甘薯抗茎线虫病基因的AFLP标记的开发

以甘薯抗茎线虫病品种徐781和感茎线虫病品种徐薯18的杂交F1分离群体的186株单株为材料，利用分离群体分组分析法（BSA法）和AFLP技术，在抗感池中共筛选了800对AFLP引物，结果表明其中245对引物具有多态性。用这245对引物检测两亲本以及建池单株，发现引物组合E2M23和E33M20分别在抗病单株中扩增出1条在感病单株中未出现的特异条带，长度分别约为500 bp和200 bp，认为这2个AFLP标记与甘薯抗茎线虫病基因连锁，分别命名为E2M23500和E33M20200。根据这2个AFLP标记对F1代186个单株的扩增结果，经Mapmaker 3.0软件分析，发现这2个分子标记与抗茎线虫病基因位于同一连锁群并紧密连锁，它们与抗茎线虫病基因间的遗传距离分别为6.94 cM和11.1 cM。用这2个分子标记对10个中国甘薯主栽品种进行检测，所得结果与常规方法鉴定结果完全一致，表明2个分子标记可用于甘薯抗茎线虫病分子标记辅助育种。

Development of AFLP Markers Linked to Stem Nematode Resistance Gene in Sweetpotato (Ipomoea batatas (L.) Lam.)

AFLP markers linked to stem nematode resistance gene were developed in sweetpotato (Ipomoea batatas (L.) Lam.). Using bulked segregant analysis (BSA), 800 AFLP primer combinations were screened in the resistant and susceptible DNA bulks from the 186 progenies of F1 single-cross population of Xu781 (resistant parent) × Xushu 18 (susceptible parent), and 245 of them showed polymorphic bands between the two bulks. Primer combinations detecting polymorphism between the two bulks were used to screen the parents and eight individuals from each of the bulks. The results showed that E2M23 and E33M20 produced a specific band of about 500 bp and 200 bp in length, respectively, in the resistant plants but not in the susceptible plants, suggesting the markers named E2M23500 and E33M20200 linked to a gene for stem nematode resistance. The amplified analysis of the 186 F1 individuals indicated that the genetic distance was 6.9 cM and 11.1 cM, respectively, between the two markers and the stem nematode resistance gene with Mapmaker 3.0. These two AFLP markers were used to identify 10 sweetpotato varieties widely planted in China and the results were consistant with those of conventional resistance identification, indicating that the two markers can be used in molecular marker-assisted breeding for stem nematode resistance of sweetpotato.