Chinese scientists found a "switch" to regulate the germination of rice and wheat ears

After research, the team of Chu Chengcai and Gao Caixia of the Institute of Genetics and Developmental Biology of the Chinese Academy of Sciences recently found two "switches" that regulate the germination of rice and wheat ears, including SD6, a key gene that negatively regulates seed dormancy, and ICE2
, a gene that positively regulates seed dormancy.
The researchers believe that the combination of the two genes is expected to provide a solution
for large-scale agricultural losses caused by seed ear germination.
The results were published online Dec.
6 in the journal
Nature Genetics.

In the process of crop domestication, due to more consideration of high yield, high quality, pest resistance and stress tolerance, the retention of moderate dormancy of seeds is often neglected, resulting in ear germination of many crops such as rice and wheat (if the seed ripening period before harvest can not be harvested in time in the rain, some grains often germinate on the ear), which seriously affects the yield and quality of crops, causing huge economic losses, and even affecting the next season's sowing
phenomenon 。 Therefore, it is crucial to find the key genes that control seed dormancy such as rice and wheat, elucidate the molecular physiological mechanism of seed dormancy regulation, and tap their excellent allele variations, which are crucial
to solve the germination disaster of rice and other crops.

The scientific research team of the Institute of Genetics and Development, Chinese Academy of Sciences, successfully cloned a key gene SD6 to control rice seed dormancy from a strongly dormant rice variety by constructing a chromosomal single-segment substitution line using the strongly dormant rice variety Casalas and the weakly dormant rice variety Haru Nippon, and confirmed that SD6 negatively regulates rice seed dormancy
.
By screening SD6 interacting proteins, the team found another rice transcription factor, ICE2, which is regulating seed dormancy
.

The research team found that the SD6/ICE2 molecular module is a seed dormancy regulator that can sense the ambient temperature: under normal temperature conditions, SD6 gene expression is maintained at a high level and exerts its function, while ICE2 gene function is significantly inhibited, thereby promoting seed germination.
Under low temperature conditions, the function of SD6 gene is significantly inhibited, and the expression of ICE2 gene is upregulated, so as to exert its function, so that the seeds remain dormant
.
That is, by sensing the temperature changes of the external environment, SD6/ICE2 further controls the content of plant hormone abscisic acid in seeds, thereby regulating the dormancy intensity of seeds and ensuring that they adapt to the natural season change and reproduce successfully
.

The research team improved the SD6 gene in the rice varieties Tianlong 619, Wuyun Japonica 27 and Huaidao No.
5 through gene editing technology, and found that the improved rice material suffered continuous rainy weather during the harvest period, and its ear germination was significantly improved
.
The research team's improvement of the TaSD6 gene of the wheat variety Kenong 199 can also greatly improve the germination resistance of wheat ears, indicating that the SD6 gene is conserved in the function of controlling seed dormancy in rice and wheat
.
These research results show that SD6 has important application value
in the germination resistance breeding improvement of rice and wheat ear.

(Edited by Li Chuang)