In many Asian countries, rice crops are prone to destruction by flooding. Most cultivars of rice, Oryza sativa, die after a week of complete submergence, but a few strains can survive a couple of weeks under water due to a major quantitative trait locus called Submergence 1 (Sub1). A detailed study of the Sub1 genes has now identified one, Sub1A, as the primary determinant of tolerance to submergence. The introduction of Sub1A into a widely grown Asian rice cultivar increases its survival rate in flood conditions without sacrificing its high yield and other good properties.