Bressan E A, Briner Neto T, Zucchi M I, Rabello R J, Veasey E A
Departamento de Genética, Escola Superior de Agricultura "Luiz de Queiroz", Universidade de São Paulo, Piracicaba, SP, Brasil.
Agência Paulista de Tecnologia dos Agronegócios, Pólo Apta Centro Sul, Piracicaba, SP, Brasil.
Genet Mol Res. 2014 Jan 21;13(1):425-37. doi: 10.4238/2014.January.21.10.
Of the 600 known yam species, only 10 are utilized as food, and the Dioscorea cayenensis/D. rotundata species complex is among the most cultivated. In Brazil, these species are commercially cultivated in the northeast region and are cultivated in the south and southeast regions as subsistence crops by traditional agriculturists. This study aimed to evaluate the genetic diversity of 21 local varieties of D. cayenensis and 2 D. rotundata accessions using 7 isozymic loci and 24 morphological markers, and to investigate the diversity distribution in different levels of organization, such as swidden fields and communities of Vale do Ribeira. Cluster analyses for both the isozymic and morphological data separated the 2 D. rotundata accessions from the D. cayenensis accessions from Vale do Ribeira. The analysis with morphological characteristics showed the presence of 2 subgroups (Iguape and Cananéia) within group I, which included all of the local varieties from Vale do Ribeira; this result may indicate the influence of the cultural units on the morphological variation. Molecular analysis of variance indicated that most of the isozymic variability was concentrated among swiddens within communities (42.5%) and within communities (40.3%). Most of the morphological variability was also concentrated among swidden fields within communities (44.8%). The correlation between geographic and genetic distances indicated that neither morphological (r = 0.17) nor isozymic diversity (r = -0.15) is structured in space. Thus, the traditional agriculturists of Vale do Ribeira maintain and manage a great diversity of D. cayenensis varieties in their communities.
在已知的600种山药品种中，只有10种被用作食物，而甘薯/圆山药复合种是种植最为广泛的品种之一。在巴西，这些品种在东北地区进行商业化种植，在南部和东南部地区则由传统农民作为自给作物种植。本研究旨在利用7个同工酶位点和24个形态学标记评估21个甘薯地方品种和2个圆山药种质的遗传多样性，并调查不同组织水平（如刀耕火种农田和里贝拉河谷社区）的多样性分布。对同工酶和形态学数据进行的聚类分析将2个圆山药种质与来自里贝拉河谷的甘薯种质区分开来。形态特征分析显示，第一组内存在2个亚组（伊瓜佩和卡纳内亚），该组包括来自里贝拉河谷的所有地方品种；这一结果可能表明文化单元对形态变异的影响。分子方差分析表明，大部分同工酶变异集中在社区内的刀耕火种农田之间（42.5%）和社区内（40.3%）。大部分形态变异也集中在社区内的刀耕火种农田之间（44.8%）。地理距离与遗传距离之间的相关性表明，形态多样性（r = 0.17）和同工酶多样性（r = -0.15）在空间上均无结构。因此，里贝拉河谷的传统农民在其社区中维持和管理着甘薯品种的巨大多样性。
