中文摘要：

以便解开生物化学的小径并且理解涉及叶老朽的分子的机制，抑制减少性的杂交(SSH ) 被用来产生为在高地棉花的发展老朽子叶表示的抄本差别充实的一个 cDNA 图书馆。在由反向的北污点分析的由基于膜的杂交和随后的证实的微分屏蔽以后，选择了 678 克隆被定序并且分析。这些 cDNA 碎片定序表明 216 个表示顺序标签(EST ) 代表了唯一的基因。这 216 cDNAs， 151 克隆(69.9%) 显示出重要相同到以前已知的基因，当时留下 65 不匹配任何已知的序列。基于他们的通常认为的功能分到 12 个不同范畴的 151 唯一的 ESTsare 由 BLASTanalysis 产生了。这些下垂编码蛋白质是可能的参予大分子降级，滋养的再循环，氧化代谢物的解毒作用，并且发信号并且规章的事件。基因的选择的表示模式用北杂交被证实。Northernhybridization 证实了几个不同模式，从在到老朽症候群的终端阶段的一个很早的阶段的表示。涉及大分子降级和 gluconeogenesis 的克隆编码朊酶和蛋白质，以及压力相关的基因，起来在老朽调整了子叶。

英文摘要：

In order to unravel the biochemical pathways and understand the molecular mechanisms involved in leaf senescence, suppression subtractive hybridization （SSH） was used to generate a cDNA library enriched for transcripts differentially expressed in developmental senescence cotyledons of upland cotton. After differential screening by membranebased hybridization and subsequent confirmation by reverse Northern blot analysis, selected 678 clones were sequenced and analyzed. Sequencing of these cDNA fragments reveals that 216 of expressed sequence tags （ESTs） represented unique genes. Of these 216 cDNAs, 151 clones （69.9%） show significant homologies to previously known genes, while the remaining 65 do not match any known sequences. 151 unique ESTs are assigned to twelve different categories based on their putative functions generated by BLAST analysis. These SAG-encoded proteins are likely to participate in macromolecule degradation, nutrient recycling, detoxification of oxidative metaboUtes, and signaling and regulatory events. The expression pattern of selection of genes was confirmed using northern hybridization. Northern hybridization confirmed several distinct patterns, from expression at a very early stage to the terminal phase of the senescence syndrome. Clones encoding proteases and proteins involved in macromolecule degradation and gluconeogenesis, as well as stress-related genes, are up regulated in senescence cotyledons.