Scientists Analyze the New Mechanism of Corn Yield Regulation

On October 5th, "Nature-Communication" published online the important results of Zhang Zuxin's research group from the State Key Laboratory of Crop Genetic Improvement of Huazhong Agricultural University and Hubei Hongshan Laboratory
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The study identified a pleiotropic QTL that controls ear length, number of grains per row, number of grains per ear, and grain yield in maize, and confirmed that a key gene of ethylene biosynthesis, ZmACO2, is the functional gene of this QTL, revealing the gene for the first time A new mechanism that controls the level of endogenous ethylene biosynthesis in the inflorescence, affects the abortion rate of florets, and controls the number of grains per panicle

Maize is one of the most important cereal crops in the world.
The storage material in its grains can be used to meet the growing population’s needs for diet, industrial raw materials and biofuels.
Therefore, the genetic improvement of maize grain yield has always been well received.
Pay attention
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Through long-term genetic improvement, the number of corn per ear has been increasing, and the grain yield has been continuously improved

Breeding practice has proved that there are two ways to increase corn grain yield: First, increase the number of florets to increase the number of grains per ear under a specific planting density; second, increase the number of grains per unit area by increasing the planting density
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The former needs to improve the activity of inflorescence and floret development, and increase the number of fertile florets; the latter needs to overcome the adverse effects of dense planting conditions on floret development and fertility

However, scientists have so far known little about the genes for seed setting and kernel number per ear and their mechanism of action in the process of improving maize yield
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In the early stage, Zhang Zuxin’s team had identified a gene KNR6 involved in inflorescence differentiation, and revealed its molecular mechanism to increase grain yield by increasing the number of florets and grains per spike
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Recently, the team cloned an important gene ZmACO2 that controls the number of kernels in a corn ear.
It encodes 1-aminocyclopropane-1-carboxylic acid oxidase 2 (ACO2), which is involved in the biosynthesis of endogenous ethylene during inflorescence development
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Experimental data showed that using CRISPR-Cas9 gene editing technology to knock out the ZmACO2 gene, the endogenous ethylene biosynthesis in female inflorescences was significantly reduced, the abortion rate of female florets decreased, and the seed setting rate increased, which ultimately resulted in the number of kernels per ear of maize inbred lines Increase
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Importantly, knocking out the ZmACO2 gene can also increase the yield of hybrids by approximately 13.

Figure 1 Evaluation of yield-related traits of hybrids derived from ZmACO2 gene knockout families (photo courtesy of the research team)

The research was funded by the National Key Research and Development Program and the National Natural Science Foundation of China

Related paper information: https://doi.