Os08g0509600

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OsSPL14, a member of the SQUAMOSA PROMOTER BINDING PROTEIN-LIKE (SPL) genes[1], and plays an important role in controlling rice plant architecture as well as yield [2].

Annotated Information

Function

Figure 1. OsSPL14 regulates plant morphology and influences rice grain yield(from reference)[2].
  • The rice gene OsSPL14 plays an important role in controlling rice plant architecture as well as yield. OsSPL14 encodes a SQUAMOSA promoter-binding-like (SPL) protein, as a gene that can affect plant architecture[2]. Figure 1 shows that OsSPL14 regulates plant morphology and influences rice grain yield. (a) Classic rice plants are highly tillered with relatively small panicles. (b) In contrast, the new plant type (NPT) architecture is characterized by fewer tillers and more productive panicles. Normally, OsmiR156 induces cleavage of OsSPL14 transcripts, leading to a repression of OsSPL14 activity. However, mutation of an OsmiR156 binding site within OsSPL14 increases the levels of OsSPL14 and results in rice plants with fewer tillers but more productive panicles and consequently higher grain yields[2].
  • Higher expression of OsSPL14 in the reproductive stage promotes panicle branching and higher grain yield in rice. OsSPL14 controls shoot branching in the vegetative stage and is affected by microRNA excision[3].

Mutation

Figure 2. OsSPL14 structure and the mutation site in SNJ.(from reference)[4].
Figure 3. Effects of the point mutation.(from reference)[4].
  • Figure 2 shows OsSPL14 structure and the mutation site in SNJ. The white boxes represent the 5′and 3′untranslated regions, the black boxes represent the coding sequences and lines between boxes represent introns. The red asterisk indicates the OsmiR156 target site[4].
  • Previous studies suggested that 11 OsSPL genes were putative targets of OsmiR156, a member of an miRNA family consisting of 19–25-base-pair noncoding single-stranded regulatory RNAs. Bioinformatic analysis indicated that OsSPL14 has the OsmiR156 complementary site in the coding region[4].
  • Figure 3b, indicating that perturbing the OsmiR156 cleavage of OsSPL14 even without changing the resulting amino acid sequence leads to alteration of the plant architecture in SNJ. Figure 3c and 3d, suggesting that the point mutation may also perturb the OsmiR156-directed translation repression of OsSPL14. Therefore, the point mutation in the OsmiR156-complementary site of OsSPL14 perturbs the OsmiR156-directed transcriptional cleavage and translation repression in rice[4].
  • Jiao et al. demonstrate that a point mutation in OsSPL14 perturbs OsmiR156-directed regulation of OsSPL14, generating an‘ideal’ rice plant with a reduced tiller number, increased lodging resistance and enhanced grain yield[4].

Expression

Figure 4. Expression pattern of OsSPL14(from reference)[1].
  • Expression patterns of OsSPL14 and OsmiR156 in various rice organs revealed by real-time PCR and miRNA gel blot analyses showed that OsSPL14 was highly expressed in the culm and shoot apex, which is complementary with the expression pattern of OsmiR156 in vivo. Consistently, overexpression of OsmiR156 resulted in a substantial decrease in OsSPL14 transcripts, whereas the interruption of OsmiR156 led to a marked increase in OsSPL14 transcripts. These results indicated that OsSPL14 was regulated by the OsmiR156-directed cleavage in vivo[4].
  • It has previously been reported that OsSPL14 is expressed in shoot apices and young panicles of rice. Luo et al. confirm that OsSPL14 is expressed in the leaf primordia but is excluded from the meristematic cells[1]. Kotaro Miura et al. determined that OsSPL14 expression is regulated by post-transcriptional gene silencing, as they demonstrated that the expression of OsSPL14 is controlled by OsmiR156 [3].
  • Figure 4 shows expression pattern of OsSPL14. (A, B, D, E, G and H) RNA in situ hybridization with an OsSPL14 probe. (C, F and I) RNA in situ hybridization using an OSH1 probe. (A) The shoot apical meristem at transition. (B) and (C) A panicle at the secondary branch initiation stage. (D) Transverse view of the panicle at the secondary branch initiation stage. (E) and (F) Immature spikelets. (G) Axillary meristem. (H) and (I) Axillary meristem at a later stage. SAM, shoot apical meristem; br, bract primordia; fm, flower meristem; le, lemma; pa, palea; sl, sterile lemma; rg, rudimentary glumes; AM, axillary meristem; lp, leaf primordia. Asterisks indicate the primary and secondary branch meristems[1].

