RT Journal Article SR Electronic T1 An Essential Role for miRNA167 in Maternal Control of Embryonic and Seed Development JF Plant Physiology JO Plant Physiol. FD American Society of Plant Biologists SP 453 OP 464 DO 10.1104/pp.19.00127 VO 180 IS 1 A1 Yao, Xiaozhen A1 Chen, Jilin A1 Zhou, Jie A1 Yu, Hanchuanzhi A1 Ge, Chennan A1 Zhang, Min A1 Gao, Xiuhua A1 Dai, Xinhua A1 Yang, Zhong-Nan A1 Zhao, Yunde YR 2019 UL http://www.plantphysiol.org/content/180/1/453.abstract AB Maternal cells play a critical role in ensuring the normal development of embryos, endosperms, and seeds. Mutations that disrupt the maternal control of embryogenesis and seed development are difficult to identify. Here, we completely deleted four MICRORNA167 (MIR167) genes in Arabidopsis (Arabidopsis thaliana) using a clustered regularly interspaced short palindromic repeats (CRISPR)/CRISPR-associated protein9 (Cas9) genome-editing technology. We found that plants with a deletion of MIR167A phenocopied plants overexpressing miRNA167-resistant versions of Auxin Response Factor6 (ARF6) or ARF8, two miRNA167 targets. Both the mir167a mutant and the ARF overexpression lines were defective in anther dehiscence and ovule development. Serendipitously, we found that the mir167a (♀) × wild type (♂) crosses failed to produce normal embryos and endosperms, despite the findings that embryos with either mir167a+/− or mir167a−/− genotypes developed normally when mir167a+/− plants were self-pollinated, revealing a central role of MIR167A in maternal control of seed development. The mir167a phenotype is 100% penetrant, providing a great genetic tool for studying the roles of miRNAs and auxin in maternal control. Moreover, we found that mir167a mutants flowered significantly later than wild-type plants, a phenotype that was not observed in the ARF overexpression lines. We show that the reproductive defects of mir167a mutants were suppressed by a decrease of activities of ARF6, ARF8, or both. Our results clearly demonstrate that MIR167A is the predominant MIR167 member in regulating Arabidopsis reproduction and that MIR167A acts as a maternal gene that functions largely through ARF6 and ARF8.