Researchon Resistance Of Cytokinin Biosynthesis Gene:FvIPT And FvLOG In Strawberry

Cytokinins are essential regulators in the different growth processes and environmental responses.At present,genes in Arabidopsis and rice encoding the enzymes responsible for cytokinin biosynthesis such as isopentenyltransferases(IPTs)and Lysine decarboxylases(LOGs)have been characterized,and the model of the cytokinin biosynthesis has been found.Strawberry(Fragaria ananassa Duch)is an important horticultural crop in the world.It contains rich nutrition,and has enormous economic value.The publication of the woodland strawberry(Fragaria vesca)genome sequence provides important data for genome-wide identification of genes related to excellent agronomic traits,stress resistance in strawberry.It is reported that the regulation of genes encoding IPTs and LOGs are essential in response to abiotic stress tolerance in many species.But currently,far less is known about their function in the strawberry.So it is important to study the strawberry IPT and LOG gene families.In our present study,FvIPT genes and FvLOG genes were identified in the strawberry genome by bioinformatics approaches.Phylogenetic analysis,exon/intron structure analysis and biochemical property analysis were performed to investigate and predicted their function and evolution.The expression profiles of FvIPT and FvLOG genes in roots,stems,stolons,leaves,flowers,immature fruits and mature fruits of the strawberry plants were represented using qRT-PCR.At last,expression patterns of FvIPT and FvLOG genes to abiotic stresses and plant hormones treatment were also analyzed in roots and leaves of strawberry,providing a basic understanding of thepotential important roles of FvIPTs and FvLOGs.The main results are as follows:1.By local BLAST,we identified 7 FvIPT genes and 9 FvLOG genes in strawberry.The FvIPT genes were named asFvIPTl to FvLOG7,distributed on chromosomes ?,?,?.Among them,FvIPT2,FvIPT6 and FvIPT7 contained introns.The lengths of CDS varies in length from 882 bp to 2427 bp,the theoretical pI ranged from 4.89 to 8.22,the predicted molecular weights ranged from 33.01 kD to 88.86 kD;The FvLOG genes were named as FvLOG1 to FvLOG9,distributed randomly onchromosomes ?,? and ?,pI ranged from 4.87 to 6.42,the predicted molecular weights ranged from 21.87 kD to 34.49 kD.2.Phylogenetic analysis of strawberry FvIPT and FvLOG proteins along with Arabidopsis and rice counterparts indicated that strawberry FvIPTs and FvLOGs are more closely related to Arabidopsis than to rice,which demonstrated that strawberry and Arabidopsis diverged more recently from a common ancestor of dicotyledons.3.By using phylogenetic analysis,exon/intron structure analysis and biochemical property analysis,7 FvIPT genes could be classified into tRNA-dependent FvIPT genes and ADP/ATP-dependent FvIPT genes;strawberry FvLOG genes are conserved during plant evolution.4.RT-PCR analysis showed that expression patterns of FvIPT genes and FvLOG genes differ in different tissues.5.Expression patterns of strawberry FvIPT and FvLOG genes to abiotic stresses and ABA treatments indicated that under drought stress,5 FvIPT genes and 8 FvLOG genes were down-regulated in roots;3 FvIPT genes were down-regulated in leaves,FvIPT3 gene was up-regulated.Under high temperature stress,FvIPT3 gene was up-regulated in roots and leaves,and FvIPT5 gene was down-regulated in roots and leaves.FvLOG genes were down-regulated under high temperature stress 3 h.The expression of FvIPTl,FvIPT5 and FvIPT6 genes in roots were repressed under high salinity stress,however,in leaves all FvIPT genes were induced after 16 h of high salt treatment;then were up-regulated after 24 h.4 FvLOG genes were up-regulated,2 FvLOG genes were down-regulated in roots under high salinity stress;in leaves 2 FvLOG genes were up-regulated and 2 FvLOG genes were down-regulated.5 FvIPT genes and 9 FvLOG genes were affected by ABA treatment,and were down-regulated in roots.In summary,strawberry FvIPT genes and FvLOG genes play important roles in stress-resistant process.We performed comprehensive analysis of bioinformatics,expression,function and stress-resistance of FvIPT and FvLOG gene families in strawberry,which provided molecular information for accelerating strawberry breedings and improving fruits quality.