小麦旗叶衰老与籽粒灌浆成熟同步进行，旗叶过早衰老严重影响小麦产量，而叶绿素降解是叶片衰老的主要标志，解析小麦叶片衰老过程中叶绿素降解途径，对于揭示小麦叶片衰老机制、延缓衰老进程具有十分重要的意义。本项目首先分析二倍体和六倍体普通小麦叶片衰老过程中，叶绿素酶(CLH) 和脱镁叶绿素脱镁叶绿酸水解酶(PPH)的酶活变化和相关基因表达特征；同时克隆小麦脱镁叶绿素脱镁叶绿酸水解酶基因TaPPH, 通过转化拟南芥滞绿突变体pph-1进行功能验证，然后沉默和过量表达二倍体小麦TaPPH基因，再分析RNAi株系和超表达株系叶绿素含量和功能绿叶面积的变化，检测其CLH和PPH酶活变化特征和相关基因表达特征以及与野生型的差异，明确小麦叶片衰老过程中叶绿素酶(CLH) 和脱镁叶绿素脱镁叶绿酸水解酶(PPH)的作用，为实现叶绿素降解的人工控制，选育高产优质小麦品种提供理论基础。

The senescence of flag leaf and grain filling in wheat are synchronous. Premature senescence of flag leaf severely affected on wheat yield. Chlorophyll degradation is the main indicator of leaf senescence. It is of great importance to analyze chlorophyll degradation pathway for exploring the mechanism of the senescence and delaying the aging process in wheat. In the project, the activities of chlorophyllase and pheophytinase and the expression of TaCLH and TaPPH genes will be analyzed during diploid and hexaploid wheat leaf senescence. At the same time, TaPPH gene will be cloned and its function will be verificated by transformation of stay-green mutant pph-1 in Arabidopsis. And then TaPPH gene in diploid wheat will be silenced and overexpressed. The activities of chlorophyllase and pheophytinase and the expression of TaCLH and TaPPH genes in mutent and wild lines will be analyzed again. Based on these results, The function of chlorophyllase and pheophytinase in chlorophyll degradation pathway during wheat leaf senescence will be clear. This will provide theoritical basis for artificially controlling of chlorophyll degradation and breeding high yield wheat varieties.