Grape SISTER OF RAMOSA3 is a negative regulator of pedicel development of grape inflorescence

Abstract

We report here the relationship between pedicel development and grape SISTER OF RAMOSA3 (VvSRA) expression in grapevine. The increase in VvSRA expression, but not grape RAMOSA3 expression, in young grape inflorescence decreased the number of pedicels on the lateral branch of grape inflorescence. This suggests that VvSRA negatively regulates pedicel development on the lateral branch of grape inflorescence, thereby decreasing berry number on a bunch in cultivars expressing VvSRA abundantly. Similarly, VvSRA overexpression decreased the number of flower buds on secondary branch in Arabidopsis plants. In addition, VvSRA overexpression had notable effects on Arabidopsis plant phenotypes, such as smaller flowers, shorter inflorescence, and expanded rosette leaves. As VvSRA encodes a trehalose 6-phosphate phosphatase, VvSRA overexpression might decrease trehalose 6-phosphate in the transgenic Arabidopsis plants, thereby causing the phenotypical alternations. These findings may provide new information on grapevine morphogenesis including pedicel development by SISTER OF RAMOSA3 and trehalose metabolism.