Abstract

The raffinose synthetase (RFS) and galactinol synthase (GolS) are two critical enzymes for raffinose biosynthesis, which play an important role in modulating plant growth and in response to a variety of biotic or abiotic stresses. Here, we comprehensively analyzed theRFSandGolSgene families and their involvement in abiotic and biotic stresses responses at the genome-wide scale in kiwifruit. A total of 22GolSand 24RFSgenes were identified inActinidia chinensisandActinidia erianthagenomes. Phylogenetic analysis showed that theGolSandRFSgenes were clustered into four and six groups, respectively. Transcriptomic analysis revealed that abiotic stresses strongly induced some crucial genes members includingAcGolS1/2/4/8andAcRFS2/4/8/11and their expression levels were further confirmed by qRT-PCR. The GUS staining ofAcRFS4Pro::GUS transgenic plants revealed that the transcriptionlevel ofAcRFS4was significantly increased by salt stress. Overexpression ofAcRFS4inArabidopsisdemonstrated that this gene enhanced the raffinose accumulation and the tolerance to salt stress. The co-expression networks analysis of hub transcription factors targeting keyAcRFS4genes indicated that there was a strong correlation betweenAcNAC30andAcRFS4expression under salt stress. Furthermore, the yeast one-hybrid assays showed thatAcNAC30could bind theAcRFS4promoter directly. These results may provide insights into the evolutionary and functional mechanisms ofGolSandRFSgenes in kiwifruit.Keywords:kiwifruit;galactinol synthase;raffinose synthetase;gene family;abiotic and biotic stresses