Analysis of PHOTOPERIOD SENSITIVITY5 Sheds Light on the Role of Phytochromes in Photoperiodic Flowering in Rice

Publication Type:Journal Article
Year of Publication:2009
Authors:Andrés, F, Galbraith, DW, TALON, MANUEL, Domingo, C
Journal:Plant Physiology
Date Published:2009
ISBN Number:00320889
Keywords:Oryza, Oryza sativa

A great number of plants synchronize flowering with day length. In rice (Oryza sativa), photoperiod is the primary environmental cue that triggers flowering. Here, we show that the s73 mutant, identified in a y-irradiated Bahia collection, displays early flowering and photoperiodic insensitivity due to a null mutation in the PHOTOPERIOD SENSITIVITY5 (SE5) gene, which encodes an enzyme implicated in phytochrome chromophore biosynthesis. s73 mutant plants show a number of alterations in the characteristic diurnal expression patterns of master genes involved in photoperiodic control of flowering, resulting in up-regulation of the floral integrator Heading date3a (Hd3a). Early heading datel (Ehd1), an additional rice floral activator, was also highly expressed in the s73 mutant, suggesting that SE5 represses Ehd1 in wild-type plants. Silencing of Ehd1 in both Bahia and s73 backgrounds indicated that SE5 regulates Ehd1 expression. The data also indicate that SE5 confers photoperiodic sensitivity through regulation of Hdl. These results provide direct evidence that phytochromes inhibit flowering by affecting both Hd1 and Ehd1 flowering pathways.

Short Title:Plant Physiology
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