Department of Plant Sciences, Crop Development Centre, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
International Maize and Wheat Improvement Center (CIMMYT), Mexico, D.F., Mexico.
PLoS One. 2018 May 10;13(5):e0197317. doi: 10.1371/journal.pone.0197317. eCollection 2018.
Widening the genetic basis of leaf rust resistance is a primary objective of the global durum wheat breeding effort at the International Wheat and Maize Improvement Center (CIMMYT). Breeding programs in North America are following suit, especially after the emergence of new races of Puccinia triticina such as BBG/BP and BBBQD in Mexico and the United States, respectively. This study was conducted to characterize and map previously undescribed genes for leaf rust resistance in durum wheat and to develop reliable molecular markers for marker-assisted breeding. Four recombinant inbred line (RIL) mapping populations derived from the resistance sources Amria, Byblos, Geromtel_3 and Tunsyr_2, which were crossed to the susceptible line ATRED #2, were evaluated for their reaction to the Mexican race BBG/BP of P. triticina. Genetic analyses of host reactions indicated that leaf rust resistance in these genotypes was based on major seedling resistance genes. Allelism tests among resistant parents supported that Amria and Byblos carried allelic or closely linked genes. The resistance in Geromtel_3 and Tunsyr_2 also appeared to be allelic. Bulked segregant analysis using the Infinium iSelect 90K single nucleotide polymorphism (SNP) array identified two genomic regions for leaf rust resistance; one on chromosome 6BS for Geromtel_3 and Tunsyr_2 and the other on chromosome 7BL for Amria and Byblos. Polymorphic SNPs identified within these regions were converted to kompetitive allele-specific PCR (KASP) assays and used to genotype the RIL populations. KASP markers usw215 and usw218 were the closest to the resistance genes in Geromtel_3 and Tunsyr_2, while usw260 was closely linked to the resistance genes in Amria and Byblos. DNA sequences associated with these SNP markers were anchored to the wild emmer wheat (WEW) reference sequence, which identified several candidate resistance genes. The molecular markers reported herein will be useful to effectively pyramid these resistance genes with other previously marked genes into adapted, elite durum wheat genotypes.
拓宽叶锈病抗性的遗传基础是国际小麦和玉米改良中心（CIMMYT）全球硬粒小麦育种工作的主要目标。北美的育种计划也紧随其后，特别是在墨西哥和美国分别出现新的叶锈菌菌株 BBG/BP 和 BBBQD 之后。本研究旨在鉴定和定位硬粒小麦中以前未描述的叶锈病抗性基因，并开发可靠的分子标记进行辅助选择育种。四个重组自交系（RIL）作图群体由抗性源 Amria、Byblos、Geromtel_3 和 Tunsyr_2 与感病系 ATRED #2 杂交构建，用于评估它们对来自墨西哥的叶锈菌菌株 BBG/BP 的反应。对宿主反应的遗传分析表明，这些基因型的叶锈病抗性基于主要的幼苗抗性基因。抗性亲本间的等位性测试表明，Amria 和 Byblos 携带等位或紧密连锁的基因。Geromtel_3 和 Tunsyr_2 的抗性也似乎是等位的。使用 Infinium iSelect 90K 单核苷酸多态性（SNP）阵列进行的混池分离分析鉴定出两个叶锈病抗性的基因组区域；一个位于 6BS 染色体上，用于 Geromtel_3 和 Tunsyr_2，另一个位于 7BL 染色体上，用于 Amria 和 Byblos。在这些区域内鉴定的多态性 SNP 被转换为竞争性等位基因特异性 PCR（KASP）分析，并用于对 RIL 群体进行基因分型。KASP 标记 usw215 和 usw218 与 Geromtel_3 和 Tunsyr_2 中的抗性基因最接近，而 usw260 与 Amria 和 Byblos 中的抗性基因紧密连锁。与这些 SNP 标记相关的 DNA 序列被锚定到野生二粒小麦（WEW）参考序列上，鉴定出了几个候选抗性基因。本文报道的分子标记将有助于有效地将这些抗性基因与其他先前标记的基因聚合到适应的、优秀的硬粒小麦基因型中。
