Os01g0919400

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OsSPS1 is a gene encoding sucrose phosphate synthase(SPS) and is a menber of the sucrose phosphate synthase gene family in rice(OsSPSs).

Annotated Information

Function

  • OsSPS1 is a gene encoding sucrose phosphate synthase(SPS). SPS catalyzes the conversion of fructose 6-phosphate and UDPglucose into sucrose 6-phosphate, and it is generally considered to be the rate-limiting enzyme in sucrose synthesis. OsSPS1 is one of the 5 isogenes encoding SPS in the rice genome and and plays a dominant role in sucrose synthesis among them[1].
  • The suppression of OsSPS1 shortens the plant length of rice seedlings[2], and the locus of OsSPS1 appears to coincide with the quantitative trait locus(QTL)for plant height[3].
  • Sucrose synthesis via OsSPS1 is essential in pollen germination in rice[4].

Mutation

Figure 1. SPS activity of Koshihikari and NIL-SPS1 during the transplanting, panicle formation, heading, and mid-ripening stages[5].
  • An NIL of rice (O. sativa L.) was generated in the process of developing chromosome segment substitution lines (CSSLs). The NIL-SPS1 carries a chromosome segment containing OsSPS1 of Kasalath on chromosome 1 in the genetic background of Koshihikari[5].

1.Figure 1. shows the SPS enzyme activities in the source leaf blades of Koshihikari and NIL-SPS1 at different developmental stages. The SPS activity in NIL-SPS1 was 30% and 59% higher than that in Koshihikari at the transplanting and panicle formation stages, respectively. However, at later developmental stages, the SPS activity in NIL-SPS1 leaves did not differ significantly from that of Koshihikari[5].

2.The plant height of NIL-SPS1 tended to be higher than that of Koshihikari throughout the measurement period, particularly after heading (Figure 2A). In contrast, tiller number in NIL-SPS1 tended to be lower than that in Koshihikari, but the difference was not significant(Figure 2B)[5].

Figure 2. Growth analysis of Koshihikari and NIL-SPS1. (A) Plant height of Koshihikari and NIL-SPS1. (B) Tiller number of Koshihikari and NIL-SPS1[5].


3.To clarify the yield characteristics of NIL-SPS1 in comparison with Koshihikari, data on the yield and yield components obtained in 2009, 2010, and 2012 were combined and analyzed statistically (Table 1)[5].

Table 1. Yield and yield components of Koshihikari and NIL-SPS1[5].

4.Since NIL-SPS1 exhibited a higher spikelet number per panicle in comparison with Koshihikari, we further compared the panicle architecture of Koshihikari and NIL-SPS1. Panicles were separated into primary and secondary rachis branches, and the number of each rachis branch, percentage of ripened grain, and single-grain weight were measured (Table 2)[5].

Table 2. Panicle architecture of Koshihikari and NIL-SPS1[5].

5.To investigate the ripening pattern of spikelets within a panicle, all spikelets were classified into 4 groups based on their positions and relative densities, and the weight of each spikelet was measured. Figure 3. shows the frequency of distribution of the spikelet weight in each of the 4 groups. On the primary rachis branch, the frequency of unripened grain in NIL-SPS1 was not different from that in Koshihikari. However, on the secondary rachis branch, the frequency of unripened grain at 50–80% in NIL-SPS1 was much higher than that in Koshihikari[5].

Figure 3. Distribution of spikelet weight of the Koshihikari and NIL-SPS1[5].

6.Figure 4. shows the changes in the dry weight of the aboveground parts of Koshihikari and NIL-SPS1 from the heading stage to maturity stage[5].

Figure 4. Aboveground biomass accumulation of Koshihikari and NIL-SPS1 after heading[5].


  • A chemically inducible gene expression system was used on OsSPS1. Inducible gene suppression works with an RNAi cassette and this cassette targets OsSPS1. The inducer is β-estradiol. The seeds of the transgenic plants were sown on the MS agar plates containing 30 μM of β-estradiol and grown for a week. In two of the three independent transgenic lines that were examined, the transcript levels of OsSPS1 in the leaf blades of the β-estradiol-treated plants were significantly less than the levels in the control plants (Fig. 5A). Concomitantly, the shoot length of the β -estradiol-treated plants was shorter than that of the control plants (Fig. 5B). In another experiment, the induced seedlings were transplanted into plastic pots filled with soil and were further grown for four weeks. During this period, 100 μM of β-estradiol containing 0.02% Tween-20 was sprayed onto the terrestrial portions of the plant parts every week (three times in total). Again, the OsSPS1 mRNA levels in the leaf blades decreased significantly in two of the three transgenic lines (Fig. 6A). In the leaf blades of the induced plants, the molar ratio of sucrose to starch decreased significantly when compared to the uninduced control plants (Fig. 6B)[6].
Figure 5.  Effects of β-estradiol on the transcript levels of OsSPS1 in the leaf blades (A) and plant lengths (B) of the inducible RNAi transgenic plants[6].
Figure 6. Effect of β-estradiol on transcript levels of OsSPS1 (A) and the molar ratio of sucrose to starch (B) in the leaf blades of the inducible RNAi transgenic plants[6].



