Synergistic regulation of rice heading date and some agronomic traits by Ghd7 and DTH8

Objective  Heading date is an important agronomic trait in rice, which determines suitable cultivated areas and seasons of rice varieties. Ghd7 and DTH8 are two key heading date genes in rice, comprehensively discovering their genetic interaction, expression regulation, and effects on agronomic traits are important for variety breeding, improvement of adaptability and yield of rice.

Method  In this study, we bred a Ghd7/DTH8 digenic segregating population in the non-functional hd1 and prr37 background from the progeny of the hybrid rice ‘Ningyou 1179’ by molecular marker-assisted selection. Heading date, expression of the downstream genes (Ehd1, Hd3a, RFT1), and some agronomic traits were investigated.

Result  Under natural long day and natural short day conditions, either Ghd7 or DTH8 independently repressed the expression of Ehd1, Hd3a and RFT1genes, and delayed heading. Both Ghd7 and DTH8 could significantly promoted plant height, number of primary branches, number of secondary branches, spikelets of main panicle and 1000-grain weight. The Ghd7/DTH8 combination strongly suppressed the expression of the Ehd1-Hd3a/RFT1 pathway, and largely delayed heading. It also played a significant role to promote some agronomic traits, including plant height, number of primary branches, number of secondary branches, spikelets of main panicle and 1000-grain weight.

Conclusion  Ghd7/DTH8 synergistically represses the expression of the florigen genes, suppresses heading, and positively regulates some yield-related traits regardless of day-length, which is of great value for high yield breeding and genetic improvement of rice.