Key Laboratory of Crop Physiology, Ecology and Genetic Breeding, Ministry of Education, College of Agronomy, Jiangxi Agricultural University, 330045, Nanchang, China.
National Engineering Laboratory of Rice (Nanchang), Rice Research Institute, Jiangxi Academy of Agricultural Sciences, 330200, Nanchang, China.
BMC Plant Biol. 2022 Dec 27;22(1):612. doi: 10.1186/s12870-022-04011-y.
Phytochromes are important photoreceptors in plants, and play essential roles in photomorphogenesis. The functions of PhyA and PhyB in plants have been fully analyzed, while those of PhyC in plant are not well understood.
A rice mutant, late heading date 3 (lhd3), was characterized, and the gene LHD3 was identified with a map-based cloning strategy. LHD3 encodes phytochrome C in rice. Animo acid substitution in OsphyC disrupted its interaction with OsphyB or itself, restraining functional forms of homodimer or heterodimer formation. Compared with wild-type plants, the lhd3 mutant exhibited delayed flowering under both LD (long-day) and SD (short-day) conditions, and delayed flowering time was positively associated with the day length via the Ehd1 pathway. In addition, lhd3 showed a pale-green-leaf phenotype and a slower chlorophyll synthesis rate during the greening process. The transcription patterns of many key genes involved in photoperiod-mediated flowering and chlorophyll synthesis were altered in lhd3.
The dimerization of OsPhyC is important for its functions in the regulation of chlorophyll synthesis and heading. Our findings will facilitate efforts to further elucidate the function and mechanism of OsphyC and during light signal transduction in rice.
植物中的光敏色素是重要的光受体，在光形态建成中发挥着重要作用。PhyA 和 PhyB 的功能已在植物中得到充分分析，而 PhyC 在植物中的功能尚未得到很好的理解。
对水稻突变体晚抽穗 3 号（lhd3）进行了表征，并通过基于图谱的克隆策略鉴定了 LHD3 基因。LHD3 在水稻中编码光敏色素 C。OsphyC 中的氨基酸取代破坏了其与 OsphyB 或自身的相互作用，抑制了同源二聚体或异源二聚体形成的功能形式。与野生型植物相比，lhd3 突变体在 LD（长日）和 SD（短日）条件下均表现出开花延迟，开花时间的延迟与通过 Ehd1 途径的日照长度呈正相关。此外，lhd3 在变绿过程中表现出淡绿叶表型和较慢的叶绿素合成速率。许多参与光周期介导的开花和叶绿素合成的关键基因的转录模式在 lhd3 中发生了改变。
OsPhyC 的二聚化对于其在调节叶绿素合成和抽穗中的功能很重要。我们的发现将有助于进一步阐明 OsphyC 在水稻光信号转导中的功能和机制。
