Identification of a Candidate Gene for the Novel Cytoplasmic Male Sterility Derived from Inter-Subspecific Crosses in Rice (<i>Oryza sativa</i> L.)

• Main Authors: Zhuo Jin, Jeonghwan Seo, Backki Kim, Seung Young Lee, Hee-Jong Koh
• Format: Article
• Language: English
• Published: MDPI AG 2021-04-01
• Series: Genes
• Subjects: cytoplasmic male sterility; <i>orf312</i>; Tetep-CMS; mitochondrial genome; mitotype-specific sequences; restorer-of-fertility
• Online Access: https://www.mdpi.com/2073-4425/12/4/590

Tetep-cytoplasmic male sterility (CMS) was developed through successive backcrosses between subspecies <i>indica</i> and <i>japonica</i> in rice (<i>Oryza sativa</i> L.), which showed abnormal anther dehiscence phenotypes. Whole genome sequencing and de novo assembly of the mitochondrial genome identified the chimeric gene <i>orf312</i>, which possesses a transmembrane domain and overlaps with two mitotype-specific sequences (MSSs) that are unique to the Tetep-CMS line. The encoded peptide of <i>orf312</i> was toxic to <i>Escherichia coli </i>and inhibited cell growth compared to the control under isopropyl-β-D-1-thiogalactopyranoside (IPTG) induction. The peptide of <i>orf312</i> contains COX11-interaction domains, which are thought to be a main functional domain for <i>WA352c</i> in the wild abortive (WA-CMS) line of rice. A QTL for <i>Rf-Tetep</i> (restorer-of-fertility gene(s) originating from Tetep) was identified on chromosome 10. In this region, several restorer genes, <i>Rf1a, Rf1b, </i>and<i> Rf4, </i>have previously been reported. Collectively, the interactions of <i>orf312</i>, a candidate gene for Tetep-CMS, and <i>Rf-Tetep</i>, a restorer QTL, confer male sterility and fertility restoration, respectively, which enables a hybrid rice breeding system. Further studies on <i>orf312</i> and isolation of <i>Rf-Tetep</i> will help to identify the underlying molecular mechanism of mitochondrial ORFs with the COX11-interaction domains.