【摘要】 由于人工驯化与现代育种操作,普通小麦(Triticum aestivum)的遗传多样性日渐狭窄,更容易受到病虫害威胁。通过远缘杂交将野生近缘种的抗病基因导入小麦,有助于拓宽小麦的遗传基础,为培育抗病品种提供新抗原。十倍体长穗偃麦草(Thinopyrum ponticum)是小麦遗传改良中应用最广泛的近缘物种之一,对小麦锈病等多种病害表现出良好的抗性。利用远缘杂交和染色体工程,创制了1份小麦-长穗偃麦草种质材料WTS135,对叶锈菌(Puccinia triticina)生理小种THTT表现出免疫。系谱分析表明,其叶锈病抗性来源于长穗偃麦草外源染色体。基因组原位杂交(GISH)-荧光原位杂交分析显示, 1对十倍体长穗偃麦草染色体替换了小麦7D染色体。液相芯片分析表明,外源染色体属于第7部分同源群,其近着丝粒区的信号密度及丰度明显较低,与GISH分析结果互相佐证,因此推测WTS135是1个7St(7D)的二体异代换系。分子标记检测显示,WTS135携带的抗病基因与已知的长穗偃麦草第7部分同源群抗叶锈病基因Lr19和Lr29不同,推测有可能为1个抗叶锈病新基因。借助Specific-locus amplified fragment sequencing技术,开发了10个长穗偃麦草特异引物,用于快速追踪WTS135中的外源染色质。表型调查显示, WTS135的产量与轮回亲本济麦22无显著差异,可直接用于小麦的抗病育种。更多还原

【Abstract】 INTRODUCTION: The genetic diversity of common wheat(Triticum aestivum) has decreased sharply due to the domestication and modern breeding operations, making it more vulnerable to the threats from pests and pathogens. Leaf rust, caused by the fungal pathogen Puccinia triticina(Pt), is a devastating disease in wheat. Over 80 leaf rust resistance(Lr) genes have been identified, with nearly half originating from wheat wild relatives. However, the rapid evolution of Pt has rendered many Lr genes ineffective against prevalent Pt races. Consequently, identifying novel sources of resistance in wild relatives of common wheat remains an urgent priority for sustainable wheat breeding. RATIONALE: As one of the most widely used relatives in the genetic improvement of wheat, decaploid Thinopyrum ponticum shows excellent resistance to multiple diseases including leaf rust. By distant hybridization and chromosome engineering, we created a wheat-Th. ponticum line WTS135. We evaluated its disease resistance with Pt race THTT, developed Th. ponticum specific markers by specific-locus amplified fragment sequencing technology and assessed its agronomic traits by phenotypic investigation. Genomic in situ hybridization(GISH)-fluorescence in situ hybridization analysis(FISH) and liquid chip analysis have been used to identify its chromosome composition. RESULTS: WTS135 is immune to the Pt race THTT. Pedigree analysis showed that this resistance originated from the exogenous chromosome of Th. ponticum. GISH-FISH analysis revealed that the wheat chromosomes 7D were replaced by the Th. ponticum-derived chromosomes. Liquid chip analysis showed that the alien chromosomes belonged to the homoeologous group 7, and the density and abundance of the signals in the peri-centromeric region were significantly lower, which was consistent with the GISH results. Therefore, it is indicated that WTS135 is a 7St(7D) disomic substitution line. After detected by the molecular markers related to known Lr genes on wheat 7D chromosome, it is speculated that WTS135 probably carries a novel resistance gene that is different from genes Lr19 and Lr29. Ten primers specific to Th. ponticum were developed to rapidly trace the exogenous chromatin in WTS135. Phenotypic investigation showed that the yield of WTS135 was not significantly different from that of the recurrent parent Jimai 22, suggesting that this line can be useful for improving disease resistance in wheat. CONCLUSION: Introducing resistance genes from wild relatives into wheat through distant hybridization can broaden the genetic base of wheat and provide new sources for breeding disease-resistant varieties. We developed a common wheat-Th. ponticum 7St(7D) substitution line, which possibly has a novel alien resistance gene and could be used in the breeding for enhancing wheat disease resistance.更多还原