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以结球白菜(BrassicarapaL.ssp.pekinensis)结球前期心叶为材料,构建了结球前期球叶cDNA文库,随机挑选克隆单向单次测序后,共得到1162条峰图良好和插入片段长度大于150bp的可用序列。BLASTX及BLASTN序列比对分析表明,94.8%(1102/1162)的表达序列标签(EST)可在蛋白质或核苷酸水平上找到同源类似物。同源性最大的蛋白质按物种来源分析后发现,大约77%的功能已知蛋白质来自拟南芥(Arabidopsisthaliana),另外还有60个EST与已发表的植物基因没有同源性,这一部分EST对于研究结球白菜独特的生理和形态发育途径以及开展基因组分子作图具有重要的意义。同源蛋白质按其功能进行分类表明,参与蛋白质合成过程的酶或蛋白质的EST数量最多,其次是参与能量代谢过程(包括光合作用)的EST序列。在核苷酸水平上,全部EST中只有51%的同源物来自拟南芥。对上述1162条EST进行片段重叠群分析(contiganalysis)共获得895个非冗余片段重叠群,其中723个仅由一个EST组成(即singletons),表明结球白菜结球过程中表达的基因种类繁多。大量EST的获得为进一步了解结球白菜结球机制及获取相关基因提供了重要的序列信息。
In this study, we constructed a cotyledon cDNA library of pre-coccoidal lobes of Brassica rapa L.ssp.pekinensis. One-way single-stranded sequencing of randomly selected clones resulted in 1162 peaks and a length of insert larger than 150bp of available sequence. Alignment of BLASTX and BLASTN sequences showed that 94.8% (1102/1162) of expressed sequence tags (ESTs) could find homologues at the protein or nucleotide level. The most homologous protein analyzed by species source found that about 77% of the functions of the protein are known from Arabidopsis (Arabidopsisthaliana), an additional 60 ESTs have no homology with published plant genes, this part of the EST for It is of great significance to study the unique physiological and morphological developmental pathways of cabbage and to carry out the molecular mapping of the genome. Classification of homologous proteins by their function indicates that ESTs involved in protein synthesis process have the largest number of ESTs and secondly ESTs involved in energy metabolism processes including photosynthesis. At the nucleotide level, only 51% of all ESTs are from Arabidopsis thaliana. A total of 895 non-redundant fragment contigs were obtained from the above 1162 ESTs, of which 723 were composed of only one EST (singletons), indicating that there are many genes expressed during the process of node heading . The availability of a large number of ESTs provided important sequence information for further understanding of the mechanism of node-bearing in cabbage and access to related genes.