Golden Hull: A Potential Biomarker for Assessing Seed Aging Tolerance in Rice

Seed aging is a complex process that involves various physiological and biochemical changes leading to a decline in seed viability during storage. However, the specific biomarkers for assessing the degree of seed aging in rice remain elusive. In this study, we isolated a golden hull mutant, gh15, from the indica rice Z15 by employing a radiation mutagenesis technique. Compared with the wild type (WT) Z15, the mutant gh15 displayed a golden hue in the hull, stem, and internodes, while no significant differences were observed in the key agronomic traits. A genetic analysis showed that the gh15 phenotype is regulated by a single recessive gene, which possibly encodes cinnamyl alcohol dehydrogenase OsCAD2. Significant differences of seed aging tolerance were observed between gh15 and WT after six months of natural storage and artificial aging treatment, with gh15 exhibiting a markedly lower aging tolerance compared to the WT. Haplotype assays indicated that the Hap2 of OsCAD2 was significantly associated with the dark coloration of the hull and lower seed aging tolerance. The molecular marker of OsCAD2 associated with seed color was explored in rice. These findings demonstrate that the golden hull serves as a potential biomarker for the rapid assessment of seed aging tolerance in rice.