Kiwifruit SVP2, a dormancy regulator

Abstract

Kiwifruit (Actinidia spp.) are woody perennial vines where bud dormancy and outgrowth affect flower development. MADS-box genes similar to Arabidopsis SHORT VEGETATIVE PHASE (SVP) have been implicated in the regulation of flowering in annual species and in bud dormancy in perennial species. Four kiwifruit SVP-like genes have been identified. Their roles in dormancy and flowering have been analysed in Arabidopsis, tobacco and a high-chill and a low-chill kiwifruit species, Actinidia chinensis var. deliciosa and A. eriantha. Our detailed study of kiwifruit SVP2 that elevated expression of SVP2 suppressed bud outgrowth in the high-chill kiwifruit A. chinensis var. deliciosa. Sufficient winter chilling and the dormancy-breaking agent hydrogen cyanamide (Hi-Cane®) could overcome the SVP2 effect. Transcriptomic analyses of kiwifruit SVP2 transgenic lines suggested that SVP2 mimics the well-documented effect of abscisic acid (ABA) in plant dehydration response.