Sánchez-de la Vega Guillermo, Castellanos-Morales Gabriela, Gámez Niza, Hernández-Rosales Helena S, Vázquez-Lobo Alejandra, Aguirre-Planter Erika, Jaramillo-Correa Juan P, Montes-Hernández Salvador, Lira-Saade Rafael, Eguiarte Luis E
Departamento de Ecología Evolutiva, Instituto de Ecología, Universidad Nacional Autónoma de México, Mexico, Mexico.
Unidad de Biotecnología y Prototipos, Facultad de Estudios Superiores Iztacala, Universidad Nacional Autónoma de México, Mexico, Mexico.
Front Plant Sci. 2018 Mar 29;9:400. doi: 10.3389/fpls.2018.00400. eCollection 2018.
Analyses of genetic variation allow understanding the origin, diversification and genetic resources of cultivated plants. Domesticated taxa and their wild relatives are ideal systems for studying genetic processes of plant domestication and their joint is important to evaluate the distribution of their genetic resources. Such is the case of the domesticated subspecies ssp. , known in Mexico as , and its wild relative ssp. . The main aim of this study was to use molecular data (microsatellites) to assess the levels of genetic variation and genetic differentiation within and among populations of domesticated across its distribution in Mexico in comparison to its wild relative, , and to identify environmental suitability in previously proposed centers of domestication. We analyzed nine unlinked nuclear microsatellite loci to assess levels of diversity and distribution of genetic variation within and among populations in 440 individuals from 19 populations of cultivated landraces of and from six wild populations of , in order to conduct a first systematic analysis of their genetic resources. We also used species distribution models (SDMs) for to identify changes in this wild subspecies' distribution from the Holocene (∼6,000 years ago) to the present, and to assess the presence of suitable environmental conditions in previously proposed domestication sites. Genetic variation was similar among subspecies ( = 0.428 in , and = 0.410 in ). Nine populations showed significant levels of inbreeding. Both subspecies are well differentiated, and genetic differentiation () among populations within each subspecies ranged from 0.152 to 0.652. Within we found three genetic groups (Northern Mexico, Yucatan Peninsula, including Michoacan and Veracruz, and Pacific coast plus Durango). We detected low levels of gene flow among populations at a regional scale (<0.01), except for the Yucatan Peninsula, and the northern portion of the Pacific Coast. Our analyses suggested that the Isthmus of Tehuantepec is an effective barrier isolating southern populations. Our SDM results indicate that environmental characteristics in the Balsas-Jalisco region, a potential center of domestication, were suitable for the presence of during the Holocene.
对遗传变异的分析有助于了解栽培植物的起源、多样化及遗传资源。驯化分类群及其野生近缘种是研究植物驯化遗传过程的理想系统，它们的结合对于评估其遗传资源的分布很重要。墨西哥的驯化亚种ssp.（在墨西哥被称为 ）及其野生近缘种ssp. 就是这样的例子。本研究的主要目的是利用分子数据（微卫星）评估驯化种在墨西哥分布范围内各群体内部及之间的遗传变异水平和遗传分化，并与其野生近缘种进行比较，同时确定先前提出的驯化中心的环境适宜性。我们分析了9个不连锁的核微卫星位点，以评估来自19个栽培地方品种群体的440个个体以及6个野生群体的个体中，各群体内部及之间的多样性水平和遗传变异分布，从而对其遗传资源进行首次系统分析。我们还使用了物种分布模型（SDMs）来确定该野生亚种从全新世（约6000年前）到现在的分布变化，并评估先前提出的驯化地点是否存在适宜的环境条件。亚种间的遗传变异相似（栽培种中 = 0.428，野生种中 = 0.410）。9个栽培种群体表现出显著的近亲繁殖水平。两个亚种分化明显，每个亚种内群体间的遗传分化（）范围为0.152至0.652。在栽培种中，我们发现了三个遗传组（墨西哥北部、尤卡坦半岛，包括米却肯州和韦拉克鲁斯州，以及太平洋沿岸加杜兰戈州）。在区域尺度上，除了尤卡坦半岛和太平洋沿岸北部，我们检测到各群体间的基因流水平较低（<0.01）。我们的分析表明，特万特佩克地峡是隔离南部群体的有效屏障。我们的物种分布模型结果表明，巴尔萨斯 - 哈利斯科地区（一个潜在的驯化中心）的环境特征在全新世期间适合栽培种生存。
