小麦成株抗条锈病基因聚合体创制及其抗性表达分析

Puccinia striiformis f. sp tritici (Pst), the causal agent of wheat stripe rust (also known as yellow rust), is responsible for major yield losses in a large scale of wheat-producing areas. The most effective and environmentally friendly strategy to limit yield losses caused by Pst has been the deployment of resistance genes (Yr genes). Yr genes are divided into two general categories: seedling or all-stage resistance and adult plant resistance that is usually associated with a “partial resistance” phenotype. Wheat breeders highly pay attention to applying all-stage resistance genes in resistance breeding although this kind of resistance is usually short-lived, owing to frequent changes in the pathogen population. A possible solution for this problem is to acquire durable resistance by pyramiding adult plant resistance genes. However, related works on genetics and breeding using adult plant resistance genes are still lacking. Yr18, Yr36, and YrAS2388 are found from common wheat, Triticum turgidum ssp. dicoccoides, and Aegilops tauschii, respectively. They are important sources of partial resistance that is expressed in adult plants. Our aims in this program are: (1) to pyramid Yr36, YrAS2388, and Yr18 dispersedly existed in previously developed elite wheat lines in order to develop new elite wheat lines with all the three genes for the purpose of durable resistance breeding; (2) to transfer 0, 1, 2, or all of the 3 genes into the wheat line Sy95-71, a susceptible spreader for resistance identification of stripe rust, for the purpose of resistance genetic study. These lines with different gene combinations will be further used to investigate the interaction expression of these genes. We expect that the newly resultant germplasm and theoretical outcomes will be helpful for durable resistance genetics and breeding of wheat stripe rust.

小麦条锈病是导致小麦产量损失的一个主要世界性病害。小麦育种家注重全生育期抗性基因应用，但是条锈菌的快速变异易导致全生育期抗性丧失。聚合利用成株抗条锈病基因，培育推广抗性持久的小麦品种被广泛认为是控制条锈病的一个长效措施，但相应的遗传育种工作仍缺乏。Yr18、Yr36、YrAS2388分别来源于普通小麦（六倍体）、野生二粒小麦（四倍体）、节节麦（二倍体），它们在成株期对条锈病表现为部分抗性。本研究的目的在于：（1）以前期培育的优良新品系为基础，获得综合农艺性状优异的“Yr36+YrAS2388+Yr18”聚合体，为条锈病持久抗性育种提供优异亲本；（2）以条锈病抗性鉴定的诱发材料Sy95-71为遗传背景，将这三个基因导入，创制分别具有0个、1个、2个和3个基因的遗传研究材料，并分析这三个基因的互作表达关系。预期本研究结果可为培育持久抗条锈病的小麦新品种提供材料和理论基础。

由于条锈菌变异快，如何持续有效防控小麦条锈病是一个长期的国际性难题。聚合成株部分抗性基因，可望获得较为持久的条锈抗性，但相应育种研究工作仍缺乏。本项目通过分子标记辅助选择，聚合3个具有不同基因结构的广谱成株部分抗性基因Yr18、Yr36、YrAS2388，并导入普通小麦背景，创制出综合农艺性状优良的育种聚合体和具有相同遗传背景不同基因组合的遗传研究材料。导入YrAS2388基因育成的小麦新品种蜀麦1675高产、条锈病抗性突出，导入Yr36和Gpc-B1基因选育出优良小麦品系蜀麦1701。将“YrAS2388+Yr18+Yr36”三基因聚合在小麦品种蜀麦969、蜀麦830遗传背景，选育的高代株系高抗条锈病、综合农艺性状优，为条锈病持久抗性育种提供了新资源；以感病材料SY95-71（小麦锈病诱发材料）为遗传背景下，创制出具有不同抗病基因组合的遗传研究材料，为下一步抗病遗传机制研究提供了材料。田间抗性鉴定表明，单基因抗性Yr18 > Yr36 >YrAS2388；不同基因组合的抗性效应Yr18+YrAS2388+Yr36 > Yr18+Yr36 > Yr18+YrAS2388 > YrAS2388+Yr36；基因表达分析表明，YrAS2388介导的条锈病抗性与基因本身表达量水平有关，YrAS2388可能促进Yr36的表达，抑制Yr18表达。本研究结果证实聚合几个成株部分抗性基因可以实现全生育期完全抗性，创制的聚合体株系为持久抗条锈育种提供优异亲本和解决方案。