Birmeta Genet, Nybom Hilde, Bekele Endashaw
Department of Crop Science, Swedish University of Agricultural Sciences, Alnarp, Sweden.
Hereditas. 2004;140(2):139-48. doi: 10.1111/j.1601-5223.2004.01792.x.
In southwest Ethiopia, the cultivation area of Ensete ventricosum (enset) overlaps with the natural distribution area of this species. Analyses of genetic diversity were undertaken using RAPD to provide information for conservation strategies as well as evidence of possible gene flow between the different gene pools, which can be of interest for future improvement of cultivated enset. The extent of RAPD variation in wild enset was investigated in 5 populations in the Bonga area (Kefficho administrative region) and 9 cultivated clones. Comparisons were also made with some Musa samples of potential relevance for crop improvement. Nine oligonucleotide primers amplified 72 polymorphic loci. Population differentiation was estimated with the Shannon index (G'(ST)=0.10), Nei's G(ST) (0.12) and AMOVA (Phi(ST)=0.12), and appears to be relatively low when compared with outbreeding, perennial species in general. Cluster analysis (UPGMA) and principal component analysis (PCA) similarly indicated low population differentiation, and also demonstrated that cultivated clones essentially clustered distinctly from wild enset samples, suggesting that the present-day cultivated enset clones have been introduced to domestication from a limited number of wild progenitors. In addition, subsequent gene flow between wild and cultivated enset may have been prohibited by differences between modes of propagation and harvesting time; cultivated enset is propagated vegetatively through sucker production and the plant is generally harvested before maturity or flower set, thereby hindering pollination by wild enset or vice versa. A significant correlation was not found between genetic and geographical distances. The relatively high total RAPD diversity suggests that wild enset populations in the Bonga area harbour genetic variability which could potentially act as a source for useful or rare genes in the improvement of cultivated enset. As expected, E. ventricosum was clearly differentiated from the analysed Musa samples, that clustered in accordance with the present morphology- and molecular marker-based taxonomy of the genus.
在埃塞俄比亚西南部，埃塞俄比亚香蕉（Ensete ventricosum）的种植区域与该物种的自然分布区域重叠。利用随机扩增多态性DNA（RAPD）进行遗传多样性分析，以便为保护策略提供信息，并为不同基因库之间可能的基因流动提供证据，这对于未来埃塞俄比亚香蕉栽培品种的改良可能具有重要意义。在邦加地区（凯菲乔行政区）的5个野生埃塞俄比亚香蕉种群和9个栽培无性系中，研究了野生埃塞俄比亚香蕉RAPD变异的程度。还与一些对作物改良可能具有潜在相关性的芭蕉属样本进行了比较。9个寡核苷酸引物扩增出72个多态性位点。用香农指数（G'(ST)=0.10）、内氏G(ST)（0.12）和分子方差分析（Phi(ST)=0.12）估计种群分化，与一般的异交多年生物种相比，其分化程度似乎相对较低。聚类分析（非加权组平均法）和主成分分析同样表明种群分化程度较低，并且还表明栽培无性系基本上与野生埃塞俄比亚香蕉样本明显聚类，这表明当今栽培的埃塞俄比亚香蕉无性系是从有限数量的野生祖先驯化而来的。此外，野生和栽培埃塞俄比亚香蕉之间随后的基因流动可能因繁殖方式和收获时间的差异而受到阻碍；栽培埃塞俄比亚香蕉通过吸芽进行无性繁殖，植株通常在成熟或开花前收获，从而阻碍了野生埃塞俄比亚香蕉的授粉，反之亦然。未发现遗传距离与地理距离之间存在显著相关性。相对较高的总RAPD多样性表明，邦加地区的野生埃塞俄比亚香蕉种群具有遗传变异性，这有可能作为改良栽培埃塞俄比亚香蕉中有用或稀有基因的来源。正如预期的那样，埃塞俄比亚香蕉与所分析的芭蕉属样本明显区分开来，这些样本根据该属目前基于形态学和分子标记的分类法进行聚类。
