J Integr Plant Biol. ›› 2021, Vol. 63 ›› Issue (5): 913-923.DOI: 10.1111/jipb.13013

• Photosynthesis and Crop Physiology • Previous Articles     Next Articles

Global analysis of CCT family knockout mutants identifies four genes involved in regulating heading date in rice

Jia Zhang1,2, Xiaowei Fan1, Yong Hu1, Xiangchun Zhou1, Qin He1, Liwen Liang1 and Yongzhong Xing1*   

  1. 1National Key Laboratory of Crop Genetic Improvement, Huazhong Agricultural University, Wuhan 430070, China
    2College of Life Science, Jiangxi Normal University, Nanchang 330022, China

    *Correspondence: yzxing@mail.hzau.edu.cn
  • Received:2020-04-22 Accepted:2020-09-03 Online:2020-09-05 Published:2021-05-01

Abstract: Many genes encoding CCT domain‐containing proteins regulate flowering time. In rice (Oryza sativa), 41 such genes have been identified, but only a few have been shown to regulate heading date. Here, to test whether and how additional CCT family genes regulate heading date in rice, we classified these genes into five groups based on their diurnal expression patterns. The expression patterns of genes in the same subfamily or in close phylogenetic clades tended to be similar. We generated knockout mutants of the entire gene family via CRISPR/Cas9. The heading dates of knockout mutants of only 4 of 14 genes previously shown to regulate heading date were altered, pointing to functional redundancy of CCT family genes in regulating this trait. Analysis of mutants of four other genes showed that OsCCT22, OsCCT38, and OsCCT41 suppress heading under long‐day conditions and promote heading under short‐day conditions. OsCCT03 promotes heading under both conditions and upregulates the expression of Hd1 and Ehd1, a phenomenon not previously reported for other such genes. To date, at least 18 CCT domain‐containing genes involved in regulating heading have been identified, providing diverse, flexible gene combinations for generating rice varieties with a given heading date.

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