VvPL15 Is the Core Member of the Pectate Lyase Gene Family Involved in Grape Berries Ripening and Softening

Abstract

The process of ripening and softening in grape begins at veraison and is closely related to the depolymerization of pectin components. A variety of enzymes are involved in pectin metabolism and one class of enzyme, pectin lyases (PLs), have been reported to play an important role in softening in many fruits; however, little information is available on the <i>VvPL</i> gene family in grape. In this study, 16 <i>VvPL</i> genes were identified in the grape genome using bioinformatics methods. Among them, <i>VvPL5</i>, <i>VvPL9</i>, and <i>VvPL15</i> had the highest expression levels during grape ripening, which suggests that these genes are involved in grape ripening and softening. Furthermore, overexpression of <i>VvPL15</i> affects the contents of water-soluble pectin (WSP) and acid-soluble pectin (ASP) in the leaves of Arabidopsis and significantly changes the growth of Arabidopsis plants. The relationship between <i>VvPL15</i> and pectin content was further determined by antisense expression of <i>VvPL15</i>. In addition, we also studied the effect of <i>VvPL15</i> on fruit in transgenic tomato plants, which showed that <i>VvPL15</i> accelerated fruit ripening and softening. Our results indicate that <i>VvPL15</i> plays an important role in grape berry softening during ripening by depolymerizing pectin.