The diversification of Citrus clementina hort. ex tan., a vegetatively propagated crop species
The diversification of Citrus clementina hort. ex tan., a vegetatively propagated crop species
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DOI：
10.1006/mpev.2001.1008
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发表时间：
2001-11-01
影响因子：
4.1
通讯作者：
Asíns, MJ
中科院分区：
文献类型：
--
作者：
Bretó, MP;Ruiz, C;Asíns, MJ
克莱门氏小柑橘因其高品质而成为最重要的栽培柑橘类柑橘之一。与甜橙和蜜柑的情况一样，通过分子标记分析，该物种内的遗传变异性很小，因为现有品种不是通过杂交获得的，而是通过影响农艺性状的自发突变选择获得的。这至少可以部分地解释，与分子标记的变异性相比，农艺性状具有更大的多样性。另一个可能的（非排他性的）原因是所使用的分子标记类型并未集中于主要涉及克莱门氏小柑橘新品种起源的分子变化类型；即，所有变异来源是否都同等地参与这些植物的多样化？为了回答这个问题，分别使用基于随机序列引物、简单序列重复引物和可能揭示点突变的逆转录转座子序列以及体细胞重组和转座子活性的不同标记来比较24个克莱门氏小柑橘品种之间的变异水平。他们的 ISSR、RAPD 和 AFLP 分析仅提供了两个多态性条带，仅区分了两个品种。 SSR 没有发现变异，即没有检测到通过体细胞重组产生的新等位基因。相反，逆转录转座子附近序列的扩增产生了更多的多态性（前面提到的标记类型为 14.6% vs 2.4%）。两个地理上相距较远的群体，一个来自北非，另一个来自西班牙，其进化与基于 IRA-P 标记的多态性一致，该标记至少锚定在两个不同的 Copia 样逆转录转座子序列上。因此，这项研究表明，这种类型的移动元件的 DNA 比该克隆谱系中其他标记的 DNA 进化得更快。 (C) 2001 年学术出版社。
Clementines, due to their high quality, are one of the most important cultivated citrus mandarins. As in the case of sweet orange and satsuma mandarins, genetic variability within this species is minimal when analyzed by molecular markers, because the existing varieties have not been obtained through hybridization, but through the selection of spontaneous mutations affecting traits of agronomic interest. This would explain, at least in part, the greater diversity for agronomic traits when compared to the variability for molecular markers. Another possible (nonexclusive) reason is that the types of molecular marker used are not focused on the kind of molecular change mainly involved in the origination of new clementine cultivars; i.e., are all sources of variation equally involved in the diversification of these plants? To answer this question, different kinds of markers based on primers of random sequence, simple sequence repeats, and retrotransposon sequences that may reveal point mutations, and somatic recombination and transposon activity, respectively, were used to compare the level of variability among 24 clementine varieties. Their ISSR, RAPD, and AFLP analysis provided only two polymorphic, bands, distinguishing just two varieties. No variability was found by SSRs, i.e., no new allele arising through somatic recombination was detected. Instead, the amplification of sequences adjacent to retrotransposons yielded a higher number of polymorphisms (14.6 vs 2.4% for the previous mentioned marker types). Two geographical distant groups, one from North Africa and the other from Spain, have evolved in agreement with polymorphisms based on IRA-P markers anchored to, at least, two different Copia-like retrotransposon sequences. Therefore, this study suggests that the DNA of this type of mobile elements is evolving faster than the DNA of other markers in this clonal lineage. (C) 2001 Academic Press.