Volume 32, No 10, Oct 2022

ISSN: 1001-0602 
EISSN: 1748-7838 2018 
impact factor 17.848* 
(Clarivate Analytics, 2019)

Volume 32 Issue 10, October 2022: 931-945

ORIGINAL ARTICLES

A spontaneous thermo-sensitive female sterility mutation in rice enables fully mechanized hybrid breeding

Haoxuan Li^1,2,3 , Chenjiang You⁴ , Manabu Yoshikawa⁵ , Xiaoyu Yang^6,7 , Haiyong Gu⁸ , Chuanguo Li⁸ , Jie Cui⁶ , Xuemei Chen^4,* , Nenghui Ye^3,* , Jianhua Zhang^1,2,* , Guanqun Wang^1,2,*

¹Department of Biology, Hong Kong Baptist University, Hong Kong, China
²School of Life Sciences and State Key Laboratory of Agrobiotechnology, The Chinese University of Hong Kong, Hong Kong, China
³Southern Regional Collaborative Innovation Center for Grain and Oil Crops in China, College of Agriculture, Hunan Agricultural University, Changsha, Hunan, China
⁴Department of Botany and Plant Sciences, Institute of Integrative Genome Biology, University of California, Riverside, CA, USA
⁵Division of Plant and Microbial Sciences, Institute of Agrobiological Sciences, National Agriculture and Food Research Organization, 2-1-2 Kannondai Tsukuba, Ibaraki, Japan
⁶Guangdong Provincial Key Laboratory for Plant Epigenetics, College of Life Sciences and Oceanography, Shenzhen University, Shenzhen, Guangdong, China
⁷College of Horticulture Science and Engineering, Shandong Agricultural University, Taian, Shandong, China
⁸The Rice Research Institute, Guangdong Academy of Agricultural Sciences, Guangzhou, Guangdong, China
Correspondence: Xuemei Chen(xuemei.chen@ucr.edu)Nenghui Ye(nye@hunau.edu.cn)Jianhua Zhang(jzhang@hkbu.edu.hk)Guanqun Wang(gqwang@link.cuhk.edu.hk)

Male sterility enables hybrid crop breeding to increase yields and has been extensively studied. But thermo-sensitive female sterility, which is an ideal property that may enable full mechanization in hybrid rice breeding, has rarely been investigated due to the absence of such germplasm. Here we identify the spontaneous thermo-sensitive female sterility 1 (tfs1) mutation that confers complete sterility under regular/high temperature and partial fertility under low temperature as a point mutation in ARGONAUTE7 (AGO7). AGO7 associates with miR390 to form an RNA-Induced Silencing Complex (RISC), which triggers the biogenesis of small interfering RNAs (siRNAs) from TRANS-ACTING3 (TAS3) loci by recruiting SUPPRESSOR OF GENE SILENCING (SGS3) and RNA-DEPENDENT RNA POLYMERASE6 (RDR6) to TAS3 transcripts. These siRNAs are known as tasiR-ARFs as they act in trans to repress auxin response factor genes. The mutant TFS1 (mTFS1) protein is compromised in its ability to load the miR390/miR390* duplex and eject miR390* during RISC formation. Furthermore, tasiR-ARF levels are reduced in tfs1 due to the deficiency in RDR6 but not SGS3 recruitment by mTFS1 RISC under regular/high temperature, while low temperature partially restores mTFS1 function in RDR6 recruitment and tasiR-ARF biogenesis. A miR390 mutant also exhibits female sterility, suggesting that female fertility is controlled by the miR390-AGO7 module. Notably, the tfs1 allele introduced into various elite rice cultivars endows thermo-sensitive female sterility. Moreover, field trials confirm the utility of tfs1 as a restorer line in fully mechanized hybrid rice breeding.

https://doi.org/10.1038/s41422-022-00711-0

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