The role of phytohormones in plant cell wall expansion

The cell wall not only provides basic skeleton to plant cell,but also controls the cell size,shape and growth.After mitosis,protoplast enlarges its size through absorbing water.In this phase,the cell wall is remodeled,with cellulose and other new wall materials synthesized and integrated.It finally causes cell growth.Phytohormones,such as IAA,GA,ET and BR,play vital roles in the process of cell expansion,which alters the expression and activity of cell wall-related enzymes such as cellulose synthase A(CESA),expansin(EXP) and xyloglucan endotran glucosylase /hydrolase(XET/XTH),and these factors regulate the cell wall expansion and finally promote cell growth.