Response Of Wheat Leaf Cuticle To Drought,Salt And ABA Treatments

The plant cuticle,a hydrophobic extracellular layer that coats the epidermis of aerial organs,widely found on the surface of leaves,flowers,stems,and fruits of plants,is composed of a cutin matrix of ester-linked ?-hydroxylated fatty acids that is covered by epicuticular waxes and infiltrated with intracuticular waxes.Cuticle is the first interface between plants and the environment,so it is the first protective immunity barrier of plants,and it can not only prevent the loss of non-stomatal water and improve the ability of drought resistance,but also keep the plant surface clean,prevent UV,high temperature,high salt,insect pests and other stresses,so play a key role in plant stress resistance.Wheat is one of the main food crops in northern China,and its growth and production have been seriously affected by various natural environment stresses,such as drought,high salt,high temperature,low temperature,ultraviolet radiation and insect pests and so on.As the first protective barrier of plant resistance to stress,the cuticle has become an important focus for many scholars to improve plant resistance.In this study,Jinmai 94 was used as a material,transplanted and cultivated for 11 days after germination,and treated with drought or 150 mM salt and 100 ?M ABA(for 2 days once,6 days in total),The growth and development phenotypes of wheat,such as plant height,leaf yellowing rate,were observed after treatment;The relative biomass of cuticle permeability,such as the relative water content of leaves,rate of the leaves water loss in vitro,and the permeability of chlorophyll,were measured and analyzed;Scanning electron microscope(SEM),semi-thin section and transmission electron microscope(TEM)were also used to observe the ultrastructure of the cuticle of wheat leaves;At last,the relative expression of genes associated with cuticular biosynthesis and the determination of wax content in cuticle were analyzed and compared.The results show that:Compared with the control of wheat seedlings,(1)drought,salt,ABA stress treatment of wheat seedlings have different degrees of dwarf and yellow phenomenon,and the most serious is the wheat under ABA treatment;(2)The relative water content of dry wheat seedlings > the relative water content of salt wheat seedlings > the relative water content of wheat seedlings sprayed by exogenous ABA > the relative water content of the control wheat seedlings,in vitro leaves water loss rate : the control wheat >exogenous spraying ABA wheat > salt wheat > drought wheat,the chlorophyll extracted rate:the control wheat > exogenous spraying ABA wheat > salt wheat > drought wheat,therefore,compared with the above three biomass measurements,the permeability of the cuticle of wheat leaves was as follows: drought > salt > ABA > control;(3)The ultrastructure of cuticle showed that dry cuticle was densest and thickest,wax was the most,barrier and more stronger than salt cuticle and ABA cuticle thickness was third;(4)The wax content in the cuticle: dry wheat > Salt wheat >ABA spraying wheat > control wheat.