Development of transgenic male-sterile rice by using anther-specific promoters identified by comprehensive screening of the gene expression profile database ‘RiceXPro’

Because genomic selection is designed for the population breeding of allogamous species, a successive outcrossing system is required for efficient use of genomic selection in autogamous crops, such as Oryza sativa L. (rice). Transgenic and dominant male-sterility is a suitable tool for efficient outcrossing of autogamous crops. Though there have been some reports of dominant male-sterile rice developed using transgenic technology, the flowering habit was substandard. Here, to isolate promoters that, when linked to a lethal gene, induce dominant male-sterility while retaining a good flowering habit, we identified 38 candidate genes with anther-specific expression by using the ‘RiceXPro’ database. We then evaluated the abilities of the near-upstream regions of these genes to induce male-sterility when linked to the lethal gene barnase and introduced into the rice cultivar ‘Nipponbare’. Seven of the 38 promoters induced clear dominant male-sterility; promoters expressed in the later stage of anther development induced male-sterility while retaining better flowering habits when compared to ones expressed in the early stage. These seven promoters could potentially be used to facilitate development of an efficient outcross-based breeding system in rice.