Crop hybrid technologies have contributed to the significant yield improvement worldwide in the past decades. However, designing and maintaining a hybrid production line has always been complex and laborious. Now, researchers in China have developed a new system combining CRISPR-mediated genome editing with other approaches that could produce better seeds compared with conventional hybrid methods and shorten the production timeline by 5 to 10 years. The study appears July 8 in the journal Molecular Plant.
 
Hybrids are preferred over purebreds in crop production. Crossing two genetically distant plant varieties often gives rise to progeny with superior traits compared with the parents. The offspring tend to have higher yields and better disease tolerance. This phenomenon is called heterosis, or hybrid vigor.
 
"But current hybrid methods are very time consuming and cumbersome," says senior author Chuanxiao Xie at the Chinese Academy of Agricultural Sciences.
 
For example, the first step to produce a hybrid is to find or make a type of parent plant carrying a mutation, so that it does not produce viable pollen. This is to avoid self-crossing and ensure most of the parent plants become fertilized by a different variety. But the progeny needs to be fertile in order to self-cross to produce more of itself and plants to be used as the parent. Scientists would cross the sterile plant with another that is genetically fertile to restore the plant's sterility and make hybrid seeds. Constructing a production cycle like this is vital in building an efficient seed production line in the field.
 
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