Comparative analysis of fruit volatiles and related gene expression between the wild strawberry Fragaria pentaphylla and cultivated Fragaria x ananassa

Fragaria pentaphylla, one of several wild strawberry species, produces white or red fruits. The white fruits have a stronger aroma than the red. In this study, solid-phase microextraction was used in combination with gas chromatography-mass spectrometry to compare volatiles during fruit development and maturation from the two fruit types of F. pentaphylla and the cultivated F. x ananassa. A total of 38 volatile compounds were identified in F. x ananassa, while 61 and 53 volatile compounds were identified in the white and red fruits of F. pentaphylla, respectively. The predominant volatiles in white ripe fruits of F. pentaphylla were 3(2H)-furanone 4-methoxy-2,5 methyl (24.71%), butanoic acid, 2-methyl, methyl ester (10.43%), trans-2-hexenal (9.23%). The main volatiles in red ripe fruits of F. pentaphylla were 2-hexenal (21.23%), 1-hexanol (13.29%) and 2-hexen-1-ol acetate (13.00%). While the main volatiles in ripe fruits of F. x ananassa were butanoic acid, ethyl ester (25.80%), 2-hexenal (23.47%) and butanoic acid, 2-methyl (10.09%). In addition, cyclopropane propyl was first found in the white fruits of wild F. pentaphylla at high levels (4.83%). As the intense aroma of the white fruits of F. pentaphylla is characteristic of high 3(2H)-furanone 4-methoxy-2,5 methyl production. RNA-seq was used for quantitative analysis of volatiles-related gene expression. Integrative analysis of GC-MS data and RNA-seq data from fruits of F. pentaphylla indicated that reduction of sugar in red fruits of F. pentaphylla might lead to a relatively lower DMF and higher aldehydes and alcohols compared with that in white fruits.