Identification,Evolution And Expression Analysis Of SBP-box Gene In Kiwifruit(Actinidia Spp.)

Kiwifruit is an important global economic crop.However,kiwifruit quality and production have been affected by some abiotic and biotic stresses,such as the majority of currently growing kiwifruit cultivars,like ‘Hongyang',are susceptible to Psa stress.The pathogen can affect the plant at any stage of development causing damping-off,seedling blight,followed by plant death.The release of the kiwifruit genome sequence provides conditions to identify of genes with excellent agronomic traits and resistance at the genome level.The SBP-box genes play crucial roles in plant growth,development,biotic and abiotic stress.Although the genome-wide analysis of SBP-box genes family has been performed in numerous plants,there is remain poorly understood in kiwifruit.In this study,in order to further elucidate the structure and function of genes,the chemical characteristics,gene structures,evolutionary relationships and syntenic analysis of AcSBP genes were investigated.Semi-quantitative technique was used to detect the expression pattern of AcSBP genes in Actinidia chinensis in five different tissues.The expression of AcSBP genes was detected by real-time fluorescence quantitative PCR under different biological and abiotic stresses.We obtained some stress-tolerance genes for further research,providing a basic understanding of the potential important roles of kiwifruit SBP-box transcription factors.The main results are as follows:1.A total of 25 putative kiwifruit SBP-box genes were identified in kiwifruit genome,and named AcSBP1 to AcSBP25 respectively based on their genome location and chromosome orders,nucleotide sequence varied in length from 142-1070 amino acids in aried length,locating on nineteen different chromosomes.2.The Phylogenetic analysis and structure of SBP-box genes in kiwifruit.Based on the analysis of the evolution of the SBP-domain proteins,AcSBP genes were divided into eight subgroups.Gene structure analysis revealed that kiwifruit SBP-box proteins have similar structure from the same group tended to cluster together,which demonstrated that kiwifruit SBP-box genes have been more conserved during plant evolution.3.The duplication events and synteny of kiwifruit and Arbidopsis.Synteny analysis indicated that segmental duplicationhave likely contributed to the expansion and evolution of the AcSBP genes.Sixteen orthologous gene pairs were identified between Arabidopsis thaliana and Actinidia chinensis,these syntenic orthologs likely have similar functions.4.Tissue-specific expression profiles of kiwifruit SBP-box genes was analyzed.Expression analysis of AcSBP genes in five different organs showed that most of the genes were expressed in all tested organs but at different levels.Among 25 predicted genes were expressed in at least three of the five organs.5.Kiwifruit SBP-box genes were responsive to various biotic stress,abotic stress and hormone treatments.AcSBP23 were induced under the GA and MeJA;AcSBP25 were displayed a significant increase under both GA and SA stress;AcSBP13 were showed significant increase under the ETH and MeJA;AcSBP1 and AcSBP3 were showed increase from 1-24 h after NaCl treatment.AcSBP7,AcSBP11,AcSBP15 increased in expression from 48-R48 h under the drought treatment.AcSBP1,AcSBP8,AcSBP13 and AcSBP20 were affected by Psa treatment.