Effects Of Endogenous And Exogenous ABA On The Development,Cutin And Wax Of Rice Anther

Rice is one of the most important agricultural crops.It is important to improve the yield of rice for addressing the global food crisis.Male reproductive development is an essentialprocess for flowering plants and crop seed production.Butenvironmental effects or genetic mutationswill lead to defective anther development and pollen fertilityfrequently.Then,the yield of ricedeclined seriously.Abscisci acid(ABA)is now recognized as one of the five major plant hormones.ABA play a important role in abiotic stress and biotic stress,such as promoted seed maturation and dormancy,stomatal closure,dehydration tolerance,leaf senescence,seed dormancy andmaturation,and coordinated growth of roots and shoots.Cuticle is a layer of fatty substances which coversthe outer surface of aerial plant tissues.It restricts non-stomatalwater loss,protects plants against ultraviolet radiation and reduces water retention onthe surface of the plant thus minimizing deposition of dust,pollen and air pollutants.Inaddition,surface wax is believed to play important roles in plant defense against bacterial andfungal pathogens.Previous studies have shown that the cuticleplays an important role in plant reproductive development.ABA affects the synthesis and transcriptionof a large number of genes in waxy synthesis in plant.In our study,we investigated that whether the content and chemical composition of cuticular waxes will change by the exogenous application of abscisic acid(ABA)and endogenous application of abscisic acid(ABA).Three kinds of rice zhonghua10(WT),L4 obtained from the progeny of japonica rice variety ‘Zhonghua10’ transformed with plasma pCAMBIA/Ubi:AtNCED3,Y which applied the exogenous abscisic acid(ABA)in zhonghua10,were used to test the effect of endogenous and exogenous abscisic acid(ABA)on cuticular wax amount and composition.Compared with the wild type(WT),the L4 were significantly decreased in plant height.Meanwhile,as for flower time,L4 delayed about 10-15 days compare with WT.The color ofthe flowers and anthers of three kind of rice do not change significantly.But the anther length of Y is significantly shorter.We noted reduced cell length in the Y anther epidermis compared with the wild type by scanning electron microscopy examination.The wax content of Y anther surface increased,and the wax content of L4 anther surface decreased.Anther surface analysis of cutin composition show that the content of C22:0 and C24:0 2-hydroxy straight chain fatty acids increase significantly,the content of C18:2 and C18:3 fatty acid increased..Then the content of C20:0 2-hydroxy straight chain fatty increase significantly.The analysis of wax show that the content of the alkane increased,but the content of the fatty acid and the steroid decreased in L4.On the contrary,the content of the alkane decreased,but the content of the fatty acid increased in Y.Besides,the content of beta-sitosterol increased.The observation of anthers in a thin slice at different times show that the thickness of tapetum cell increased compare with WT and Y at 10 stage.But,the tapetal cells of L4 completely disappeared at 12 stage compared with WT and Y,the tapetal cells of WT and Y disappear gradually.The expression of rice gene related to the biosynthesis of cutin and wax changed,after the content of endogenous and exogenous ABA increased.The expression of DTD,UDT1,EAT1,OsC4 and RTS increased in Y,after the content of exogenous ABA increased.The expression of UDT1,EAT1 and RTS increased in L4,after the content of ABA endogenous increased.