The Innovation Team of Soil-Plant Interactions of the Institute of Agricultural Resources and Regional Planning (IARRP) of the Chinese Academy of Agricultural Sciences (CAAS) has recently elaborated upon and analyzed the domestication and selection of yield-regulating genes in maize and rice. Relevant results were published in the form of Spotlight in "Trends in Genetics".

According to Professor Wu Qingyu, human ancestors domesticated wild species of corn and rice into modern cultivated varieties over thousands of years. The increase in grain number per ear is one of the most obvious changes caused by domestication.

Recently, an important study by Chinese scientists found that the gene KRN2, which regulates the number of grains in maize and rice, was convergently selected during domestication. KRN2 alters grain number in these two crops by regulating inflorescence meristem development. However, unlike other inflorescence meristem regulatory genes, knockout of KRN2 did not lead to negative phenotypes such as the massive proliferation of inflorescence, but significantly increased the number of grains and yield. By investigating a large number of germplasm resources, no nonsense mutant alleles of this gene were found in natural populations. The authors explore this in depth.

By analyzing the recombination and mutation frequency of the location of the gene, the authors found that this segment is not a 'mutation desert', so it is speculated that although the nonsense mutation allele of the gene may have appeared, it was not preserved for various reasons.

The paper also predicted the function of KRN2 protein in combination with previous research work. KRN2 encodes a protein with multiple WD40 domains, forming a propeller-like structure, and its structurally similar proteins also include the well-known heterotrimeric G protein beta subunit.

Previously, Wu's research group, Professor David Jackson's research group from the Cold Spring Harbor Laboratory, USA, and Professor Xu Fang from Shandong University had discovered that the maize G beta protein plays an important role in regulating meristem development and immunity (PNAS 2020, 117:1799). Therefore, the authors speculate that KRN2 may also function in immune responses, and propose that proximity labeling techniques such as Turbo ID can help to mine the interacting proteins of KRN2, thereby uncovering the hidden functions of this protein.

The paper also pointed out that phenotypic identification of different alleles of the gene in multiple genetic backgrounds will help to further understand the function of the gene and fully unleash its application potential.

Xiao Bing, a doctoral student at the IARRP, and Li Pei, a doctoral student jointly trained by Shenyang Agricultural University, are the co-first authors of the paper. Professor Wu Qingyu is the corresponding author of the paper.

The research was funded by the National Natural Science Foundation of China, the Key R&D Program and the Innovation Project of the Chinese Academy of Agricultural Sciences.

Paper link: https://doi.org/10.1016/j.tig.2022.06.002