Identification of genes associated with cotyledon senescence in upland cotton.pdfVIP

ARTICLES 1085 Chinese Science Bulletin 2006 Vol. 51 No. 9 1085—1094 DOI: 10.1007/s11434-006-1085-5 Identification of genes associated with cotyledon senescence in upland cotton SHEN Fafu1,2, YU Shuxun2, XIE Qingen1, HAN Xiulan1 FAN Shuli2 1. Key Laboratory of Shangdong Province for Crop Biology, College of Agronomy, Shandong Agricultural University, Taian 271018, China; 2. Cotton Research Institute, Chinese Agricultural Academy of Sciences, Anyang 455112, China Correspondence should be addressed to Yu Shuxun (email: yu@) Received December 1, 2005; accepted February 14, 2006 Abstract 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 degr