Genome-wide Identification Of HSP20 And SOD Gene Family In Grape And Expression Profile During Berry Development

Superoxide dismutase（SOD）is an important family of genes encoding SOD proteins,which is the front line of plant antioxidant systems.Fruit maturation were supposed to be an oxidative process,Reactive oxygen species（ROS）played an important role in fruit ripening process.Small heat-shock protein（s HSP or HSP20）,as a chaperone protein,which can prevent damage to the protein caused by enviro nmental stress and help them to fold or degrade.It plays an important role in plant growth and development,including various development processes,such as embryos occurrence,seed germination and fruit maturity.The previous research results identified SOD and HSP20 of grape as different genes related to fruit development.To analyze the key members of the SOD and HSP20 families that may play an important role in the early maturing of grapes,two gene family analyses were performed.The main results are as follows:1.Based on the bioinformatics methods,13 VvSOD genes were identified from the grape genome sequence.Phylogenetic analysis indicates that these VvSODs can be divided into two groups.The Vv Cu/Zn SOD1a and Vv Cu/Zn SOD1c genes were identified as tandem replication genes.According to the expression analysis of RNA-Seq and q RT-PCR results in‘Kyoho’and its early-mature bud mutant‘Fengzao’,the Vv Cu/Zn SOD1c gene was involved in grape fruit maturation and it was the main candidate genes.Sequence a nalysis of the Vv Cu/Zn SOD1c gene in‘Fengzao’showed that the coding sequence was consistent with‘Kyoho’.According to bioinformatics and expression analysis,the VvSOD gene may be involved in the ripening process of grape fruits,and Vv Cu/Zn SOD1c is the main candidate gene to further explore its potential role in the‘Fengzao’ripening process.2.A total of 48 VvHSP20 genes were identified from the grape genome.According to phylogenetic analysis and subcellular localization,the 48 VvHSP20genes were divided into 11 subfamilies（CI,CII,C III,CV,C VI,C VII,MI,MII,ER,CP,and PX/Po）.Further structural analysis showed that most of the VvHSP20（93.8%）genes had no introns or only one intron,while genes clustered together based on phylogenetic trees had similar motifs and evolutionarily conserved structures.HSP20s contain a conservedα-crystallin domain（ACD）.In addition,48 VvHSP20 genes are distributed on 12 grape chromosomes,and most of the VvHSP20 genes are located near or distal to the chromosome.C hromosomal mapping revealed that four groups of VvHSP20 genes were tandem repeat genes.By analyzing the cis-regulatory elements of VvHSP20s,Phytohormone responsive,abiotic and biotic stress-responsive,and plant development-related cis-elements were determined.The expression profile of VvHSP20s gene（VvHSP20-1,11,14,17,18,19,20,24,25,28,31,39,42,43）were largely similar between RNA-Seq and q RT-PCR analysis after H₂O₂ treatment.The results showed that most VvHSP20s were down-regulated after H₂O₂ treatment during fruit development.The VvHSP20s gene does participate in grape fruit development,and the difference in its transcriptional level may be the result of functional differentiation during evolution.3.Gene cloning and sequence analysis.According to the gene family analysis and expression analysis of SOD and HSP20 in grape,we selected the differentially expressed genes of the two families in grape development.We selected two SOD genes（Vv Cu/Zn SOD1a and Vv Cu/Zn SOD1c）and four HSP20 genes（Vvhsp20-17,Vvhsp20-19,Vvhsp20-31 and Vvhsp20-43）for full-length coding sequence cloning,and further compared them with other species.The results showed that there was little difference in sequence between them and other species,which further verified the results of our bioinformatics analysis.It has a certain reference value for future research on the functional characteristics of grape VvHSP20 and VvSOD genes.