregated in the progeny. Cluster analysis grouped the volatiles into distinct chemically related families and revealed a complex metabolic network underlying volatile production in strawberry fruit. Quantitative trait loci (QTL) detection was carried out over 3 years based on a double pseudotestcross strategy. Seventy QTLs covering 48 different volatiles were detected, with several of them being stable over time and mapped as major QTLs. Loci controlling g-decalactone and mesifurane content were mapped as qualitative traits. Using a candidate gene approach we have assigned genes that are likely responsible for several of the QTLs. As a proof of concept we show that one homoeolog of the O-methyltransferase gene (FaOMT) is the locus responsible for the natural variation of mesifurane content. Sequence analysis identified 30 bp in the promoter of this FaOMT homoeolog containing putative binding sites for basic/helix-loop-helix, MYB, and BZIP transcription factors. This polymorphism fully cosegregates with both the presence of mesifurane and the high expression of FaOMT during ripening.

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

“…Fruits can also synthesize volatile phenylpropenes that contribute to their aroma (Jordán et al, 2001;Aubert and Pitrat, 2006;Ortiz-Serrano and Gil, 2010). Eugenol production by ripe strawberry fruits has been reported previously (Pyysalo et al, 1979;Zorrilla-Fontanesi et al, 2012). Interestingly, the amount of this volatile is lower in cultivated fruits (F. ananassa) than in wild diploid Fragaria vesca (Pyysalo et al, 1979).…”

“…It was shown that throughout the strawberry fruitripening process, eugenol accumulates in ripe receptacles (Pyysalo et al, 1979;Zorrilla-Fontanesi et al, 2012;Aragüez et al, 2013). The orthologous gene of FaEOBII in petunia (PhEOBII) has been shown to be involved in eugenol production (Spitzer-Rimon et al, 2010).…”

“…Eugenol is the main phenylpropanoid volatile compound that contributes to strawberry aroma (Pyysalo et al, 1979;Ulrich et al, 1995Ulrich et al, , 2007Zorrilla-Fontanesi et al, 2012). In ripe strawberry fruits, eugenol is biosynthesized by the action of FaEGS2, whose coding gene has a ripening-related expression pattern and presents its maximum expression at the red-ripe stage (Aragüez et al, 2013).…”

Genetic dissection of aroma volatile compounds from the essential oil of peach fruit: QTL analysis and identification of candidate genes using dense SNP maps

“…Improved genotyping capacity (Agarwal et al 2008) and VOC quantification methods (Tholl and Rose 2006) are now enabling the application of quantitative trait loci (QTL) analysis to aroma components. Several studies have addressed the identification of QTLs for VOCs in Rosaceae species as apple (Zini et al 2005;Dunemann et al 2009;Rowan et al 2009a), rose (Spiller et al 2010), and strawberry (Zorrilla-Fontanesi et al 2012) and in other plant species including tomato (SalibaColombani et al 2001;Tadmor et al 2002;Mathieu et al 2009;Zanor et al 2009), grape (Doligez et al 2006), melon (Obando-Ulloa et al 2008), rice (Amarawathi et al 2008), eucalypt (Henery et al 2007; O' Reilly-Wapstra et al 2011), and tobacco (Julio et al 2006). Conversely, no QTLs underlying peach fruit aroma have been reported.…”

“…Of these, about 25 determine the typical peach aroma (Eduardo et al 2010): particularly γ-and δ-decalactone play a key role in association with C 6 compounds, aldehydes, aliphatic alcohols, esters, norisoprenoids, phenylpropanoids, and terpenes (Horvat et al 1990). Key genes associated with aroma production have been described in few plants, including strawberry and apple (Schwab et al 2008;Mathieu et al 2009;Battilana et al 2011;Dunemann et al 2011;Zorrilla-Fontanesi et al 2012), but little is known in peach.…”