西南地区6种魔芋属植物基于cpDNA序列的遗传多样性研究

Genetic diversity of six Amorphophallus species in Southwest China based on cpDNA sequences

关键词:  西南地区, 魔芋属, 遗传多样性, 系统发育, 物种保护

Key words:  Southwest China, Amorphophallus, genetic diversity, phylogeny, species conservation

摘要:

研究野生作物资源的遗传变异及分化机制对种质资源的收集与改良具有重要意义。魔芋是我国西南地区的特色经济作物,但由于受到人为活动干扰,野生种群不断衰退。为评估西南地区魔芋属(Amorphophallus)野生群体的遗传多样性,探究代表性物种的系统发育地位,该研究利用3个叶绿体DNA(cpDNA)片段,分析了魔芋6个物种的遗传多样性,重建了种间系统发育关系。结果表明:(1)西南地区野生魔芋群体的遗传多样性普遍较低,虽然单倍型多样性(H_d)均值为0.428,但近一半群体只有1个单倍型,6个物种整体水平上的单倍型多样性在0.704到0.983之间。(2)在6个物种间检测到高水平的遗传分化,遗传分化系数(F_ST)值在0.481到0.967之间。(3)系统发育分析表明,选取的27个魔芋种主要聚成3个分支:非洲分支、东南亚分支和东亚大陆分支。疣柄魔芋(A. paeoniifolius)隶属于东南亚分支,而东亚大陆分支A包含花魔芋(A. konjac)和西盟魔芋(A. krausei),东亚大陆分支B由东亚魔芋(A. kiusianus)、滇魔芋(A. yunnanensis)和东京魔芋(A. tonkinensis)构成。生境隔离与人为干扰造成了西南地区野生魔芋群体较低的遗传多样性,魔芋属东亚大陆分支的分化可能与早期的快速扩张和生态适应有关。该研究为西南地区魔芋资源的合理保护、可持续利用和杂交育种提供了参考资料。

Abstract:

Investigating mechanisms underlying genetic variation and differentiation of wild resources is critical for the utilization and improvement of crop germplasms. Amorphophallus species is an important economic crop in Southwest China for its glucomannan production. However, the wild populations of this genus are declining due to human activities. To investigate the genetic diversity and phylogenetic relationship of representative Amorphophallus species in Southwest China, the phylogenetic relationships between species were reconducted by using three chloroplast DNA(cpDNA)fragments and analyzing genetic diversity of six Amorphophallus species. The results were as follows:(1)The genetic diversity of wild Amorphophallus populations was generally low with an average haplotype diversity(H_d)of 0.428. In addition, nearly half of the total populations had only one haplotype. The haplotype diversity of each species varied from 0.704 to 0.983.(2)The genetic differentiation between each pair of six species was relatively high, and the genetic differentiation coefficient(F_ST)values ranged from 0.481 to 0.967.(3)The phylogenetic analysis suggested that 27 selected Amorphophallus species should be mainly divided into three clades Africa clade, Southeast Asia clade, and East Asian continent clade. A. paeoniifolius belonged to the Southeast Asia clade. The East Asian continent A clade included A. konjac and A. krausei, and East Asian continent B clade was comprised of A. kiusianus, A. yunnanensis and A. tonkinensis. Geographic isolation and human disturbance could have caused the low genetic diversity in wild populations of Amorphophallus. The divergence of the East Asian continent clade may be driven by the rapid radiation and ecological adaptation in species of this clade. These findings provide theoretical guidance for the conservation, sustainable utilization and breeding of Amorphophallus species in Southwest China.