Evolution

Figure 5. Phylogenetic tree and homology analysis of SPL proteins(from reference) [3].
  • Phylogenetic analysis indicated that the OsSPL gene at Os08g0509600 is categorized as OsSPL14 and is conserved in sorghum, wheat, maize and Arabidopsis thaliana. Figure 5 shows the phylogenetic tree and homology analysis of SPL proteins. (a) Phylogenetic tree of SPL proteins among rice, sorghum, wheat, maize, and Arabidopsis. OsSPL14/WFP is highlighted by the red rectangle. (b) Homology analysis of SPL domains of the WFP clade. The SBP-domain includes the Zn-1, Zn-2, and NLS domains[3].
  • SPL protein are plant-specific transcription factors containing a highly conserved DNA-binding domain called an SBP-box. The founder members of the SPL family, SBP1 and SBP2, were identified in Antirrhinum majus as proteins that bind to a sequence motif present in the promoter of SQUAMOSA (SQUA), the MADS-box gene which specifies flower meristem identity. SPL genes are widely conserved in both dicots and monocots. In maize, a few SPL genes have been identified, including liguleless1 (LG1), teosinte glume architecture 1 (tga1) and tasselsheath4 (TSH4)[1].
  • The rice OsSPL14 gene is the closest homolog of the Arabidopsis SPL9 and SPL15 genes and one of the 11 OsmiR156-targeted SPL genes of rice[1].

Localization

Figure 6. Subcellular localization and transactivation analysis of OsSPL14 protein(from reference)[3].
Figure 7. subcellular localization of the OsSPL14-GFP fusion protein(from reference)[4].
  • Subcellular localization analysis using green fluorescent protein (GFP) fusion OsSPL14 proteins detected the GFP signal localized to nuclei (Figure 6a). Additionally, analysis using the yeast one-hybrid system showed that the OsSPL14 protein had transcription-activating abilities (Figure 6b). Figure 6 shows subcellular localization and transactivation analysis of OsSPL14 protein. (a) Subcellular localization of OsSPL14 was analyzed using the GFP fusion OsSPL14 protein driven by the 35S promoter. Nuclei were stained with DAPI. (b) The full-length cDNA of OsSPL14 and SK1-Full, as a positive control, were fused to the GAL4-DNA binding domain. The pGBKT7-vector is the negative control[3].
  • OsSPL14 is localized to the nucleus (Figure 6 and 7), consistent with a role as a transcription factor[4].

Knowledge Extension

  • SPL genes, which share a highly conserved DNA-binding domain (the SBP domain), represent a family of plant-specific transcription factors that are involved in the regulation of flowering time, phase change, leaf initiation and other developmental processes in higher plants. In the rice genome, there are 19 SPL genes and OsSPL14 (also known as IPA1 and WFP) is most similar to Arabidopsis SPL9, which has been suggested to be involved in regulating plastochron length and leaf size[4].
  • The SPL genes make up a plant-specific multigene family of transcription factors that can play roles in regulating plant morphology and the decision to flower[2].
  • Some of the SPL genes are controlled by miR156 that controls phase transitions in plants. In Arabidopsis, 10 out of 16 SPL genes broadly control developmental transition and are targets of miR156. The expression level of miR156 is high in the early stage of shoot development, and decreases with time. Accordingly, the mRNA level of miR156-targeted SPL genes gradually increases as development proceeds, in agreement with its role in the temporal control of shoot development. In Arabidopsis, the targets of miR156 are divided into two classes, one containing SPL3, SPL4 and SPL5, encoding small proteins, and the other containing genes encoding longer proteins. Generally, genes in both groups are involved in the control of temporal development; in particular, in phase transition and flowering. Among members of the second group, SPL9 and SPL15 are expressed during the vegetative phase and function in the control of leaf initiation[1].

Labs working on this gene

  • State Key Laboratory of Plant Genomics and National Center for Plant Gene Research, Institute of Genetics and Developmental Biology, Chinese Academy of Sciences, Beijing 100101, China
  • Graduate School of Agriculture and Life Sciences, University of Tokyo, Yayoi, Bunkyo, Tokyo 113-8657, Japan
  • Department of Bioscience, Fukui Prefectural University, 4-1-1 Matsuoka Kenjyojima, Eiheiji-cho, Yoshida-gun, Fukui 910-1195, Japan
  • Bioscience and Biotechnology Center, Nagoya University, Nagoya, Aichi 464-8601, Japan

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 1.6 Luo L, Li W, Miura K, Ashikari M, Kyozuka J. Control of tiller growth of rice by OsSPL14 and Strigolactones, which work in two independent pathways[J]. Plant & cell physiology, 2012,53(10):1793-1801.
  2. ↑ 2.0 2.1 2.2 2.3 2.4 Springer N. Shaping a better rice plant[J]. Nat Genet, 2010,42(6):475-476.
  3. ↑ 3.0 3.1 3.2 3.3 3.4 3.5 Miura K, Ikeda M, Matsubara A, Song X-J, Ito M, Asano K, et al. OsSPL14 promotes panicle branching and higher grain productivity in rice[J]. Nat Genet, 2010,42(6):545-549.
  4. ↑ 4.0 4.1 4.2 4.3 4.4 4.5 4.6 4.7 4.8 4.9 Jiao Y, Wang Y, Xue D, Wang J, Yan M, Liu G, et al. Regulation of OsSPL14 by OsmiR156 defines ideal plant architecture in rice[J]. Nat Genet, 2010,42(6):541-544.

Structured Information

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