Successful sexual reproduction in flowering plants depends on the accurate timing of flowering. One environmental signal that controls flowering is day length. Short-day plants like rice promote flowering by detecting short-day photoperiods. Yet, at the northern extremes of its cultivation, rice experiences long-day photoperiods, which makes long-day flowering agronomically important in these regions. Now, Komiya and co-workers reveal a gene network that regulates long-day flowering in rice (see ). The researchers investigated flowering times in plants with mutations in the homologues of genes that control flowering time in Arabidopsis (a long-day plant) and assayed the expression of rice genes involved in flowering in these mutant rice plants. From their findings, the researchers propose that regulators of the flowering-promoting hormone RICE FLOWERING LOCUS T 1 (RFT1) - both positive (such as Ehd1, a rice-specific floral inducer, and OsMADS50, a homologue of Arabidopsis SOC1, which functions upstream of Ehd1) and negative (e.g. phyB, a plant photoreceptor gene) - form a gene network that regulates long-day flowering in rice.
