Low validation rate of quantitative trait loci for Gibberella ear rot resistance in European maize
Low validation rate of quantitative trait loci for Gibberella ear rot resistance in European maize
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DOI：
10.1007/s00122-016-2802-3
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发表时间：
2017-01-01
影响因子：
5.4
通讯作者：
Miedaner, Thomas
中科院分区：
文献类型：
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作者：
Brauner, Pedro Correa;Melchinger, Albrecht E.;Miedaner, Thomas
在两种不同的遗传背景下测试了玉米赤霉穗腐病抗性的六个数量性状位点（QTL）；三个QTL在少数近等基因系对中表现出作用。赤霉耳腐病(GER)的数量性状位点(QTL)作图研究很少，但迄今为止尚未验证QTL。在将 QTL 验证应用于标记辅助选择 (MAS) 程序之前，需要谨慎行事。我们的目标是 (1) 验证 6 个 QTL 的 GER 抗性，(2) 评估两个遗传背景的 QTL，(3) 研究目标基因渗入之外的遗传背景。通过循环回交形成分离单个 QTL（Qger1、Qger2、Qger10、Qger13、Qger16 或 Qger21）的成对近等基因系 (NIL)，直至 BC3S2 代。携带QTL的供体亲本(DP)与易感(UH009)和中度抗性(UH007)轮回亲本回交。 MAS 使用覆盖每个 QTL 周围 40 cM 区域的 5 个 SNP 标记进行。所有 NIL 均采用 MaizeSNP50 测定进行基因分型，并针对 GER 严重程度以及脱氧雪腐镰刀菌烯醇和玉米赤霉烯酮含量进行表型分析。性状显着相关（P < 0.001）。在具有 UH009 遗传背景的 34 个 NIL 对中，有 3 对在三个 QTL（Qger1、Qger2、Qger13）的至少一个性状上显示出显着差异。在具有 UH007 遗传背景的 25 个 NIL 对中，有 5 对在两个 QTL（Qger2、Qger21）的至少一个性状上显示出显着差异。然而，Qger16、Qger10 和 Qger13 最有可能是误报。由于连锁阻力和/或非目标区域中 DP 的残留基因座的上位性，遗传背景可能会影响 NIL 对的比较。总之，验证率低得令人失望，这进一步表明GER抗性是由许多低效QTL控制的。
Six quantitative trait loci (QTL) for Gibberella ear rot resistance in maize were tested in two different genetic backgrounds; three QTL displayed an effect in few near isogenic line pairs.Few quantitative trait loci (QTL) mapping studies for Gibberella ear rot (GER) have been conducted, but no QTL have been verified so far. QTL validation is prudent before their implementation into marker-assisted selection (MAS) programs. Our objectives were to (1) validate six QTL for GER resistance, (2) evaluate the QTL across two genetic backgrounds, (3) investigate the genetic background outside the targeted introgressions. Pairs of near isogenic lines (NILs) segregating for a single QTL (Qger1, Qger2, Qger10, Qger13, Qger16, or Qger21) were developed by recurrent backcross until generation BC3S2. Donor parents (DP) carrying QTL were backcrossed to a susceptible (UH009) and a moderately resistant (UH007) recurrent parent. MAS was performed using five SNP markers covering a region of 40 cM around each QTL. All NILs were genotyped with the MaizeSNP50 assay and phenotyped for GER severity and deoxynivalenol and zearalenone content. Traits were significantly (P < 0.001) intercorrelated. Out of 34 NIL pairs with the UH009 genetic background, three pairs showed significant differences in at least one trait for three QTL (Qger1, Qger2, Qger13). Out of 25 NIL pairs with the UH007 genetic background, five pairs showed significant differences in at least one trait for two QTL (Qger2, Qger21). However, Qger16, Qger10 and Qger13 were most likely false positives. The genetic background possibly affected NIL pairs comparisons due to linkage drag and/or epistasis with residual loci from the DP in non-target regions. In conclusion, validation rates were disappointingly low, which further indicates that GER resistance is controlled by many low-effect QTL.