Os01g0323600

OsSAMS1, 2 and 3 are essential for histone H3K4me3 and DNA methylation to regulate gene expression related to flowering in Oryza sativa.

Annotated Information

Function

• OsSAMS1, 2 and 3 are essential for histone H3K4me3 and DNA methylation to regulate gene expression related to flowering in Oryza sativa.
• RNA interference (RNAi) transgenic rice with downregulated transcripts of OsSAMS1, 2 and 3 showed pleiotropic phenotypes, including dwarfism, reduced fertility, delayed germination, as well as late flowering. Delayed germination was largely rescued by application of SAM in the knockdown lines.

Expression

• OsSAMS1 was expressed abundantly in almost every tissue. OsSAMS2 was preferentially expressed in young roots and panicles. By contrast, the expression of OsSAMS3 was weak compared with OsSAMS1 (Fig. 1A).Thus, OsSAMS genes were constitutively expressed but the various homologues may have different functions during development.The double mutant containing OsSAMS1 or 2, or 3 alone no longer depended on externally added SAM when their expression was induced in the presence of galactose (Fig. 1B). Thus, OsSAMS1, 2 and 3 were all genetically complemented for the functional SAMS enzyme in the yeast double mutant in vivo. Moreover, as shown in Fig. 1B, the OsSAMS1 activity was comparable to OsSAMS2, and OsSAMS3 activity was weak.

'Fig. 1. Biochemical characterization of Oryza sativa S-adenosylmethionine synthetase (OsSAMS1, 2, 3) and expression patterns. (A) Expression profile of OsSAMS1,2, 3 in different ZH 10 organs detected by real-time RT-PCR. Error bars represent±SD. (B) OsSAMS1, 2, 3 complemented yeast sam1 sam2 double mutant W744-1A. Yeast transformants were grown as patches on uracil-less synthetic glucose media(top panel), and then were diluted and replicated to uracil-less media containing galactose (bottom panel). 1/5, 1/25 and 1/50 meant dilution ratio. W303-1A was used as WT yeast, AtSAM1 was used as a positive control.'

• Real-time RT-PCR analysis of OsSAMS1 revealed reduced expression in the transgenic lines W, M and S, by 60.4%, 4.8%, 2.6% that of the WT, respectively, and OsSAMS2 and OsSAMS3 also showed a significant decrease in expression levels (Fig. 3A). The expression of OsSAMS2 was decreased to 76.1%, 31.5% and 15.9% in the W, M and S lines.

'Fig. 3. Identification of OsSAMS1-RNAi transgenic plants. (A) Real-time RT-PCR analysis of the expression of OsSAMS1, 2, 3 genes in OsSAMS1-RNAi transgenic seedlings. Error bars represent ±SD.'

Labs working on this gene

• Research Center for Molecular and Developmental Biology, Key Laboratory of Photosynthesis and Environmental Molecular Physiology, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
• Graduate School of the Chinese Academy of Sciences, Beijing 100049, China
• National Plant Gene Research Center, Beijing 100093, China
• Key Laboratory of Molecular Biology, College of Heilongjiang Province, Heilongjiang University, Harbin 150080, China

References

• Baurle I, Dean C. The timing of developmental transitions in plants. Cell 2006;125:655–64.