The Preliminary Function Analysis Of UDP-N-acetylglucosamine Pyrophosphorylase 1 And 2 Genes In The Process Of Rice Leaf Senescence

Various factors influence leaf senescence in rice.UDP-N-acetylglucosamine pyrophosphorylase 1 gene,named as UAP1,which mutation deactivation results in the early leaf senescence phenotype in rice.Therefore,the relationship between UAP1 gene and the rice leaf senescence is speculated:UAP1 gene may have a negative regulatory role on rice leaf senescence and play an indispensable role in rice growth and development.In rice genome,there is also a highly homologous gene UAP2.Many molecular methods,eg.the fluorescence quantitative PCR(qRT-PCR),were used to analyze expressions of UAP1 and UAP2 genes and the protein glycosylation in the process of rice leaf senescence.The results of this study were as follows:1.UAP1 and UAP2 genes had no negative regulatory role in the leaf senescence process,UAP1 gene was essential to the growth and development of rice,and UAP2 gene played a role in the early development of rice.Firstly,the expression levels of UAP1 and UAP2 genes in the leaves of Zhonghua 11(ZH11)were analyzed by qRT-PCR.The results showed that the expression of UAP1 gene was very high in the whole process of growth and development of rice,and was up-regulated in the process of senescence.The expression levels of UAP2 gene tended to be higher in young leaf period,and were lower and no significant differences in the process of senescence.Next,a japonica cultivar ZH11 and an indica rice cultivar 9311 were senescence-induced with dark treatmenton.The results showed that the expression levels of UAP1 and UAP2 gene in the treatment group were higher than those in the control group for them.2.The over-expression of UAP1 gene did not delay the appearance of leaf senescence.UAP1 gene mutation inactivation leads to rice leaf senescence.Can the overexpression of UAP1 gene delay leaf senescence?The transgenic plants with UAP1 gene overexpression were obtained,investigated their phenotype.The growth phenotypes of the transgenic T1 plants and control were no significant differences in the field.Transgenic overexpression plants and control plants had withered death symptoms,when they were senescence-induced with dark treatmenton.3.The changes in glycosylation of proteins were likely to be involved in leaf senescence in rice.The UAP1 gene encodes UDP-N-acetylglucosamine pyrophosphorylase,which is involved in the formation of UDP-N-GlcNAC,and UDP-N-GlcNAC participates in the protein glycosylation with GlcNAC residues.In this study,the glycosylation levels of total leaf protein were analyzed by Western blot for wild-type ZH11 and UAP1 mutant spl29.The results showed that the level of spl29 mutant glycosylation was higher than that of wild-type,and the increases of protein glycosylation were detected during the natural leaf senescence and dark induced leaf senescence.