基于Glb 1基因序列的西南地区玉米地方品种的系统进化

Phylogeny of Maize Landraces in Southwestern China Based on Glb 1 Sequences

为探讨我国西南地区玉米地方品种Glb 1基因序列多态性,对40份西南地区玉米地方品种的Glb 1基因序列测序,并与Gen Bank中来自普通玉米、小颖玉米、繁茂玉米和摩擦禾的19条同源序列比对。结果表明,来自西南地区四川、重庆、云南和贵州的玉米地方品种分别有35、25、33和25个多态性位点,其遗传多态性分别是小颖玉米的87%、86%、85%和71%,8个种群遗传多态性指数的大小排序为小颖玉米、四川地方品种、重庆地方品种、云南地方品种、贵州地方品种、普通玉米、磨擦禾和繁茂玉米,Tajima’D、Fu&Li’D和Fu&Li,F检验表明Glb 1基因是中性进化基因。比较种群间DNA序列的共有多态性和固定差异,玉米地方品种与小颖玉米、繁茂玉米、磨擦禾间存在较高的固定差异和较低的共有多态性。Glb 1基因的系统进化关系及网状关系分析为玉蜀黍属的分类系统提供了佐证,四川玉米地方品种有较高的遗传多态性支持我国玉米由印度经西藏传入四川的论点。

To explore the DNA polymorphism of Glb 1 genes in maize landraces from Southwest China, we cloned and sequenced the DNA sequences from 40 maize landraces, and downloaded the homologous sequences of 19 individuals representing common maize, parviglumis, Z. luxurians, and T. dactyloides from Gen Bank. By aligning these sequences and analyzing DNA variations in Glb 1 loci, we found 35, 25, 33, and 25 polymorphism sites in maize landraces from Sichuan, Chongqing, Yunnan, and Guizhou, respectively. Their genetic polymorphisms were 87%, 86%, 85%, and 71% of that in parviglumis. On the basis of estimates of π per base pair and θ per base pair, the highest level of sequence variation was found in parviglumis, followed in turn by maize landraces from Sichuan, landraces from Chongqing, landraces from Yunnan, landraces from Guizhou, common maize, T. dactyloides, and Z. luxurians. The estimates of Tajima＇s and Fu Li＇s D statistic for Glb 1 gene were negative in the eight taxa, suggesting that neutrality cannot be rejected. In comparison, more fixed differences than shared polymorphisms between maize landraces and parviglumis, Z. luxurians, as well as T. dactyloides were found. The genealogical and network analysis provided the evidence for the genus Zea taxonomy. Additionally, genetic diversity of landraces was greater in Sichuan than in the other three regions. This result supports the hypothesis that the first maize migration was from India to Sichuan by way of Tibet in China.