VcFAS, VcSUN and VcOVATE orchestrated the fruit morphogenesis in southern highbush blueberry during the pre-anthesis and fruit development

Abstract

Abstract Fruit morphology is an important trait closely related to fruit quality and quality parameters evaluated for new cultivar breeding. FASCIATED (FAS), SUN and OVATE are characterized as key genes that regulate fruit morphology in tomato and other fruits, however, its underlying mechanism driving variation in blueberry is not known. In this study, FAS, SUN and OVATE genes were isolated from southern highbush blueberry ‘O’Neal’ (10–14 locules) and ‘Bluerain’ (10 locules). VcFAS and VcSUN gDNAs contained 5 introns and 4 exons, whereas no intron was detected in the VcOVATE gDNAs. Additionally, between two cultivars, long-fragment insertions/deletions (in/dels) were found in the 1st, 2nd and 5th introns of VcFAS and in the 2nd introns of VcSUN gDNAs. The expression levels of VcFAS, VcSUN and VcOVATE were significantly higher in the expanded leaves and lower in the rootlets than those in the stems. VcFAS and VcSUN mRNAs in the ‘Bluerain’ flower buds were dramatically higher than in those of ‘O’Neal’, and partially lower in the ‘Bluerain’ fruits than in those of ‘O’Neal’. Compared with VcFAS and VcSUN, VcOVATE transcripts were relatively low throughout the flower bud and fruit development, although the VcOVATE transcripts were somewhat higher in the early flower bud and fruit stages of ‘Bluerain’ than in those of ‘O’Neal’. The results indicated that VcFAS, VcSUN and VcOVATE might influence blueberry fruit morphology at pre-anthesis and post-pollination stages, but particularly at the pre-anthesis stages, and the in/dels of VcFAS and VcSUN introns might affect fruit shape and size through regulating the locule number during flower bud enlargement.