Analysis Of Fiber Pigment Composition And PKS Genome In Brown Cotton

Compared with white cotton,brown cotton has unstable fiber color,easy decomposition,and irregular pigmentation.Therefore,understanding the chemical nature and synthesis pathway of brown pigment is an important basis for brown cotton research,in order to provide a theoretical basis for further study on the synthesis mechanism of brown cotton pigment.In this experiment,cotton bolls from different periods of brown cotton were used as the research object(white cotton as control),and the dynamic changes of pigment precursor accumulation in brown cotton during cotton fiber development were analyzed.At the same time,the PKS gene of upland cotton was studied by bioinformatics.Whole genome identification screening.The aim is to provide a theoretical basis for clarifying the synthetic pathway of pigments.The research results are as follows:(1)The total anthocyanin content of brown cotton and white cotton showed a trend from high to low during the development of cotton boll.The content of brown cotton total anthocyanins decreased sharply after 30 DA A,and the downward trend was significantly faster than that of white cotton.At the same time,40 DAA did not find anthocyanin in brown cotton and white cotton seed coat and fiber.It indicated that the synthesis and accumulation of brown cotton pigment had nothing to do with the variation of anthocyanin content.(2)The total flavonoid content of brown cotton seed coats increased at 10～15 DAA,which may be related to the precursors of synthetic pigments.The content of total flavonoids in brown cotton fiber increased from 15 to 30 DAA,indicating that a large amount of pigment matter accumulated during this period.From the change law of phenolic substances in cotton boll development period,20～30 DAA,the total phenolic content in white cotton fiber increased,and the total phenol content in brown cotton decreased.The possible reason is that the synthesis of brown pigment consumes part of pigment precursor material.(3)According to the picture of the in vitro oxidized fiber during the development of brown cotton,the isolated fiber placed in the air during development has a darker color as the oxidation time increases.The white cotton fiber color did not change significantly,maintaining a white color,which may be in white cotton fiber,and there is a certain difference between the phenolic substance and the brown cotton fiber.At the same time,it can be seen that the change in color of the developed brown cotton fiber placed in oxygen is not significantly greater than that in the developmental brown cotton fiber placed in the air.The color change of the brown cotton fiber during development in nitrogen was less pronounced.This suggests that in the process of oxidation of the precursor of brown pigment,condensed tannin,in addition to contact with oxygen,there are other factors that affect the synthesis of brown pigment.(4)The monomeric catechins are the same in both the white cotton and the brown cotton seed coat,which is consistent with the same color of the brown cotton seed coat and the white cotton seed coat.Moreover,the monomeric catechins in the brown cotton fibers were the same as those in the seed coats,and only the monomeric catechins in the white cotton fibers were found to be different,and the catechin content in the white cotton fibers was the largest.Therefore,there may be differences in the size and monomer composition of the condensed tannin polymer due to the difference in the content of each monomeric catechin in the brown cotton and the white cotton,and finally the color difference between the brown cotton fiber and the white cotton fiber is caused.(5)Eleven PKS genes were identified at the whole genome level of Upland cotton,and comparative genomic analysis was performed with PKS genes in poplar,grape,apple,and Arabidopsis.Bioinformatics analysis showed that the expression pattern of GhPKS5 was basically consistent with the accumulation of proanthocyanidins in brown cotton fibers.At the same time,GhPKS5 is mainly expressed in brown cotton fiber and expressed in trace amounts in other tissues of brown cotton.It is speculated that GhPKS5 is closely related to the biosynthesis of brown cotton proanthocyanidins.