Favorable QTLs from Oryza longistaminata improve rice drought resistance

Drought is the major abiotic stress to rice grain production under unpredictable changing climatic environments. Wild rice of O. longistaminata show diverse responses and strong tolerance to stress environments. In order to identify whether the O. longistaminata can improve the rice drought resistance or not, a BIL population of 143 BC₂F₂₀ lines derived from the cross between the cultivar rice 9311 and O. longistaminata were assessed under stress of 20% PEG6000.

In total, 28 QTLs related to drought resistance based on eight agronomic traits of seedlings were identified. Of which, thirteen QTLs including two QTLs for leaf drying, one QTL for leaf rolling, one QTL for leaf number, five QTLs for dry weight of root, two QTLs for dry weight of shoot, one QTL for maximum root length and two QTLs for maximum shoot length were derived from O. longistaminata. What's more, qDWR8.1 for dry weight of root was repeatedly detected and fine-mapped to an interval about 36.2 Kb. The unique allele of MH08g0242800 annotated as ATP-dependent Clp protease proteolytic subunit from O. longistaminata was suggested as the candidate gene for drought resistance. Further, six representative BIL lines were stably characterized showing significantly stronger drought resistance than 9311 based on principle component analysis, they each contained 2 ~ 5 QTLs including qDWR8.1 from O. longistaminata.

Together, our results indicate that the QTLs from O. longistaminata can effectively enhance the drought tolerance of rice, showing great potential value in breeding of elite rice varieties, which will lay a novel insight into the genetic network for drought tolerance of rice.