3种检测番茄抗根结线虫Mi基因分子标记法的比较

[目的] Mi基因是目前番茄遗传育种及生产实践中应用最为广泛的根结线虫抗源，通过对3种分子标记法检测番茄中Mi基因的结果进行比较与分析，以期为番茄抗根结线虫遗传育种提供准确、高效的分子鉴定方法。[方法]采用酶切扩增多态性序列（CAPS）、引物对组合以及序列特征扩增区（SCAR）3种分子标记法分别检测16个番茄品种的Mi基因及其基因型，同时采用人工接种法测定番茄品种对南方根结线虫的抗、感性。[结果]针对上述品种，3种分子标记法的检测结果存在着明显的差异，CAPS法检测全部供试番茄均含Mi基因，除‘线虫绝39号’外均为Mi/Mi纯合基因型；而PM3Fb/PM3Rb、PMiF3/PMiR3引物对组合检测和SCAR标记Mi23F/Mi23R检测的结果均显示有9个品种含Mi基因，前者检测表明‘VFN’‘双抗265’和‘双抗228’为Mi/Mi纯合基因型，但后者检测则显示仅‘VFN’和‘线虫绝39号’为Mi/Mi纯合基因型。接种测定结果显示：‘VFN’和‘线虫绝3号’为南方根结线虫免疫品种，‘双抗228’‘仙客1号’‘Sparta’和‘线虫绝39号’为高抗品种，‘双抗265’和‘牟番1号’为抗病品种，其余均为感病品种。[结论]CAPS法容易产生假阳性，不适用于番茄Mi基因的检测，而PM3Fb/PM3Rb、PMiF3/PMiR3的引物对组合和SCAR标记Mi23F/Mi23R这2种方法能够相对准确地检测番茄Mi基因，其中SCAR标记经单次PCR反应即可直接鉴定Mi基因的有无及其基因型，应用更为便捷。
[Objectives]The Mi gene is the most widely used genetic resource for resistance to root-knot nematodes in tomato breeding and production practice. In order to provide the molecular techniques for accurate and efficient identificaiton of Mi gene in tomato breeding,three different molecular markers were compared and analysed for the detection of Mi gene in tomato cultivars.[Methods]The Mi gene and its genotype in 16 tomato cultivars were detected using the cleaved amplified polymorphic sequences(CAPS),primer pairs combination and sequence characterized amplified regions(SCAR),respectively. Meanwhile,the resistance of these cultivars to Meloidogyne incognita was evaluated by the artificial inoculation test.[Results]Using three different molecular markers revealed the detection of Mi gene in 16 tomato cultivars showing the appearently differences. The detection by CAPS showed that all cultivars contained Mi gene,and all cultivars,except ‘Xianchongjue 39’,were homozygous genotype of Mi/Mi. The detection by the combination of markers PM3Fb/PM3Rb and PMiF3/PMiR3 and by the SCAR marker of Mi23F/Mi23R both showed that 9 cultivars contained Mi gene. The former one detected ‘VFN’ ‘Shuangkang 265’ and ‘Shuangkang 228’ having homozygous genotype of Mi/Mi,however,the latter one detected ‘VFN’ and ‘Xianchongjue 39’ having homozygous genotype of Mi/Mi. Inoculation test revealed that the cultivars ‘VFN’ and ‘Xianchongjue 3’ were immune to M.incognita, ‘Shuangkang 228’ ‘Xianke 1’ ‘Sparta’ and ‘Xianchongjue 39’ were highly resistant, ‘Shuangkang 265’ and ‘Moufan 1’ were resistant,and the rest cultivars were susceptible.[Conclusions]The detection of CAPS easily producted the false-positive results,which is not suitable for applying in the identification of Mi gene in tomato. The combination of markers PM3Fb/PM3Rb and PMiF3/PMiR3 and the SCAR marker of Mi23F/Mi23R both could be used for detecting the Mi gene in tomato with