Manihot esculenta Crantz is originally from the Amazon region of Brazil, which has the highest genetic diversity. Due to the wide adaptation of cassava to the most diverse environments, the evolutionary forces acted on the crop, resulting in a more complex genetic structure. This study evaluated the population structure and the genetic diversity through 25 SSR markers of 144 sweet cassava accessions collected in seven places in the south of Brazil. All the loci analyzed were polymorphic and showed several alleles per loci with a mean of 3.36 alleles and 38 rare alleles in the population. The mean value of polymorphism information content (PIC) was 0.488, which indicates that the markers were informative and the mean observed heterozygosity was 0.644, while the mean expected heterozygosity was 0.557. The sweet cassava accessions were divided into 10 groups based on the population structure analysis. There was a moderate genetic differentiation (PhiPT = 0.106) among the sweet cassava subpopulations. The wide genetic variability among the studied accessions of sweet cassava demonstrates the importance of the emergency in the conservation of plants in germplasm banks, because the intense change in agriculture; the expansion of areas occupied by soybeans, corn, and other crops; and also the farmers’ migration from rural areas to urban areas reduced cassava cultivation over time, and as a consequence, genetic variability has been lost.

中文翻译：

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巴西巴拉那州和圣卡塔琳娜州甜木薯种质的种群结构和遗传多样性

Manihot esculenta Crantz 原产于巴西的亚马逊地区，该地区具有最高的遗传多样性。由于木薯对最多样化环境的广泛适应性，进化力量作用于作物，导致更复杂的遗传结构。本研究通过在巴西南部 7 个地方收集的 144 个甜木薯种质的 25 个 SSR 标记评估种群结构和遗传多样性。分析的所有基因座都是多态的，每个基因座显示几个等位基因，群体中平均有 3.36 个等位基因和 38 个稀有等位基因。多态性信息含量（PIC）的平均值为0.488，表明标记具有信息性，平均观察杂合度为0.644，而平均预期杂合度为0.557。基于群体结构分析将甜木薯种质分为10组。甜木薯亚群之间存在适度的遗传分化（PhiPT = 0.106）。所研究的甜木薯种质之间的广泛遗传变异证明了紧急情况在种质库中保护植物的重要性，因为农业的剧烈变化；扩大大豆、玉米等作物的种植面积；而且随着时间的推移，农民从农村地区迁移到城市地区减少了木薯种植，因此，遗传变异性已经丧失。所研究的甜木薯种质之间的广泛遗传变异证明了紧急情况在种质库中保护植物的重要性，因为农业的剧烈变化；扩大大豆、玉米等作物的种植面积；而且随着时间的推移，农民从农村地区迁移到城市地区减少了木薯种植，因此，遗传变异性已经丧失。所研究的甜木薯种质之间的广泛遗传变异证明了紧急情况在种质库中保护植物的重要性，因为农业的剧烈变化；扩大大豆、玉米等作物的种植面积；而且随着时间的推移，农民从农村地区迁移到城市地区减少了木薯种植，因此，遗传变异性已经丧失。