The effect of cassava mosaic disease on the genetic diversity of cassava in Uganda
The effect of cassava mosaic disease on the genetic diversity of cassava in Uganda
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DOI：
10.1007/s10681-005-2959-3
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发表时间：
2005-11-01
期刊：
影响因子：
1.9
通讯作者：
Westerbergh, A
中科院分区：
文献类型：
--
作者：
Kizito, EB;Bua, A;Westerbergh, A
木薯（Manihot esculenta）是一种热带作物，生长在非洲，拉丁美洲和东南亚。木薯是在两次独立的活动中从拉丁美洲引入西非和东非的。在乌干达，木薯花叶病（CMD）是对木薯生存的一个严重威胁。自19世纪50年代引入木薯以来，乌干达发生了两次值得注意的CMD流行，造成了严重的损失。利用SSR分子标记研究了乌干达5个玉米花叶病高发区和低发区的玉米花叶病对遗传多样性的影响。令人惊讶的是，检测到高基因多样性。大部分的多样性存在于种群内，而农业生态区和高，低发病率地区之间的多样性很小。高度的遗传多样性表明了一种机制，通过这种机制，乌干达农民积极参与不断测试和采用新的基因型来维持多样性，以满足他们的不同需求。然而，尽管有很高的遗传多样性，我们发现在CMD发病率高的地区丢失了罕见的等位基因。为了研究渐渗历史对基因库的影响，还研究了东非和西非之间的遗传分化。东非的乌干达和坦桑尼亚以及西非的加纳的品种之间存在遗传相似性。因此，没有证据表明木薯基因库分化为西部和东部遗传谱系。然而，引进到东非和西非的木薯的遗传组成可能存在的差异可能已经被种质移动所减少。
Cassava (Manihot esculenta) is a tropical crop that is grown in Africa, Latin America and Southeast Asia. Cassava was introduced from Latin America into West and East Africa at two independent events. In Uganda a serious threat to cassava's survival is the cassava mosaic disease (CMD). Uganda has had two notable CMD epidemics since the introduction of cassava in the 1850s causing severe losses. SSR markers were used to study the effect of CMD on the genetic diversity in five agroecologies in Uganda with high and low incidence of CMD. Surprisingly, high gene diversity was detected. Most of the diversity was found within populations, while the diversity was very small among agroecological zones and the high and low CMD incidence areas. The high genetic diversity suggests a mechanism by which diversity is maintained by the active involvement of the Ugandan farmer in continuously testing and adopting new genotypes that will serve their diverse needs. However, in spite of the high genetic diversity we found a loss of rare alleles in areas with high CMD incidence. To study the effect of the introgression history on the gene pool the genetic differentiation between East and West Africa was also studied. Genetic similarities were found between the varieties in Uganda and Tanzania in East Africa and Ghana in West Africa. Thus, there is no evidence for a differentiation of the cassava gene pool into a western and an eastern genetic lineage. However, a possible difference in the genetic constitution of the introduced cassava into East and West Africa may have been diminished by germplasm movement.