Abstract:

Indica-japonica untypical plants will be produced in the process of indica hybrid seeds production when japonica pollens are mixed, and this type of untypical plants often displays the character of abnormal heading (commonly known as Daqingke in China), and results in purity decrease of hybrid rice, which ultimately affects grains yield. In order to avoid the occurrence of abnormal heading due to improper choosing of parents in mating groups or poor isolation in seed production in japonica regions, finding out proper molecular markers that could accurately distinguish indica from japonica may provide a reference for breeding and hybrid seed production. In this study, the three-line indica hybrid rice‘Yuetai A’/‘R2020’and untypical plants with character of abnormal heading in the field were used as experimental materials. Polymorphic SSR markers between two parents were used to analyze genotype of the untypical plants, and eighteen pairs of specific InDel markers were used to identify the indica-japonica attributes. The results showed that there were twenty-two loci differences between the male sterile line ‘Yuetai A’ and the restorer line ‘R2020’ among the forty-eight pairs of SSR markers recommended by the industry standard "Protocol for identification of rice varieties-SSR Marker Method" (NY/T 1433-2014); eight untypical plants all showed out-crossing type bands under six pairs of SSR markers (RM72, RM85, RM224, RM253, RM424 and RM481); the results of thirteen pairs of indica japonica specific InDel markers further proved that these eight out-crossing plants were all derived from hybridization of indica-japonica subspecies. Thirteen pairs of InDel markers for identification of indica-japonica attributes were preliminarily selected in this study, which provided a molecular basis for avoiding the generation of untypical plants of abnormal heading.

Key words: rice, indica-japonica untypical plants, abnormal heading, InDel marker, indica-japonica identification