Research On Cotton Fiber Development And Proteome Of Xinluzao 36 And Xinhai22

Cotton fiber development transition from elongation to secondary cell wall biosynthesis is a critical growth shifting phase that affects cotton fiber final length,strength and other properties.Morphological dynamic analysis indicates that an asynchronous fiber developmental pattern between two cotton species Gossypium hirsutum cv Xinluzao 36 and G.barbadense cv Xinhai 22.The critical time point in Xinluzao 36 and Xinhai 22 fiber elongation termination is,respectively,23 and 27 days post-anthesis(DPA).The temporal changes of protein expression at three representative development periods(15-19,19-23,23-27 DPA)were examined in both species with iTRAQ technics.Strikingly,a large proportion of differentially expressed proteins(DEPs)was identified at 19-23 DPA in Xinluzao 36 or at 23-27 DPA in Xinhai 22,corresponding to their fiber developmental transition timing from elongation to secondary cell wall biosynthesis.Furthermore,fourier transform infrared(FTIR)spectroscopy analysis showed that with the development of cotton fiber,the main differences in the biochemical components of cell wall between Xinluzao 36 and Xinhai 22 were in 20 DPA.The most of the differential absorption peaks at 20 DPA were higher than previous and subsequent developmental stages,especially the absorption peak at 3000-2800 cm-1(with the structure of-CH3 and-CH2),1800-1500 cm-1(the protein structure region of amide ? and amide ?),1500-1100 cm-1(Structural domains of phenylpropanoids),respectively.The result further determined the differences in fiber wall development between the two cotton fibers was about in 20 DPA.To better understand fibers transitional development,we comparatively analyzed those DEPs in 19-23 DPA of Xinluzao 36 vs.in 23-27 DPA of Xinhai 22,and noted that these cotton species indeed share fundamentally similar fiber development features under the biological processes.It also showed that there have limited overlaps in both specific upregulated and downregulated proteins between the two species,suggesting specie-specific protein regulations in development.Proteomic profiling revealed dynamic changes of several key proteins and biological processes that potentially correlate with fiber development transition.During the transition,upregulated proteins mainly involved in carbohydrate/energy metabolism,oxidation-reduction,cytoskeleton,protein turnover,Ca2+ signaling etc,whereas important downregulated proteins mostly concentrated in phenylpropanoid and flavonoid secondary metabolism pathways.Several changed proteins in this key stage were also validated by qRT-PCR.Overall,the present study provides accurate pictures of the regulatory networks of functional proteins during the fiber developmental transition.