Vieira P M H, Arêdes F A S, Ferreira A, Ferreira M F S
Laboratório de Melhoramento Genético Vegetal, Departamento de Biologia, Centro de Ciências Agrárias, Universidade Federal do Espírito Santo, Alegre, ES, Brasil.
Universidade Estadual Norte Fluminense, Campos dos Goytacazes, RJ, Brasil.
Genet Mol Res. 2016 Sep 2;15(3):gmr8562. doi: 10.4238/gmr.15038562.
Nematodes are important pests of soybean throughout the world and cause high yield losses. As a control strategy, the identification of resistance genes is an important aim of breeding studies. Plants possess resistance genes (R), which are responsible for the recognition of pathogens and activation of the defense system. R genes and resistance gene analogs (RGAs) possess conserved domains, from which nucleotide-binding site is the most common. Using degenerate primers originating from these domains, it is possible to identify and isolate sequences of R and RGA genes. In this study, soybean genotypes resistant to the nematodes Heterodera glycines, Meloidogyne incognita, M. javanica, and M. enterolobii were compared by the use of RGAs and simple sequence repeat (SSR) markers. Forty-six soybean genotypes were studied, including plant introductions (PIs), commercial crops, and source of resistance genotypes. Thirteen combinations of RGA primers and different SSRs linked to QTLs were used to confirm resistance to soybean cyst nematodes (SCN). Fragments associated with resistance to the studied nematodes were amplified in the source of resistance and PI genotypes. RGA markers were efficient at distinguishing groups of genotypes that were resistant and susceptible to Meloidogyne spp and SCN. Combinations of specific primers were identified through their ability to amplify nucleotide sequences from possible resistance candidate genes. SSR markers contributed to the analysis of SCN race specificity, showing that the QTLs identified by these markers are distinct from those identified by RGA markers.
线虫是全球大豆的重要害虫，会导致高额产量损失。作为一种防治策略，鉴定抗性基因是育种研究的一个重要目标。植物拥有抗性基因（R），这些基因负责识别病原体并激活防御系统。R基因和抗性基因类似物（RGAs）具有保守结构域，其中核苷酸结合位点最为常见。利用源自这些结构域的简并引物，有可能鉴定和分离R基因及RGA基因的序列。在本研究中，通过使用RGAs和简单序列重复（SSR）标记，对大豆抗大豆胞囊线虫（Heterodera glycines）、南方根结线虫（Meloidogyne incognita）、爪哇根结线虫（M. javanica）和恩氏根结线虫（M. enterolobii）的基因型进行了比较。研究了46个大豆基因型，包括植物引进品种（PIs）、商业作物和抗性基因型来源。使用13种RGA引物组合以及与数量性状基因座（QTLs）连锁的不同SSR，来确认对大豆胞囊线虫（SCN）的抗性。在抗性来源和PI基因型中扩增出了与对所研究线虫的抗性相关片段。RGA标记在区分对根结线虫属和大豆胞囊线虫有抗性和易感性的基因型组方面很有效。通过特定引物组合扩增可能的抗性候选基因核苷酸序列的能力来鉴定这些组合。SSR标记有助于分析大豆胞囊线虫生理小种的特异性，表明这些标记鉴定出的QTLs与RGA标记鉴定出的不同。
