Genome-wide Identification Of Fucosyltransferase(FucT) Gene Family And Functional Analysis Of FucT4 In Cotton

Cotton is the most important source of textile fiber in the world and is of great economic value.Numerous genes participate in cotton fiber development.Understanding the function of these genes is fundamental and meaningful for improving cotton fiber quality in breeding system.Ligon lintelss(Lil)is a short fiber mutant strain discovered in 1930s.The mutant is stunting and the leaves and stems are distorted.Based on the microarray data of 10 DPA fibers from wide type lillil and mutant Lillil,we found an EST sequence which exhibited positive correlation with fiber elongation(EST number:G070B08A).The completed CDS sequence of the gene was obtained via BLAST and electronic cloning.Sequence alignment showed that this gene shared 69%identities with AtFUT13,a reported a 1,3/4-fucosyltransferase.As no report was found about this gene,we named this gene as GhFucT.Based on the genomic sequence information of Upland cotton G.hirsutum TM-1,we identified the FucT gene family in cotton.Sequence analysis revealed that GhFucT isolated in microarray data is homolocgous to GhFucT4 identified in the genome identification.Phylogenetic analysis,transcriptone analysis,qRT-PCR analysis and fiber quality correlation analysis demonstrated that GhFucT4 gene is important for fiber development.Furthermore,we verified the function of GhFucT4 gene in cell elongation via ectopic expression in Arabidopsis thaliatia.All the experimental results are as follows.1.Eight FucT genes were identified in tetraploid cotton G hiirsutum,with four genes in At-subgenome and four in Dt-subgenome,distributed on six chromosomes.Clustering and phylogenetic analysis showed that the FucT genes were divided into two groups.Group I includes GhFucT1 to GhFucT3,and Group II only includes GhFucT4.2.The expression pattern of FucT genes in various tissues of G.hirsutum was investigated by transcriptome analysis.It was found that the expression of the FucT genes is quite different in different tissues,organs and developmental ovules and fibers.GhFucT1 and GhFucT3 genes have very low expression level in all the tissues examined;GhFucT2 gene is highly expressed in cotton leaves,but is very low in other tissues;GhFucT4 gene is lower expressed in stems,leaves and 0 DPA ovules,but is highly expressed in roots and developmental cotton fibers.qRT-PCR analysis also showed that GhFucT4 gene is preferentially expressed in cotton fibers and the expression of FucT4 is higher in G.barbadence fibers than that in G.hirsutum.We conducted fiber quality correlation analysis.The results exhibited that GhFucT4 gene is significantly correlated with fiber length,strength and fiber percentage of cotton seed.These results demonstrated that FucT4 gene is important for cotton fiber development and quality formation.3.The function of FucT4 gene in cell elongation was verified via ectopic expression of GbFuc4 gene in Arabidopsis thaliana.We cloned GbFucT4 sequence into the bionaryvector and transferred it into wild type Arabidopsis and several positive transgenic strains were obtained.We find that the primary roots were significantly elongated in GbFucT4 over-expressed Arabidopsis lines.Further analysis showed that the primary roots cells of transgenic plants were longer than that in WT.The result indicates that the a 1,3/4-fucosyltransferase FucT4 has an important role in plant cell elongation.Based on the above analysis,we demonstrated that the cotton FucT4 gene could be the primary FucT gene involved in fiber development.This gene plays important functions in fiber development and quality formation process.