Popular Science | How do “three wild grasses” become “a bowl of noodles”? ——A conversation with wheat breeding expert Yang Wuyun

Wheat is the most widely planted grain crop in the world, with a cultivation history of more than 10,000 years. However, the wheat we see today is no longer what it originally looked like.

"The origin and evolution of modern wheat is a coincidental and complex process, which has undergone two cases of distant hybridization," said Yang Wuyun, deputy director and researcher of Sichuan Academy of Agricultural Sciences and director of the Key Laboratory of Wheat Biology and Genetic Breeding in Southwest China of the Ministry of Agriculture and Rural Affairs.

More than 10,000 years ago, two species, one called Urartu wheat and the other Aegilops spelta, naturally hybridized to form tetraploid wheat used to make pasta. About 7,000 years ago, tetraploid wheat naturally hybridized with another species called Aegilops tauschii in nature, and its chromosomes automatically doubled, forming hexaploid wheat, the ancestor of modern bread wheat.

"Only by studying the genetic and biological characteristics of wheat can we better guide the breeding of new wheat varieties." Yang Wuyun said that now scientists can simulate the evolutionary process of wheat, hybridize different tetraploid wheats and different aestivums, synthesize new artificial synthetic wheat, and then use it as a bridge to introduce excellent genes from wheat ancestors with rich genetic diversity into modern wheat, thereby breeding new wheat varieties.

In 1995, Yang Wuyun took advantage of the opportunity of training at the International Maize and Wheat Improvement Center to bring back a batch of synthetic wheat resources containing Aegilops tauschii. At that time, breeders around the world had high hopes for synthetic wheat gene resources, but no success had been achieved.

"It contains genetic resources of Aegilops tauschii, which is very wild and has many traits that are unfavorable to breeding, such as loose plant shape, high plant height, and hard shells that are difficult to thresh. Therefore, it cannot be directly used in breeding."

Yang Wuyun hybridized the synthetic wheat he brought back with Sichuan wheat, and after multiple generations of identification, he finally developed the first breakthrough wheat variety in the world, "Sichuan Wheat 42". Sichuan Wheat 42 is highly resistant to stripe rust, has good stability, wide adaptability, excellent quality and good comprehensive traits. In 2003 and 2004, it passed the national and Sichuan provincial variety approval committees respectively, and was recommended as a new wheat variety to be promoted in Sichuan Province and the whole country.

"The yield of Sichuan wheat 42 increased by 17% in national regional trials and 30% in Sichuan provincial trials compared to the control varieties. When applied in large-scale production, it can increase the yield by about 100 kilograms per mu. Sichuan wheat 42 is now the backbone parent of Sichuan wheat breeding, and more than 40 varieties have been bred using it," said Yang Wuyun.

In the process of cultivating Sichuan Wheat 42, Yang Wuyun also combined his years of breeding practice experience to summarize a set of efficient synthetic wheat breeding utilization strategies - "large population limited backcrossing method". It can be used not only in wheat breeding, but also in other crop breeding.
"Now our research team has collected a large number of tetraploid wheat and Aegilops tauschii, and is synthesizing a large number of new artificial synthetic wheat. These materials are like our own children, and there must be good things in them." Talking about future goals, Yang Wuyun said that the first is to achieve high and stable yields, the second is to achieve green production, disease resistance, stress resistance, and less use of pesticides, and the third is to cultivate diversified varieties such as strong gluten, weak gluten, or medium-strong gluten to meet market demand at different levels.

"Wild resources are good, but they also have many bad things. We need to improve them through advanced technology so that we can better utilize their genetic resources on a larger scale to serve our modern breeding." Yang Wuyun said.

Producer | Zhan Zhao Cheng Weihong

Reporter | Song Yajuan, Xie Yun, Xiao Chunfang

Videographer | Xiao Chunfang and Li Jin

Coordination | Xu Qin