利用分子检测和基因编辑快速创制籼粳杂种亲和材料

Rapidly creating indica-japonica hybrid compatibility materials by molecular detection and genome editing

[目的]利用分子检测和基因编辑技术,快速精准创制籼粳人工亲和系材料,打破籼粳杂种不育,为实现远缘杂种优势利用提供新范例。[方法]本研究以优质籼稻‘黄华占’(HHZ)和优质粳稻‘中嘉8号’(ZJ8)为测试底盘,利用分子检测技术,检测HHZ和ZJ8中影响籼粳杂种不育的主效座位基因型,结合基因编辑技术,对影响HHZ与ZJ8杂种F1育性的主效座位进行基因敲除,从而快速精准创建具有高结实率的HHZ与ZJ8籼粳杂种F1。[结果]HHZ与ZJ8杂种F1表现出强大的杂种优势,但其小穗育性为半不育。根据籼粳稻亚种间杂种不育已有认知,通过分子检测,发现该杂交组合存在一个已克隆的杂种不育主效座位S5。为此,本研究利用基因编辑技术,分别敲除S5座位籼稻的杀手基因ORF5+和粳稻的帮凶基因ORF4+,与野生型相比,这些编辑材料的重要农艺性状无明显变化。但这些编辑材料分别与野生型ZJ8和HHZ杂交获得的杂种F1的小穗育性能够完全恢复到全可育。[结论]利用分子检测和基因编辑能实现籼粳杂交育种的理性设计,快速培育出籼粳亲和型材料,最大程度地保留籼粳稻遗传多样性,为突破籼粳杂种不育和实现籼粳杂种优势的充分利用提供了一种新模式。

[Objective]By molecular detection and genome editing,a rapid and precise creation of artificial hybrid-compatible lines is carried out to break the indica-japonica hybrid sterility and provide a new paradigm for realizing the utilization of indica-japonica hybrid vigor.[Method]In this study,an elite indica rice variety‘Huanghuazhan’(HHZ)and an elite japonica rice variety‘Zhongjia 8’(ZJ8)were used as test materials.The genotypes of the major indica-japonica hybrid sterility loci in HHZ and ZJ8 were detected by molecular detection.Then,the genome editing was carried out to knock out the major hybrid sterility gene(s)conferring HHZ-ZJ8 hybrid fertility,thereby rapidly and precisely creating indica-japonica hybrid F1 with high fertility.[Result]The HHZ-ZJ8 hybrid F1 plants showed strong hybrid vigor,but exhibited spikelet semi-sterility.According to genetic mechanism of intersubspecific hybrid sterility in indica and japonica rice,molecular detection revealed that one known major locus S5 exists in the HHZ-ZJ8 hybrids.Then,genome editing was used to knockout S5-ORF5+(killer gene)in HHZ and S5-ORF4+(partner gene)in ZJ8.Compared with the wild type,several important agronomic traits of these edited materials had no obvious changes.However,the spikelet fertility of the F1 plants derived from crossing these edited materials with wild type ZJ8 or HHZ were fully restored.[Conclusion]Rational design of indica-japonica hybrid breeding can be achieved by molecular detection and genome editing,enabling rapid cultivation of indica-japonica artificial hybrid-compatible lines and maximizing the retention of genetic diversity in indica and japonica rice.This study provides a new example for breaking the indica-japonica hybrid sterility and utilizing indica-japonica hybrid vigor.