Plant Molecular Biology

, Volume 69, Issue 3, pp 273–285 | Cite as

Functional conservation of wheat orthologs of maize rough sheath1 and rough sheath2 genes

  • Ryoko Morimoto
  • Emi Nishioka
  • Koji Murai
  • Shigeo Takumi


Maize rough sheath2 (RS2) and Arabidopsis ASYMMETRIC LEAVES1 (AS1) both encode a Myb transcription factor and repress Knotted1-type homeobox (KNOX) genes. The RS2/AS1-KNOX relationship is functionally conserved between maize and Arabidopsis. Here, we cloned wheat orthologs of RS2/AS1 and of a maize rough sheath1 (rs1) KNOX gene and named them WRS2 and WRS1, respectively. WRS1 mRNA was detected at leaf insertion points of the vegetative shoot meristem but was missing in differentiating floral organs. Conversely, WRS2 transcripts accumulated in initiating and developing floral organs. Transgenic tobacco plants expressing WRS1 showed morphological alterations typically observed due to expression of other KNOX genes. WRS2 with a deletion of the Myb domain could interact with NtPHAN to form a heterodimer, and expression of the truncated WRS2 gene conferred a dominant-negative phenotype similar to that expected and induced ectopic expression of an endogenous KNOX gene. Moreover, WRS2 expression alleviated morphological alterations in tobacco plants expressing the wheat KNOX gene. Therefore, the WRS2 gene product represses KNOX expression. These results indicate that the WRS2KNOX relationship plays a fundamentally important role in lateral organ initiation and differentiation of meristems in wheat development. The antagonistic relationship between WRS2 and KNOX around meristematic tissues has been functionally conserved during wheat evolution.


Dominant-negative Homeobox gene Ortholog Shoot apical meristem Triticum aestivum L. 



We thank C. Hirabayashi for her technical assistance, and Drs. K. Mizumoto and F. Kobayashi for helpful discussions. The EST clone (whyd13d14), and seeds of nullitetrasomics and einkorn wheat were supplied by the National BioResource Project-Wheat (Japan; This work was supported in part by a Grant-in-Aid from the Ministry of Education, Culture, Sports, Science and Technology of Japan (no. 17780005) to ST.

Supplementary material

11103_2008_9422_MOESM1_ESM.ppt (150 kb)


