Universidade Federal de Uberlândia, Instituto de Genética e Bioquímica, Uberlândia, Brazil.
Universidade Federal de Uberlândia, Instituto de Biologia, Uberlândia, Brazil.
Plant Biol (Stuttg). 2018 Mar;20(2):244-251. doi: 10.1111/plb.12654. Epub 2017 Nov 28.
Since tropical trees often have long generation times and relatively small reproductive populations, breeding systems and genetic variation are important for population viability and have consequences for conservation. Miconia albicans is an obligate, diplosporous, apomictic species widespread in the Brazilian Cerrado, the savanna areas in central Brazil and elsewhere in the Neotropics. The genetic variability would be, theoretically, low within these male-sterile and possibly clonal populations, although some variation would be expected due to recombination during restitutional meiosis. We used ISSR markers to assess genetic diversity of M. albicans and to compare with other tropical trees, including invasive species of Melastomataceae. A total of 120 individuals from six populations were analysed using ten ISSR primers, which produced 153 fully reproducible fragments. The populations of M. albicans presented mean Shannon's information index (I) of 0.244 and expected heterozygosity (H ) of 0.168. Only two pairs of apparently clonal trees were identified, and genetic diversity was relatively high. A hierarchical amova for all ISSR datasets showed that 74% of the variance was found among populations, while only 26% of the variance was found within populations of this species. Multivariate and Bayesian analyses indicated marked separation between the studied populations. The genetic diversity generated by restitutional meiosis, polyploidy and possibly other genome changes may explain the morpho-physiological plasticity and the ability of these plants to differentiate and occupy such a wide territory and different environmental conditions. Producing enormous amounts of bird-dispersed fruits, M. albicans possess weedy potential that may rival other Melastomataceae alien invaders.
由于热带树木的世代时间通常较长，繁殖种群相对较小，因此繁殖系统和遗传变异对种群的生存能力很重要，对保护也有影响。白蔓桃是巴西塞拉多（Cerrado）、巴西中部稀树草原地区和其他新热带地区广泛分布的专性、二倍体、无融合生殖种。尽管在减数分裂过程中会发生重组，因此会产生一些变异，但由于这些雄性不育和可能的无性系种群中的遗传变异性理论上较低。我们使用 ISSR 标记来评估白蔓桃的遗传多样性，并将其与其他热带树木进行比较，包括入侵的野牡丹科物种。使用十个 ISSR 引物对来自六个种群的 120 个个体进行了分析，共产生了 153 个完全可重复的片段。白蔓桃种群的平均香农信息指数（I）为 0.244，预期杂合度（H）为 0.168。仅鉴定出两对明显的无性系树，遗传多样性相对较高。对所有 ISSR 数据集进行层次分析的 AMOVA 表明，74%的变异存在于种群之间，而该物种种群内仅发现 26%的变异。多元分析和贝叶斯分析表明，研究中的种群之间存在明显的分离。减数分裂、多倍体和可能的其他基因组变化产生的遗传多样性可能解释了这些植物的形态生理可塑性以及分化和占据如此广泛的领土和不同环境条件的能力。白蔓桃产生大量的鸟类传播果实，具有杂草的潜力，可能与其他野牡丹科外来入侵物种相媲美。
