| Cotton is an important fiber crop in the world.Colored cotton has natural color,which can meet people’s demand for color textiles without dying.It is economical and environmentally friendly,and has broad development prospects.However,the poor fiber quality and unstable pigment of colored cotton seriously restrict the development of colored cotton.In the face of these problems,we need to strengthen the research on cotton fiber development and pigment formation,and understand the molecular basis of cotton fiber development and pigment formation.In addition,it is more convenient to verify the effects of exogenous additives and related genes on fiber development through in vitro cultures of cotton ovules.We should strengthen the exploration and optimization of ovule culture in vitro.Current studies have shown that cotton fiber is a single cell structure formed by differentiation,elongation of the primary wall and thickening of the secondary wall of the ovule epidermis.The research on the development of colored cotton fiber believes that the elongation of colored cotton fiber is short and the elongation speed is slow,resulting in the short fiber;The early termination of fiber elongation and the short overlap time of secondary wall thickening affected the accumulation of cellulose in cells,leading to thin fibers and poor quality.However,the research on pigment composition of color cotton indicates that pigment formation is mainly regulated by flavonoid metabolism pathway and phenylpropane metabolism pathway.These reports provide a theoretical basis for the study of fiber development and pigment formation of colored cotton.However,as an important signal transduction substance,lipids play an important role in the life activities of cells.Some studies have also shown that the transport and transportation of long-chain fatty acids are necessary for fiber growth,but few studies have studied the regulatory mechanism of lipids in fiber development and color cotton pigment formation.This study used the untargeted lipidomics analysis method with upland cotton white fiber(TM-1)and green fiber(green1-4560),two kinds of cotton material as experimental object,to explore the white fiber elongation period(10 days post anthesis),the overlapping period between elongation period and secondary wall biosynthesis(20 days post anthesis),and the secondary wall biosynthesis(30 and 35 days post anthesis)lipid changes in four fiber development periods,to explore the effect of lipid on white fiber and it provides a reference for the quality improvement of green fiber;the changes of lipid in green fiber after color development(35 days post anthesis)and before color development(30 days post anthesis)were studied to explore the influence of lipid on the formation of pigment in green fiber.In addition,due to the ovule culture is of great significance for studying fiber development,and ovule culture system,the composition of culture medium for ovule development has a great influence,so this experiment by changing the medium factors such as carbon source,KT and Gln,judge the impact of the development of the fibers,in order to build a suitable ovule culture system for TM-1.The main research results are as follows:(1)The results of lipids analysis of white fiber in upland cotton: we compared the lipid changes during white fiber elongation period,the overlapping period between elongation period and secondary wall biosynthesis,and the secondary wall biosynthesis,and found that there were significant differences in lipids at different developmental periods.KEGG enrichment analysis of the different lipids showed that lipids in the glycerophospholipid metabolism pathway may play a role in the fiber elongation period and secondary wall biosynthesis.The lipids in linoleic acid metabolism,alpha-Linolenic acid metabolism and arachidonic acid metabolism mainly play a role in the secondary wall biosynthesis.(2)The results of comparison between the white fiber lipidomics and the green fiber lipidomics: the number of down regulated lipid was 92.1% at 35 days after anthesis compared with 30 days after anthesis in white fiber;the number of up-regulated differential lipids was87.8% at 35 days after anthesis compared with 30 days after anthesis in green fiber.It is speculated that the variation trend of lipid is related to the production of green fiber pigment.The different lipids shared by green fiber and white fiber were excluded,and six lipids DG(36:1),PC(60:1),PS(16:0＿18:3),Bis Me PA(17:0＿18:3),PC(18:0＿14:2),PMe(18:0＿18:3),were screened out,which might have influence on the synthesis of green fiber pigment.(3)The results of ovule culture exploration: the medium with glucose and fructose as carbon source is suitable for TM-1 ovule culture in vitro,the addition of KT to the medium has no significant effect on the fiber growth;adding Gln to the culture medium can change the degree of fiber porosity,make the fiber on ovule more loose,and the fiber is easier to separate,which is beneficial to the identification of fiber properties.By comparing the difference of lipids in different development period of upland cotton white fiber,this topic explored the influence of lipids on fiber development;the difference of lipids before and after the green fiber color change was compared to analyzing the influence of lipids on the formation of pigment.In addition,the system suitable for TM-1 ovule culture was explored,which is of great significance for the study of cotton fiber development,color improvement and in vitro function verification. |
