禾谷类植物淀粉合成关键酶的鉴定与比较分析
毕业论文关键词：禾谷类植物；淀粉；关键酶；同源基因；适应性进化
Molecular Characterization and Comparative Analysis of the Genes Encoding Key Enzymes of Starch Biosynthesis in Cereal Plants
Abstract: Starch is the main source of carbon storage in the organisms, there are many key enzymes of the synthesis pathway , and most of them are in the form of multi gene. In this study, the key enzyme protein sequences of Arabidopsis starch synthesis as probes, 67 starch biosynthesis key enzymes genes were excavated from cereal plant, and the sequence, expression and evolution were analyzed. Phylogenetic analysis showed that 67 genes were pided into 6 major groups, the subgroup had many gene duplication events, and the gene was easily duplicated and the gene was lost or duplicated. Sequence Analysis showed that the genetic structure, conserved motifs and functional domains of the same group showed high conservatism between different groups of sequence features great variation. Expression analysis revealed that expression of starch synthase gene in different tissues and plants at different growth stages have obvious differences, which may related to gene function specific and tissue specific. These results provide the help to the biological function of key enzymes in the synthesis of cereal starch.
Key words: Cereal Plants, Starch, Key Enzymes, Homologous Genes, Adaptive Evolution
目 录
摘 要 2
引言 3
1 数据与方法 4
1.1 物种选择与基因检索 4
1.2 序列比对与聚类分析 4
1.3 蛋白序列特征分析 4
1.4 同源基因对的选择压力检测 5
1.5 同源基因对的表达谱分析 5
2 结果与结论 5
2.1 禾谷类植物淀粉合成关键酶基因的鉴定 5
2.2 禾谷类植物淀粉合成关键酶基因的分类情况 6
2.3 禾谷类植物淀粉合成关键酶蛋白的序列特征 7
2.4 禾谷类植物淀粉合成关键酶基因同源对的适应性进化 9
2.5禾谷类植物淀粉合成关键酶基因同源对的表达特征 11
3 讨论与结论 12
参考文献 13
致谢 15
禾谷类植物淀粉合成关键酶的鉴定与比较分析
引言
淀粉是植物个体生长发育过程所需要的营养物质,也是决定禾谷类作物籽粒产量和品质的关键因子[1]。在植物体内，淀粉分为两类：一类是贮藏淀粉，主要存在于植物的块根、块茎和种子的胚乳中；另一类是瞬时淀粉，在植物叶片的叶绿体中合成[2]。淀粉不仅是人们食物的主要组成成分，而且还是一种被广泛应用于医药、造纸、粘合剂、纺织、酿酒及生物降解塑料等行业的重要工业原料[3]。
淀粉是一类不易溶解的由葡萄糖分子聚缩而成的多聚糖,根据其分子结构的差异分为直链淀粉和支链淀粉两类[4]。直链淀粉是以α-1,4-糖苷键将葡萄糖残疾连接而成的无分支的螺旋结构；支链淀粉是葡萄糖残基以α-1,4-糖苷键相连而成的葡萄糖链，在支链处以α-1,6-糖苷键连接[5]。当直链淀粉遇到碘时，会形成淀粉-碘螺旋型复合物，呈蓝紫色，该复合物在 620~680nm 处有最大光吸收值；当支链淀粉遇碘时，呈现紫红色，在 530~550nm 处有最大光吸收值[6]。
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