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Annotated Information


Rice PAP2 encodes MADS34, a grass-specific SEPALLATA(SEP) subfamily MADS domain protein.PAP2 functions as a positive regulator of SM identity[1].PAP2 also functions as a suppressor of the extra elongation of glumes[2].In addtion,PAP2 activated in the meristem at phase transition and function in specifying IM identity in rice[3].


  • Figure 1 shows the Phenotype of the wild type and pap2-1 mutant in panicle development.the arrangement of lateral organs, such as rachis branches and spikelets, was disordered and the panicle became irregularly denser, in sharp contrast to the well-defi ned phyllotaxy of the wild-type panicle ( Fig. 1B–D ).A signifi cant increase in the number of primary rachis branches per panicle was observed in pap2-1 , indicating that the IM activity was maintained longer in pap2-1 than in the wild-type ( Fig. 1F ).In the wild-type panicle, 31.0 % of lateral organs produced in the primary rachis branches grow as secondary rachis branches, whereas 70.8 % become secondary branches in pap2-1 ( Fig. 1G )[3].
Fig1.Phenotype of the wild type and the pap2-1 mutant in panicle development
  • Figure 2 shows the Phenotype of the wild and pap2-1 mutant in spikelet development.(A–C) shows the Spikelets in the wild-type (A) and pap2-1 (B, C).(D–F)shows SEM analysis of the spikelet of wild-type (D) and pap2-1 (E, F).(G and H) shows the number of rudimentary glumes (G) and sterile lemmas (H) in the wild-type and pap2-1 .Approximately 60 % of the spikelets in a pap2-1 panicle exhibited elongated rudimentary glumes, and 40 % of them developed an ectopic filamentous organ.Approximately 13 % of the sterile lemmas elongated to about half the size of the lemma, 65 % grew to a similar size and 23 % grew longer[3].
Fig 2.Phenotype of wild type and pap2-1 in spikelet development


PAP2 expression starts the earliest among the five SEP genes, and a low but signifi cant level of PAP2 mRNA was detected in the infl orescence meristem, in branch meristems immediately after the transition, and in glume primordia, consistent with its role in the early development of spikelet formation.


OsMADS34 is a member of the MADS-box gene family that regulates many aspects of plant growth and development. PAP2/OsMADS34 is a type II MADS-box gene (there are > 44 known type II MADS-box genes), a member of the SEPALLATA ( SEP ) subfamily,PAP2/OsMADS34 belong to the LOFSEP subgroup( Fig. 3)[3]

Fig 3.Phylogenetic tree of SEP genes in plants

Knowledge Extension

  • Plants progress through distinct developmental phases in their life cycles. The transition from vegetative to reproductive growth, generally called flowering,is vital for reproductive success. Flowering occurs in response to environmental and developmental signals, such as daylength, plant age, and temperature . Multiple flowering signals are eventually transmitted to the shoot apical meristem (SAM)[3].
  • The aerial part of a plant is generated by the SAM, which produces leaves during vegetative development. Upon transition to reproductive development, the SAM converts into an inflorescence meristem (IM) and starts to generate components of the inflorescence. Development of the IM is variable depending on species, leading to formation of species-specificinflorescence architecture. The conversion from the vegetative SAM to the IM is less well understood at the molecular level than events such as flowering time control, floral meristem specification, and flower development.Several genes show a dramatic change in their expression patterns in the meristem at phase transition [4][5][6][7][8]. This reflects a global change in meristem gene expression that is associated with the establishment of IM identity [9][10].

Labs working on this gene

  • Graduate School of Agriculture and Life Sciences, University of Tokyo,Yayoi, Bunkyo, Tokyo 113-8657, Japan
  • National Institute of Agrobiological Sciences, Tsukuba, Ibaraki 305-8602, Japan
  • Crop Development Division, National Agricultural Research Center, National Agriculture and Food Research Organization,Jo-etsu, Niigata 943-0193, Japan
  • Rice Research Division, National Institute of Crop Science, National Agriculture and Food Research Organization,Tsukuba 305-8518, Japan
  • Research Institute for Bioresources, Okayama University, Kurashiki, Okayama, 710-0046 Japan
  • Plant Functional Genomics Laboratory (PFGL), Molecular Genetics Department, National Institute of Agrobiological Science (NIAS),Kannondai 2-1-2, Tsukuba, Ibaraki, 305-8602 Japan



Park, S.J., Jiang, K., Schatz,et al.Rate of meristem maturation determines inflorescence architecture intomato[J]. Proc. Natl. Acad. Sci. USA ,2012,109: 639–644.

Structured Information

  1. 1.0 1.1 Kobayashi, K., Maekawa, M., Miyao, A., Hirochika, H., andKyozuka.PANICLE PHYTOMER2 (PAP2), encoding a SEPALLATA subfamily MADS-box protein, positively controls spikelet meristem identity in rice[J}.Plant Cell Physiol,2010, 51: 47–57.
  2. 2.0 2.1 Gao, X., Liang, W., Yin, C., Ji, S., Wang, H., Su, X., Guo, C., Kong, H., Xue, H., and Zhang, D.The SEPALLATA-like gene Os-MADS34 is required for rice inflorescence and spikelet development[J}.PlantPhysiol,2010,153: 728–740.
  3. 3.0 3.1 3.2 3.3 3.4 3.5 Kaoru Kobayashi,a Naoko Yasuno,a Yutaka Sato,et al.Inflorescence Meristem Identity in Rice Is Specified by Overlapping Functions of Three AP1/FUL-Like MADS Box Genes and PAP2, a SEPALLATA MADS Box Gene[J].The Plant cell,2012,24: 1848–1859.
  4. 4.0 4.1 Cardon, G.H., Höhmann, S., Nettesheim,et al.Functional analysis of the Arabidopsis thaliana SBP-box gene SPL3: A novel gene involved in the floral transition[J].Plant J,1997,12: 367–377.
  5. 5.0 5.1 Hempel, F.D., Weigel, D., Mandel, M.A.,et al.Floral determination and expression of floral regulatory genes in Arabidopsis[J].Development,1997,124: 3845–3853.
  6. 6.0 6.1 Lee, H., Suh, S.S., Park,et al.The AGAMOUS-LIKE 20 MADS domain protein integrates floral inductive pathways in Arabidopsis[J].Genes Dev,2000, 14: 2366–2376.
  7. 7.0 7.1 Samach, A., Onouchi, H., Gold, S,et al.Distinct roles of CONSTANS target genes in reproductive development of Arabidopsis[J].Science,2000, 288: 1613–1616.
  8. 8.0 8.1 Torti, S., Fornara, F., Vincent, C.,et al.Analysis of the Arabidopsis shoot meristem transcriptome during floral transition identifies distinct regulatory patterns and a leucine-rich repeat protein that promotes flowering[J].The Plant cell,2012,24: 444–462.
  9. 9.0 9.1 Shimada, S., Ogawa, T., Kitagawa, S.,et al.A genetic network of flowering-time genes in wheat leaves, in which an APETALA1/FRUITFULL-like gene, VRN1,is upstream of FLOWERING LOCUS T[J].Plant J,2009,58: 668–681.
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