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 membrane- based 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 se- quence tags (ESTs) represented unique genes. Of these 216 cDNAs, 151 clones (69.9%) show signifi- cant 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 gener- ated by BLAST analysis. These SAG-encoded pro- teins are likely to participate in macromolecule deg- radation, nutrient recycling, detoxification of oxidative metabolites, 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 encod- ing proteases and proteins involved in macromole- cule degradation and gluconeogenesis, as well as stress-related genes, are up regulated in senescence cotyledons.
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.
关键词
棉花
衰老
EST
序列分析
育种
基因工程
cotton （Gossypium hirsutum）
senescence
expressed sequence tag （EST）
senescence-associated genes
suppression subtractive hybridization.
作者简介
Correspondence should be addressed to Yu Shuxun （email： yu @cricaas.com.cn
