Objective Breeding aromatic rice restorer line with validated high alkali spreading value (ASV) and aroma-enhancing molecular markers was investigated.

Methods On the F₆ restorer lines derived from crossing Minghui 164/Nongxiang 21 and Shuhui 498/Nongxiang 21, molecular markers ZiS_1_ALK and FMbadh2-E7 were used to identify and confirm the target genotype. Restorer lines with confirmed phenotype and agronomic traits were crossed with sterile lines to secure the new breed for certification at regional trials.

Result ZiS_1_ALK effectively distinguished the genetic material that carried high or low ASV. Due possibly to artificial selection, relatively few high-ASV lines were obtained from the advanced-generation hybrids of the low-ASV female parent Minghui 164 and the high-ASV male parent Nongxiang 21. Trait identifications based on FMbadh2-E7 and morphological characteristics were highly agreeable, as indicated by 92.3% and 94.1% of the progenies of the badh2-carrying hybrids generated from the two combinations indeed displayed the characteristic aromatic quality. Consequently, 6 restorer lines containing the target genes were comprehensively evaluated agronomically and selected Minghui 6559, which also bore grains of high length-to-width ratio. Subsequently, the hybrids derived from it, Fuxingyou 6559 and Mingxiangyou 6559, were granted the Guangxi Province and the National Crop Variety Certificates.

Conclusion The molecular markers, ZiS_1_ALK and FMbadh2-E7, could be employed to accurately identify aromatic rice varieties with high ASV for breeding. As a result, Minghui 6559 was thus obtained and proven to be an outstanding restorer line for further development of desirable new breeds.