Function Analyses Of Cellulose Synthase And Cellulose Synthase-like Genes D Families In Arabidopsis

Plant cell walls decide plant cell size and shape,provide strength support and dynamic protection in plants.Hence,understanding of mechanisms that link cell proliferation and cell wall integration is an important discipline in developmental biology that was largely unexplored.Because cellulose is the prominent component of plant cell walls,cellulose synthesis is central to plant morphogenesis and growth.However,regulatory aspects of cellulose synthesis are poorly defined.Although the Ces A family have a wide range of genes with diverse biological functions,genetic manipulation of the family to enhance plant growth and lignocellulose production has proved difficult.Thus,exploring the Ces As specific functions and their potential genetic manipulation model to improve cellulose synthesis is benefit to biomass production.In this study,we initially selected dozen of transgenic Arabidopsis plants that respectively over-expressed or co-over-expressed representative AtCesAs and CSLD3 genes,and also generated distinct genetic AtCesA mutants.We then performed an integrative analysis among the transgenic plants and mutants,and investigated their distinct functions in cellulose synthesis and plant cell wall formation,cell elongation and division,plant growth and biomass production.The main results of this study are described below:1.Based on comparative analyses of transgenic plants that respectively overexpressed or co-overexpressed six AtCesAs(CesA2,A5,A6,A3,A7,A9)genes and four AtCesAs mutants(rsw1/Ces A1,prc1-1,CesA6,IRX3/CesA7),this study summarized three distinct models linked cellulose synthesis,plant cell wall formation,plant cell growth and biomass production:(i)Primary cell wall enhancement model,(ii)Primary cell wall regulation model and(iii)Secondary cell wall determination model.In the first model,three primary wall AtCesA6-like genes(CesA2,A5,A6),but not CesA3/CesA9 and secondary wall CesA7,could enhance cellulose synthesis in vivo and alter microfibrils characteristics in vitro in primary cell walls,due to an increase in cellulose synthases particle movements on plasma membranes in living cells,which positively regulated cell elongation and division to promote young plant growth.In the second model,primary cell wall synthesis dynamically regulated secondary cell wall deposition,which affected plant cell wall integrity.In the third model,plant cell wall integrity and secondary wall thickness predominately determined mechanical strength and biomass production in mature plants.Hence,this study demonstrated three AtCesA6-like genes unique functions in plant biomass production improvement and proposed new ideas to promote plant growth and development by enhancing primary wall synthesis firstly and then positively affecting the secondary wall synthesis,which provides a theoretical basis for genetic improvement of plants.2.As CSLD gene family show the highest sequence similarity to Ces As among cellulose synthase like(CSL)families,we overexpressed genes of CSLD and CesA families in context of CSLDs and CesAs mutants and did functional analyses of some lines.The data support that CSLD3 could play partial CesA role in cellulose biosynthesis during certain periods in particular tissues.In addition,this study investigated CSLD3 gene functions in plant cell elongation,root hair development and plant growth by using transgenic Arabidopsis plants that respectively overexpressed At CSLD3 and cotton Gh CSLD3 genes and distinct ethylene response mutants.The date explored CSLD3 roles in root hair tip growth and cell elongation regulated by ethylene and phosphate starvation signling pathways.