Genetic and physical localization of the root-knot nematode resistance locus Mi in tomato
Genetic and physical localization of the root-knot nematode resistance locus Mi in tomato
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DOI：
10.1007/s004380050660
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发表时间：
1998-02-01
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影响因子：
--
通讯作者：
Williamson, VM
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文献类型：
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作者：
Kaloshian, I;Yaghoobi, J;Williamson, VM
作为旨在分离根结线虫抗性基因 Mi 的基于图谱的克隆策略的一部分，对番茄 F2 群体进行了分析，以确定靠近该经济重要基因的重组点。使用形态学标记筛选了总共 21089 株 F2 后代植物。使用基于 PCR 的侧翼标记筛选了另外 1887 个 F2。使用新开发的 AFLP 标记和源自物理作图的粘粒亚克隆的 RFLP 标记对重组体进行精细结构作图，将 Mi 定位到约 550 kb 的基因组区域。重组体的低频率表明重组在这些杂交中普遍受到抑制并且交叉仅限于特定区域。为了解决这个问题，秘鲁番茄（Lycopersicon peruvianum）种群（Mi 最初是从该物种渗入的）被开发出来，该种群因抗性而被隔离。使用 PCR、RFLP 和 AFLP 标记对该群体进行筛选，鉴定出几种在 Mi 附近具有交叉的植物。秘鲁乳杆菌杂交的 Mi 区域的重组频率大约高出八倍。然而，即使在野生物种杂交中，重组位点在该地区的分布也不均匀。通过结合来自 L. esculentum 和 L. peruvianum 重组分析的数据，可以将 Mi 定位到基因组中小于 65 kb 的区域。
As part of a map-based cloning strategy designed to isolate the root-knot nematode resistance gene Mi, tomato F2 populations were analyzed in order to identify recombination points close to this economically important gene. A total of 21089 F2 progeny plants were screened using morphological markers. An additional 1887 F2 were screened using PCR-based flanking markers. Fine-structure mapping of recombinants with newly developed AFLP markers, and RFLP markers derived from physically mapped cosmid subclones, localized Mi to a genomic region of about 550 kb. The low frequency of recombinants indicated that recombination was generally suppressed in these crosses and that crossovers were restricted to particular regions. To circumvent this problem, a population of Lycopersicon peruvianum, the species from which Mi was originally introgressed, that was segregating for resistance was developed. Screening of this population with PCR, RFLP and AFLP markers identified several plants with crossovers near Mi. Recombination frequency was approximately eight-fold higher in the Mi region of the L. peruvianum cross. However, even within the wild species cross, recombination sites were not uniformly distributed in the region. By combining data from the L. esculentum and L. peruvianum recombinant analyses, it was possible to localize Mi to a region of the genome spanning less than 65 kb.