Functional Analysis Of The VpYABBY Genes From Chinese Wild Vitis Pesudoreticulata

The establishment of abaxial–adaxial polarity is an important feature of the developmentof lateral organs in plants. Members of the YABBY gene family may be specific to seed-plantspecific transcriptional regulators that play critical roles in promoting abaxial cell fate in themodel eudicot, Arabidopsis thaliana. However, recent study has shown that the roles ofYABBY genes are not conserved in the development of angiosperms. The establishment ofabaxial–adaxial polarity has not been studied in perennial fruit crops. Grapes are an importantfruit crop in many regions of the world. Investigating YABBY genes in grapevines should helpus to discover more about the key genetic and molecular pathways in grapevine development.In this research，two YABBY transcription factor genes were were isolated from Chinese wildV. pseudoreticulata W.T.Wang‘Baihe-35-1’. The expression and function of the two geneswere studied. The main results were as follows:1. Full lengths of the two YABBY genes were cloned from Chinese wild V.pseudoreticulata W.T.Wang‘Baihe-35-1’by using RACE technique based on the ESTsquences, and were designated as VpYABBY1(GenBank accession no. KC139089) andVpYABBY2(GenBank accession no. KC139090). The full-length ORF of VpYABBY1was633bp, encoding a polypeptide of210amino acids, whereas VpYABBY2was555bp, encodinga polypeptide of184amino acids. Phylogenetic analysis showed that VpYABBY1andVpYABBY2belong to FIL and YAB2subfamily, respectively, of the YABBY superfamily.2. Transient expression of VpYABBY1and VpYABBY2showed that both proteins arelocalized in the nucleus of onion epidermal cells and A. thaliana (L. ecotype Col-0)protoplasts by using particle bombardment and PEG transformation respectively.3. Tissue specific expressional analysis revealed that VpYABBY1is expressed strongly inthe young leaves and weakly in the mature leaves of grape, VpYABBY2is expressed in thestems, flowers, tendrils and leaves of grape. To understand the functions of the VpYABBY1and VpYABBY2genes during leaf development, we analyzed their temporal-specificexpression patterns in different developmental stages of the leaves by real-time PCR. Theywere both highly expressed in the youngest leaf and weakly in the most mature leaf. Theirnormalized expressions decreased continuously with leaf development, tending to stability in the latter stages.4. Transgenic Arabidopsis plants ectopically expressing VpYABBY1caused the partialabaxialization of the adaxial epidermises of leaves, behaved similar to those over-expressingFIL or YAB3with abaxialized lateral organs. By contrast, ectopic expression of VpYABBY2inArabidopsis did not cause any alteration in the adaxial–abaxial polarity. VpYABBY1mighthave function in leaf development, while VpYABBY2may play a specific role in carpelsdevelopment and grape berry morphogenesis.