On March 2, the Wheat Research Institute of Sichuan Agricultural University/provincial ministry jointly established the State Key Laboratory of Discovery and Utilization of Crop Gene Resources in Southwest China, the Center for Excellence in Molecular Cell Science of the Chinese Academy of Sciences, and the University of California, Davis. The mechanism of the relationship between wheat grain color and ear germination resistance has laid a foundation for the analysis of the genetic mechanism of wheat ear germination characteristics and the breeding of white-skin resistant ear germination wheat. The relevant research results were published online in”New Phytologist” magazine.
Spike germination is the phenomenon that mature but unharvested grains of gramineous crops such as barley, sorghum, rice, etc. germinate on the ear under high humidity conditions. Wheat ear germination seriously affects the yield and quality of wheat. The Huanghuai wheat region, the winter wheat region in Southwest my country, the middle and lower reaches of the Yangtze River and other wheat regions are areas with frequent and serious damage to ear germination. Especially in 2016 and 2018, the outbreak of wheat spikes in Jiangsu, Anhui, Sichuan, Hubei, Henan, Xinjiang and other provinces caused a significant decline in wheat yield and quality. Wheat grains come in a variety of colors. White-skin and red-skin wheat are mainly used for production. White-skin wheat is more popular among farmers and enterprises because of its thin skin, high endosperm content and high flour extraction rate. But as early as more than 100 years ago, Nilsson-Ehle discovered that white-skin wheat is more prone to ear sprouting. A lot of evidence later showed that the color of wheat seed coat is closely related to the degree of ear sprouting, and white-skin wheat is more prone to ear sprouting.
According to Wang Jirui, the researchers analyzed the association analysis of 717 Chinese local wheat and 502 wheat varieties in the world’s main wheat-producing regions and the RILs population of the offspring of synthetic wheat After mapping the ear germination resistance gene, it was found that the wheat grain color regulator Myb10-D may be related to the ear germination resistance gene PHS-3D (QPHS.sicau-3D). Subsequently, the researchers identified that PHS-3D is located in a 2.4Mb presence/deletion variant (PAV) region of the wheat 3D chromosome, which is widely distributed in the natural population of wheat. By integrating the results of multiple omics analysis such as genome resequencing, transcriptome, metabolome of resistant materials, and functional analysis of PHS-3D transformed materials, it is clear that PHS-3D is encoded by the Myb10-D transcription factor that controls the color of the grain. Myb10-D achieves”one cause and multiple effects” by simultaneously regulating the flavonoid metabolism pathway (color gene R) and ABA synthesis pathway (the anti-sprouting gene PHS-3D). PHS-3D is combined with the SMRE element in the -192 to -199 region of the NCED promoter of the rate-limiting enzyme of ABA synthesis to positively regulate its expression and achieve the effect of increasing the concentration of ABA during seed development. The team also determined that white grain wheat generally lacks the 2.4Mb region of the 3D chromosome that contains the Myb10-D gene. Therefore, this study clarified the internal relationship between the Myb10-D transcription factor and the simultaneous regulation of wheat grain color and germination rate, and provided a new idea for the next step in the breeding of white-grain-resistant and ear-sprouting wheat.
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Sichuan Agricultural University doctoral students Lang Jing, Fu Yuxin, and graduate doctor Zhou Yong are the co-first authors, and Professor Wang Jirui is the corresponding author. The research was supported by the National Key Research and Development Program, the National Natural Science Foundation of China, the Sichuan Science and Technology Project, and the Sichuan Agricultural University Double Branch Program.
full text link:https://nph.onlinelibrary.wiley.com/doi/abs/10.1111/nph.17312