The Preliminary Study Of Anthocyanin Metabolism And GhCHS,GhANR And GhLAR In Leaf Color Mutants Of Gossypium Hirsutum L.

The reasons for the plant leaf coloring are very complicated.The proportion and distribution of anthocyanins,chlorophyll and carotenoids in leaves directly affect the color of leaves.Anthocyanin is one of the main pigments in colorful leaves and fruits.Many factors affect anthocyanin accumulation and pigmentation in plants.The study of anthocyanin biosynthesis pathways and regulatory factors is the focus and hotspot of color formation in leaves,fruits and vegetables.While,there are few studies on the mechanism of leaf color mutation and fiber color formation in cotton as one of the important economic crops.And the color of the leaves of most cotton varneties/lines is green,and the fibers color is white.It plays an important role in fiber color improving to study the coloration mechanism in cotton leaf color mutants.1.The relationship between leaf or fiber color and anthocyanin metabolism in 21 cotton leaf color mutants was studied.The anthocyanin content in the leaves of 21 leaf color mutants were measured,and the results showed that the anthocyanin extracts from red or purple leaves were significantly darker than those from non-red or purple leaf mutants.The analysis of anthocyanin content in the 15-day fibers of cotton leaf color mutant showed that the higher the accumulation and content of anthocyanin,the deeper the color of cotton fibers.The results showed that the changes of anthocyanin content in leaves and fibers were not consistent.In order to better study the coloration mechanism of leaves and fibers in the upland cotton,a total of 8 cotton leaf color mutants were selected for the follow-up experiments according to the leaves anthocyanin content of the "high-medium-low" level.2,The anthocyanin synthase gene(GhCHS),two transportase genes in the anthocyanin synthesis pathway(GhLAR and GhANR)were studied.The results of the phylogenetic tree from the cotton CHS family indicated that LOCI07914136 was a separate branch and far away from other members.The physical and chemical properties of the primary structure of upland cotton showed that among the 15 copies of CHS,except LOC107914136,the isoelectric point was 7.11,and the others were less than 7.Bioinformatics analysis including homology analysis,evolutionary tree construction,physical and chemical properties,transmembrane domains and tertiary structure modeling showed that GhCHS,GhLAR and GhANR genes were highly homologous and conservative.In order to analyze their functions,the conserved regions of the three genes were then used as the target regions for gene interference.3.The expression levels of GhCHS,GhANR and GhLAR genes were analyzed in leaves and fibers in different developmental stages of the cotton leaf mutants.In white and green variegated leaves,the expression levels of the three genes were low,but increased significantly in purple leaves mutants.In different developmental stages of the fibers,all of the three genes were highly significantly expressed in the brown fiber of zihua mutant.The results indicated that the three anthocyanin pathway synthesis and transport enzymes played an important role in the formation of brown fiber color.4.The interfering expression vectors of cotton GhANR,GhLAR and GhCHS genes were constructed.A large number of colored cotton of ZX1 transgenic interfered plants were obtained by virus induced gene silencing.The expression levels of GhANR,GhLAR and GhCHS genes in different developmental stages of GhCHSi,GhANRi and GhLARi lines were detected.Compared with the controls,the gene expression of each interfered line was significantly decreased.The anthocyanin content were measured and analyzed in young leaves,fiber seed coat mixture and cotton kernels of transgenic interfered plants and control plants.The results showed that the anthocyanin content in young leaves and fibers of GhANRi,GhLARi and GhCHSi were significantly lower than that in the control plants.Through the comparison of the fiber color,target gene expression level and anthocyanin content of RNAi and control lines,we found that the lower the gene expression level,the lower the anthocyanin content,and the lighter the fiber color.The results indicated that GhANR,GhLAR and GhCHS genes played an important role in anthocyanin synthesis and accumulation in fibers,which influenced the color rendering of fibers.This study provided a foundation for further research on the mechanism of cotton leaf and fiber coloration and cultivation of more cotton varieties with multi-color fibers.