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高山松(Pinus densata)是油松(P.tabulaeformis)与云南松(P.yunnanensis)自然杂交产生的同倍性杂种,分布于青藏高原东南缘,占据了油松和云南松两个亲本种都不能正常生长的高海拔地带。为了揭示高山松、油松和云南松脱氢抗坏血酸还原酶(DHAR)基因的组成和功能分化,分别从高山松、油松和云南松中克隆到2类DHAR基因(DHAR1与DHAR2)。组织表达模式分析表明,这6个基因在根、韧皮部、叶和芽中均有表达;通过系统发育分析发现,高山松在物种形成过程中保留了油松的DHAR1拷贝以及云南松的DHAR2拷贝;酶学性质分析则表明,高山松与油松DHAR1蛋白对底物具有相似的催化活性、催化效率、最适pH和热力学稳定性,但其催化活性比云南松DHAR1蛋白高约300倍。高山松DHAR2蛋白对底物的催化活性和热力学稳定性均高于油松DHAR2蛋白。高山松DHAR基因在生化功能上显示出优于或类似亲本DHAR,这种优势功能的选择与杂种独特的生态适应性可能有重要的相关性。
Pinus densata is the same-ploid hybrid of natural hybridization of P. tabulaeformis and P. yunnanensis, distributed in the southeastern margin of the Qinghai-Tibet Plateau, occupying both of the two parental species of Pinus tabulaeformis and Pinus yunnanensis Can not grow normally in high-altitude areas. To reveal the composition and functional differentiation of dehydroascorbate reductase (DHAR) genes in Pinus taiwanensis, Pinus tabulaeformis and Pinus yunnanensis, two DHAR genes (DHAR1 and DHAR2) were cloned from Pinus tabulaeformis, Pinus tabulaeformis and Pinus yunnanensis. Tissue expression pattern analysis showed that these six genes were expressed in roots, phloem, leaves and buds. Phylogenetic analysis showed that P. elegans retained copies of DHAR1 and DHAR2 copies of Pinus tabulaeformis during species formation. Properties analysis showed that the DHAR1 protein of Pinus tabulaeformis and Pinus tabulaeformis had similar catalytic activity, catalytic efficiency, optimum pH and thermodynamic stability, but its catalytic activity was about 300 times higher than DHAR1 protein of Pinus yunnanensis. Alpine pine DHAR2 protein on the substrate catalytic activity and thermodynamic stability were higher than the P. tabulaeformis DHAR2 protein. Alpine pine DHAR gene shows superior or similar parent DHAR in biochemical function, and the selection of this dominant function may have important correlation with the unique ecological adaptability of hybrids.