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- A rice Dwarf 1 gene was identified by using a map-based cloning strategy. Its recessive mutant allele photoperiod-sensitive dwarf 1(Psd) confers a dwarf phenotype.It was shown to be essential for cell division and elongation as well as the inflorescence development, which is regulated by day-length dependent signals.
- Plant height is an important agronomic trait for crop architecture and yield. Dwarf mutants in plants are crucial for elucidating regulatory mechanisms for plant growth and development. This character is also favored in breeding. Dwarf mutants have been isolated in many species and have been extensively analyzed for their mode of inheritance and their response to plant hormones. While these phenotypes induced by a recessive allele (d1) of the Dwarf(D1) gene are thought to reflect aberrant physiological and biochemical pathways in plant growth and development. The rice d1 mutant was classified as gibberellin-insensitive, though most known factors determining plant height function in gibberellin or brassinosteroid or signal transduction.
- It is expressed in elongating stem, vegetative sheath and young inflorescence.
(1)Expression analysis of flowering-related genes, Hd3a, RFT1, Ehd1, Ghd7and DTH8 in the Psd1 mutant grown under LD(long day) condition. No obvious expression change of these genes was detected in the mutant and wild-type plants, so Psd1 mutation involves the pathways for the inflorescence development and stem elongation, but not those for the cegetative to inflorescence phase transition.(Fig.2)
(2)Psd1-related genetic network is regulated by day-length dependent signals.
Wide Type VS Mutant
- we observed that the plant height of Psd1 mutant was increased when the plants were grown from August to October, the SD season with day-length of 12.9-11.6h. This suggested that the Psd1 phenotype might be affected by day-length, and the dwarf phenotype is suppressed under SD conditions. Therefore, Psd1 is a novel photoperiod-sensitive dwarf mutant.(Fig.3)
- There is a big difference with the length of the third-leaf sheath between Psd1 and ZH11 plants.(Table.1)
- Average cell number and size are of obvious difference. Transverse sections of elongated internodes of Psd1 and ZH11 showed that the structure of parenchyma cells and vascular bundles of Psd1 was different from ZH11, the average number of cells and the cell size of the internodes were also different. All together, cell division and elongation were impaired in the Psd1 mutant.
Responses to GA and BR
Psd1mutant respond to exogenous bioactive GA to a similar degree as wild-type rice, but exogenous GA could not rescue the dwarf phenotype. Also, the dwarf phenotype could not be rescued by exogenous BR.(Fig.4) Moreover, the sheaths of Psd1 seedings could elongate to the similar length as ZH11 under complete darkness, a phenotype different from that of BR-related mutants, in which sheaths could not elongate in the dark. These characterization suggest that Psd1 may not be deficient in the bio synthesis and perception of GA or BR.
Labs working on this gene
- Identification and characterization of the Psd1 mutant
- responses of Psd1 mutant to GA and BR
- Photoperiod sensitivity tests
- Linkage analysis and gene mapping
- RNA isolation and quantitative RT-PCR analysis
- Expression analysis of flowering-related genes in the mutant.
- Riqing Li, Jixing Xia, Yiwei Xu, Xiucai Zhao, Yao-Guang Liu, Yuanling Chen. Characterization and genetic mapping of a Photoperiod-sensitive dwarf1 locus in rice(Oryza sativa L.)[J] Theor Appl Genet, 2014, 127: 241-250.
- Mits unagas, Tashiro T, Yamaguti J. Rice gibberellin-insensitive dwarf mutant gene Dwarf 1 encodes the α-subunit of GTP-binding protein.[J] PNAS, 1999, 96: 10284-10289.