Abstract：
Tan spot, caused by the necrotrophic fungal pathogen Pyrenophora tritici-repentis (Ptr), is an important disease of durum and common wheat worldwide. Compared with common wheat, less is known about the genetics and molecular basis of tan spot resistance in durum wheat. We evaluated 510 durum lines from the Global Durum Wheat Panel (GDP) for sensitivity to the necrotrophic effectors (NEs) Ptr ToxA and Ptr ToxB and for reaction to Ptr isolates representing races 1 to 5. Overall, susceptible durum lines were most prevalent in South Asia, the Middle East, and North Africa. Genome-wide association analysis showed that the resistance locus Tsr7 was significantly associated with tan spot caused by races 2 and 3, but not races 1, 4, or 5. The NE sensitivity genes Tsc1 and Tsc2 were associated with susceptibility to Ptr ToxC- and Ptr ToxB-producing isolates, respectively, but Tsn1 was not associated with tan spot caused by Ptr ToxA-producing isolates, which further validates that the Tsn1-Ptr ToxA interaction does not play a significant role in tan spot development in durum. A unique locus on chromosome arm 2AS was associated with tan spot caused by race 4, a race once considered avirulent. A novel trait characterized by expanding chlorosis leading to increased disease severity caused by the Ptr ToxB-producing race 5 isolate DW5 was identified, and this trait was governed by a locus on chromosome 5B. We recommend that durum breeders select resistance alleles at the Tsr7, Tsc1, Tsc2, and the chromosome 2AS loci to obtain broad resistance to tan spot.
摘要：
棕褐色斑点,由坏死性真菌病原体pyrenophoratriticiss（Ptr）引起，是世界范围内硬粒和普通小麦的重要病害。与普通小麦相比，对硬粒小麦抗tan斑的遗传学和分子基础知之甚少。我们评估了来自全球硬粒小麦小组（GDP）的510条硬粒线对坏死因子（NEs）PtrToxA和PtrToxB的敏感性，以及对代表种族1-5的Ptr分离株的反应。总的来说,易感硬粒系在南亚最普遍，中东,和北非。全基因组关联分析显示，抗性基因座Tsr7与种族2和3引起的棕褐色斑点显着相关，但与种族1、4或5无关。NE敏感性基因Tsc1和Tsc2与产生PtrToxC和PtrToxB的分离株的敏感性相关，分别,但是Tsn1与产生PtrToxA的分离株引起的棕褐色斑点无关，这进一步验证了Tsn1-PtrToxA相互作用在硬粒中的棕褐色斑点发育中没有重要作用。染色体臂2AS上的独特基因座与种族4引起的棕褐色斑点有关，种族4曾被认为是无毒的。鉴定出一种新性状，其特征是黄萎病不断扩大，导致由产生PtrToxB的种族5分离株DW5引起的疾病严重程度增加，这个性状受5B号染色体上的一个基因座控制。我们建议硬粒育种者在Tsr7，Tsc1，Tsc2和染色体2AS基因座上选择抗性等位基因，以获得对棕褐色斑点的广泛抗性。
