Marker-Assisted Backcrossing to Develop an Elite Cytoplasmic Male Sterility Line in Rice

Cytoplasmic male sterility (CMS) is a cornerstone of hybrid production in many crops. In three-line hybrid systems, use of CMS, maintainer, and fertility restorer lines is necessary for production of hybrid seeds. Limited resources of CMS and low variation of CMS lines cause genetic vulnerability to pathogens. Therefore, diversifying the CMS sources is indispensible for a sustainable production system of hybrid seed. In this study, we attempted for the first time to transfer CMS into maintainer line Yosen B in restrict ed generations using the marker-assisted backcrossing (MABC) method. The resultant F1 hybrid of IR68897 A/Yosen B cross was backcrossed to Yosen B, and CMS plants in each backcross generation (from BC1F1 to BC3F1) were selected based on phenotyping test and MABC. Molecular assessment of backcross