Abstract
Zhengmai 7698 is an elite winter wheat variety widely cultivated in the Southern regions of the Yellow-Huai River Valley of China. Here, we report the molecular markers used for breeding Zhengmai 7698 and the genome composition of this cultivar revealed using genome-wide SNPs. A total of 26 DNA markers derived from the genes controlling gluten protein quality, grain hardness, flour color, disease resistance, or pre-harvesting sprouting resistance were used during breeding. Consequently, Zhengmai 7698 had strong gluten, high grain hardness index, white flour color, and high levels of resistance to powdery mildew, stripe rust infections, and pre-harvesting sprouting. Using genome complexity reduction, 28,996 high-quality SNPs distributed on 21 wheat chromosomes were identified among Zhengmai 7698 and its three parental lines (4B269, Zhengmai 9405 and Zhoumai 16). Zhengmai 7698 shared 12,776, 14,411 and 16,085 SNPs with 4B269, Zhengmai 9405 and Zhoumai 16, respectively. Thus, the contributions of 4B269, Zhengmai 9405 and Zhoumai 16 to the genome of Zhengmai 7698 were comparable. Interestingly, Zhengmai 7698 had 307 unique SNPs that are absent in all three parents. We suggest that molecular markers facilitate selection of a wheat cultivar with multiple elite traits. Analysis of genome composition with SNPs may provide useful clues for further dissecting the genetic basis of improved wheat performance.
Highlights
Zhengmai 7698 is an elite winter wheat variety widely cultivated in the Southern regions of the YellowHuai River Valley of China
Molecular markers of stripe rust resistance were combined with field inoculation of strong virulent races (e.g., CY32, CY33, G22-9, G22-14, SU4, SU5) for resistance identification, and stripe rust resistance was obtained by pyramiding Yr9 and YrZH84
The powdery mildew resistance genes were combined with natural infection in the Powdery Mildew Disease Nursery, the Yuanyang test site of the Wheat Research Institute, Henan Academy of Agricultural Sciences, where high incidence of powdery mildew was observed
Summary
Zhengmai 7698 is an elite winter wheat variety widely cultivated in the Southern regions of the YellowHuai River Valley of China. 28,996 high-quality SNPs distributed on 21 wheat chromosomes were identified among Zhengmai 7698 and its three parental lines (4B269, Zhengmai 9405 and Zhoumai 16). Several problems have been identified in the current wheat breeding including lack of understanding contribution of each parental line to their progenies, the genes underlying important agronomic traits as well as lack of cultivar-specific markers for identification. Studies using high-density SNPs to examine the genomic origin of widely grown cultivars and the genetic contribution of their parental lines are lacking. Zhengmai 7698 yield could reach 11,287.5 kg/ha in a test field spot[8] setting a new yield record for high-quality strong-gluten wheat cultivars in China In recent years, this cultivar has become an important wheat breeding parent in the Huanghuai wheat production area. Systematic studies of specific detection markers associated with superior agronomic traits of Zhengmai 7698 are lacking
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