Clark Anthony J, Sarti-Dvorjak Daniela, Brown-Guedira Gina, Dong Yanhong, Baik Byung-Kee, Van Sanford David A
Department of Plant and Soil Sciences, University of Kentucky Lexington, KY, USA.
Syngenta Seeds Des Moines, IA, USA.
Front Microbiol. 2016 Mar 7;7:277. doi: 10.3389/fmicb.2016.00277. eCollection 2016.
Fusarium head blight (FHB), caused mainly by Fusarium graminearum Schwabe [telomorph: Gibberella zeae Schwein.(Petch)] in the US, is one of the most destructive diseases of wheat (Triticum aestivum L. and T. durum L.). Infected grain is usually contaminated with deoxynivalenol (DON), a serious mycotoxin. The challenge in FHB resistance breeding is combining resistance with superior agronomic and quality characteristics. Exotic QTL are widely used to improve FHB resistance. Success depends on the genetic background into which the QTL are introgressed, whether through backcrossing or forward crossing; QTL expression is impossible to predict. In this study four high-yielding soft red winter wheat breeding lines with little or no scab resistance were each crossed to a donor parent (VA01W-476) with resistance alleles at two QTL: Fhb1 (chromosome 3BS) and QFhs.nau-2DL (chromosome 2DL) to generate backcross and F2 progeny. F2 individuals were genotyped and assigned to 4 groups according to presence/ absence of resistance alleles at one or both QTL. The effectiveness of these QTL in reducing FHB rating, incidence, index, severity, Fusarium-damaged kernels (FDK) and DON, in F2-derived lines was assessed over 2 years. Fhb1 showed an average reduction in DON of 17.5%, and conferred significant resistance in 3 of 4 populations. QFhs.nau-2DL reduced DON 6.7% on average and conferred significant resistance in 2 of 4 populations. The combination of Fhb1 and QFhs.nau-2DL resistance reduced DON 25.5% across all populations. Double resistant lines had significantly reduced DON compared to double susceptible lines in 3 populations. Backcross derived progeny were planted in replicated yield trials (2011 and 2012) and in a scab nursery in 2012. Several top yielding lines performed well in the scab nursery, with acceptable DON concentrations, even though the average effect of either QTL in this population was not significant. Population selection is often viewed as an "all or nothing" process: if the average resistance level is insufficient, the population is discarded. These results indicate that it may be possible to find rare segregants which combine scab resistance, superior agronomic performance and acceptable quality even in populations in which the average effect of the QTL is muted or negligible.
在美国，小麦赤霉病（FHB）主要由禾谷镰刀菌Schwabe [有性型：玉蜀黍赤霉Gibberella zeae Schwein.（Petch）]引起，是小麦（普通小麦Triticum aestivum L.和硬粒小麦T. durum L.）最具毁灭性的病害之一。受感染的籽粒通常被脱氧雪腐镰刀菌烯醇（DON）污染，这是一种严重的霉菌毒素。小麦赤霉病抗性育种面临的挑战是将抗性与优良的农艺和品质特性相结合。外来的数量性状位点（QTL）被广泛用于提高小麦赤霉病抗性。成功与否取决于通过回交或杂交导入QTL的遗传背景；QTL的表达无法预测。在本研究中，将4个几乎没有或完全没有赤霉病抗性的高产软红冬小麦育种系分别与一个供体亲本（VA01W - 476）杂交，该供体亲本在两个QTL（Fhb1位于3BS染色体和QFhs.nau - 2DL位于2DL染色体）上带有抗性等位基因，以产生回交和F2后代。对F2个体进行基因分型，并根据一个或两个QTL上抗性等位基因的有无将其分为4组。在两年时间里评估了这些QTL在降低F2衍生系的赤霉病评级、发病率、指数、严重程度、镰刀菌损伤籽粒（FDK）和DON方面的有效性。Fhb1使DON平均降低了17.5%，并在4个群体中的3个群体中表现出显著抗性。QFhs.nau - 2DL使DON平均降低了6.7%，并在4个群体中的2个群体中表现出显著抗性。Fhb1和QFhs.nau - 2DL抗性的组合使所有群体中的DON降低了25.5%。在3个群体中，双抗性品系的DON含量相比双感病品系显著降低。回交衍生后代于2011年和2012年进行了重复产量试验，并于2012年种植在赤霉病圃中。尽管该群体中任一QTL的平均效应不显著，但有几个高产系在赤霉病圃中表现良好，DON浓度可接受。群体选择通常被视为一个“非此即彼”的过程：如果平均抗性水平不足，该群体就会被淘汰。这些结果表明，即使在QTL平均效应不明显或可忽略不计的群体中，也有可能找到兼具赤霉病抗性、优良农艺性能和可接受品质的罕见分离个体。