Expression Pattern

Figure 9. Diurnal patterns of the promoter activities of OsSPS1 under light/dark cycles [7].
  • Expression analysis revealed that OsSPS1 is preferentially expressed in the source tissue, particularly in leaf blades, and it plays a dominant role in sucrose synthesis in the source leaf blades among the 5 isogenes for SPS[1].
  • The promoter activities of sucrose phosphate synthase gene in rice, OsSPS1, is controlled by light and circadian clock, but not by sucrose[7]. The promoter activities of OsSPS1 is low during the dark period and increased rapidly after the onset of the light period. While the promoter activity of OsSPS1 decreased gradually during the day and remained low through out the night(Figure2A)[7].

Subcellular localization

Knowledge Extension

  • Sucrose phosphate synthase(SPS,EC2.3.1.14)catalyzes the conversion of fructose-6-phosphate and UDP-glucose into sucrose-6-phosphate and isknown to be the major rate-limiting enzyme insucrose biosynthesis in plants.
  • plant SPS genes are clustered into four groups(groupsA,B,C, andD),based on their amino acid sequences. Rice has five SPS genes, OsSPSs, classified into four groups: OsSPS8, OsSPS1, OsSPS11, and OsSPS2 and OsSPS6 in groupsA,B,C,andD,respectively.

Labs working on this gene

  • Bio ResearchLaboratory,ToyotaMotorCorporation,Toyota,Aichi,Japan
  • LaboratoryofCropScience,GraduateSchoolofAgriculturalandLifeSciences,TheUniversityofTokyo,Bunkyo-ku,Tokyo,Japan
  • NAROAgriculturalResearchCenter,Joetsu,Niigata,Japan
  • Center forGeneResearch,NagoyaUniversity,Chikusa-ku,Nagoya,Japan
  • Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo-ku, Tokyo 113-8657, Japan
  • Toyama Prefectural Agricultural, Forestry & Fisheries Research Center, Toyama, Toyama 939-8153, Japan
  • NARO Agricultural Research Center, Joetsu, Niigata 943-0193, Japan
  • Graduate School of Science and Technology, Niigata University, Ikarashi, Nishi-ku, Niigata 950-2181, Japan
  • Bio Research Laboratory, Toyota Motor Corporation, 1 Toyota-cho, Toyota, Aichi 471-8572, Japana

References

  1. 1.0 1.1 Okamura, M., Aoki, N., Hirose, T., Yonekura, M., Ohto, C., Ohsugi, R., 2011. Tissue specificity and diurnal change in gene expression of the sucrose phosphate synthase gene family in rice. Plant Sci. 181, 159–166.
  2. Hirose,T.,Mizutani,R.,Mitsui,T., and Terao,T.(2012).Achemically inducible gene expression system and its application to inducible gene suppression in rice. PlantProd.Sci. 15, 73–78.
  3. Ishimaru,K.,Ono,K.,andKashiwagi,T. (2004). Identification of a new gene controlling plant height in rice using the candidate-gene approach. Planta 218, 388–395.
  4. Hirose T, Hashida Y, Aoki N, Okamura M, Yonekura M, Ohto C, Terao T, Ohsugi R. Analysis of gene-disruption mutants of a sucrose phosphate synthase gene in rice, OsSPS1, shows the importance of sucrose synthesis in pollen germination. Plant Sci. 2014 Aug;225:102-6. doi: 10.1016/j.plantsci.2014.05.018. Epub 2014 Jun 2. PubMed PMID: 25017165.
  5. 5.00 5.01 5.02 5.03 5.04 5.05 5.06 5.07 5.08 5.09 5.10 5.11 5.12 Hashida Y, Aoki N, Kawanishi H, et al. A near isogenic line of rice carrying chromosome segments containing OsSPS1 of Kasalath in the genetic background of Koshihikari produces an increased spikelet number per panicle[J]. Field Crops Research, 2013, 149: 56-62.
  6. 6.0 6.1 6.2 Hirose T, Mizutani R, Mitsui T, et al. A chemically inducible gene expression system and its application to inducible gene suppression in rice[J]. Plant Production Science, 2012, 15(2): 73-78.
  7. 7.0 7.1 7.2 Yonekura M, Aoki N, Hirose T, Onai K, Ishiura M, Okamura M, Ohsugi R, Ohto C. The promoter activities of sucrose phosphate synthase genes in rice, OsSPS1 and OsSPS11, are controlled by light and circadian clock, but not by sucrose. Front Plant Sci. 2013 Mar 1;4:31. doi: 10.3389/fpls.2013.00031. eCollection 2013. PubMed PMID: 23460029; PubMed Central PMCID: PMC3585450.

Structured Information