Abstract
Psathyrostachys huashanica Keng, a wild relative of common wheat with many desirable traits, is an invaluable source of genetic material for wheat improvement. Few wheat–P. huashanica translocation lines resistant to powdery mildew have been reported. In this study, a wheat–P. huashanica line, E24-3-1-6-2-1, was generated via distant hybridization, ethyl methanesulfonate (EMS) mutagenesis, and backcross breeding. A chromosome karyotype of 2n = 44 was observed at the mitotic stage in E24-3-1-6-2-1. Genomic in situ hybridization (GISH) analysis revealed four translocated chromosomes in E24-3-1-6-2-1, and P. huashanica chromosome-specific marker analysis showed that the alien chromosome fragment was from the P. huashanica 4Ns chromosome. Moreover, fluorescence in situ hybridization (FISH) analysis demonstrated that reciprocal translocation had occurred between the P. huashanica 4Ns chromosome and the wheat 3D chromosome; thus, E24-3-1-6-2-1 carried two translocations: T3DS·3DL-4NsL and T3DL-4NsS. Translocation also occurred between wheat chromosomes 2A and 4A. At the adult stage, E24-3-1-6-2-1 was highly resistant to powdery mildew, caused by prevalent pathotypes in China. Further, the spike length, numbers of fertile spikelets, kernels per spike, thousand-kernel weight, and grain yield of E24-3-1-6-2-1 were significantly higher than those of its wheat parent 7182 and addition line 24-6-3-1. Thus, this translocation line that is highly resistant to powdery mildew and has excellent agronomic traits can be used as a novel promising germplasm for breeding resistant and high-yielding cultivars.
Highlights
Wheat (Triticum aestivum L.) is one of the most widely used agricultural crop species worldwide and serves as a staple food supply for at least one-third of the global population (Yang et al, 2016)
We developed a novel wheat–P. huashanica translocation line (E24-3-1-6-2-1) that is highly resistant to powdery mildew
Two of the signals were emitted from nearly 2/3 of the wheat chromosome, obviously covering the long arm and partial short arm of the chromosome connected by the centromere, while two of the signals were emitted from nearly half of the wheat chromosome, clearly covering the short arm (Figure 2B); these results suggested that chromosome segments of P. huashanica had been translocated into the wheat chromosome
Summary
Wheat (Triticum aestivum L.) is one of the most widely used agricultural crop species worldwide and serves as a staple food supply for at least one-third of the global population (Yang et al, 2016). Fungicides are often used to control powdery mildew, but their widespread application has been hindered by high cost, the development of pathogen resistance, and environmental impacts (Khong et al, 2012). Breeding resistant cultivars is an effective and environmentally sound method to control powdery mildew (Tan et al, 2018). Powdery mildew has become a widespread disease in major wheat production areas of China, resulting in severe reductions in yield and quality (He et al, 2015). It is necessary to exploit new gene sources for resistance to powdery mildew and incorporate these genes into wheat. By introducing genetic components of wild relatives into common wheat, distant hybridization is an effective method for producing new resistant germplasm and broadening genetic diversity (Lin et al, 2017)
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