  1. Barton MK, Poethig RS (1993) Formation of the shoot apical meristem in Arabidopsis thaliana: an analysis of development in the wild type and in the shoot meristemless mutant. Development 119:823–831Google Scholar
  2. Baulcombe DC, Saunders GR, Bevan MW, Mayo MA, Harrison BD (1986) Expression of biologically active viral satellite RNA from the nuclear genome of transformed plants. Nature 321:446–449. doi: 10.1038/321446a0 CrossRefGoogle Scholar
  3. Bharathan G, Goliber TE, Moore C, Kessler S, Pham T, Sinha NR (2002) Homologies in leaf form inferred from KNOX1 gene expression during development. Science 296:1858–1860. doi: 10.1126/science.1070343 CrossRefPubMedGoogle Scholar
  4. Byrne ME, Barley R, Curtis M, Arroyo JM, Dunham M, Hudson A, Martienssen R (2000) Asymmetric leaves1 mediates leaf patterning and stem cell function in Arabidopsis. Nature 408:967–971. doi: 10.1038/35050091 CrossRefPubMedGoogle Scholar
  5. Chen J-J, Janssen B-J, Williams A, Sinha N (1997) A gene fusion at a homeobox locus: alterations in leaf shape and implications for morphological evolution. Plant Cell 9:1289–1304CrossRefPubMedGoogle Scholar
  6. Chuck G, Lincoln C, Hake S (1996) KNAT1 induces lobed leaves with ectopic meristems when overexpressed in Arabidopsis. Plant Cell 8:1277–1289CrossRefPubMedGoogle Scholar
  7. Jackson D, Veit B, Hake S (1994) Expression of maize KNOTTED1 related homeobox genes in the shoot apical meristem predicts patterns of morphogenesis in the vegetative shoot. Development 120:405–413Google Scholar
  8. Janssen B-J, Lund L, Sinha N (1998) Overexpression of a homeobox gene, LeT6, reveals indeterminate features in the tomato compound leaf. Plant Physiol 117:771–786. doi: 10.1104/pp.117.3.771 CrossRefPubMedGoogle Scholar
  9. Kerstetter RA, Laudencia-Chingcuanco D, Smith LG, Hake S (1997) Loss-of-function mutations in the maize homeobox gene, knotted1, are defective in shoot meristem maintenance. Development 124:3045–3054PubMedGoogle Scholar
  10. Kim M, McCormick S, Timmermans M, Sinha N (2003a) The expression domain of PHANTASTICA determines leaflet placement in compound leaves. Nature 424:438–443. doi: 10.1038/nature01820 CrossRefPubMedGoogle Scholar
  11. Kim M, Pham T, Hamidi A, McCormick S, Kuzoff RK, Sinha N (2003b) Reduced leaf complexity in tomato wiry mutants suggests a role for PHAN and KNOX genes in generating compound leaves. Development 130:4405–4415. doi: 10.1242/dev.00655 CrossRefPubMedGoogle Scholar
  12. Lincoln C, Long J, Yamaguchi J, Serikawa K, Hake S (1994) A knotted1-like homeobox gene in Arabidopsis is expressed in the vegetative meristem and dramatically alters leaf morphology when overexpressed in transgenic plants. Plant Cell 6:1859–1876CrossRefPubMedGoogle Scholar
  13. Long JA, Moan EI, Medford JI, Barton MK (1996) A member of the KNOTTED class of homeodomain proteins encoded by the STM gene of Arabidopsis. Nature 379:66–69CrossRefPubMedGoogle Scholar
  14. McHale NA, Koning RE (2004) PHANTASTICA regulates development of the adaxial mesophyll in Nicotiana leaves. Plant Cell 16:1251–1262. doi: 10.1105/tpc.019307 CrossRefPubMedGoogle Scholar
  15. Morimoto R, Kosugi T, Nakamura C, Takumi S (2005) Intragenic diversity and functional conservation of the three homoeologous loci of the KN1-type homeobox gene Wknox1 in common wheat. Plant Mol Biol 57:907–924. doi: 10.1007/s11103-005-3247-2 CrossRefPubMedGoogle Scholar
  16. Nishimura A, Tamaoki M, Sato Y, Matsuoka M (1999) The expression of tobacco knotted1-type class 1 homeobox genes corresponds to regions predicted by the cytohistological zonation model. Plant J 18:337–347. doi: 10.1046/j.1365-313X.1999.00457.x CrossRefPubMedGoogle Scholar
  17. Nishimura A, Tamaoki M, Sakamoto T, Matsuoka M (2000) Over-expression of tobacco knotted1-type class1 homeobox genes alters various leaf morphology. Plant Cell Physiol 41:583–590PubMedGoogle Scholar
  18. Sato Y, Tamaoki M, Murakami T, Yamamoto N, Kano-Murakami Y, Matsuoka M (1996a) Abnormal cell divisions in leaf primordial caused by the expression of the rice homeobox gene, OSH1, lead to altered morphology of leaves in transgenic tobacco. Mol Gen Genet 251:13–22PubMedGoogle Scholar
  19. Sato Y, Hong S-K, Tagiri A, Kitano H, Yamamoto N, Nagato Y, Matsuoka M (1996b) A rice homeobox gene, OSH1, is expressed before organ differentiation in a specific region during early embryogenesis. Proc Natl Acad Sci USA 93:8117–8122. doi: 10.1073/pnas.93.15.8117 CrossRefPubMedGoogle Scholar
  20. Sato Y, Sentoku N, Nagato Y, Matsuoka M (1998) Isolation and characterization of a rice homeobox gene, OSH15. Plant Mol Biol 38:983–998. doi: 10.1023/A:1006065622251 CrossRefPubMedGoogle Scholar
  21. Sato Y, Sentoku N, Miura Y, Hirochika H, Kitano H, Matsuoka M (1999) Loss-of-function mutations in the rice homeobox gene OSH15 affect the architecture of internodes resulting in dwarf plants. EMBO J 18:992–1002. doi: 10.1093/emboj/18.4.992 CrossRefPubMedGoogle Scholar
  22. Schneeberger R, Becraft PW, Hake S, Freeling M (1995) Ectopic expression of the knox homeobox gene rough sheath1 alters cell fate in the maize leaf. Genes Dev 9:2292–2304. doi: 10.1101/gad.9.18.2292 CrossRefPubMedGoogle Scholar
  23. Schneeberger R, Tsiantis M, Freeling M, Langdale JA (1998) The rough sheath2 gene negatively regulates homeobox gene expression during maize leaf development. Development 125:2857–2865PubMedGoogle Scholar
  24. Sears ER (1966) Nullisomic–tetrasomic combinations in hexaploid wheat. In: Riley R, Lewis KR (eds) Chromosome manipulation and plant genetics. Oliver and Boyd, Edinburgh, pp 29–45Google Scholar
  25. Sentoku N, Sato Y, Kurata N, Ito Y, Kitano H, Matsuoka M (1999) Regional expression of the rice KN1-type homeobox gene family during embryo, shoot, and flower development. Plant Cell 11:1651–1663CrossRefPubMedGoogle Scholar
  26. Shitsukawa N, Tahira C, Kassai K, Hirabayashi C, Shimizu T, Takumi S, Mochida K, Kawaura K, Ogihara Y, Murai K (2007) Genetic and epigenetic alteration among three homoeologous genes of a class E MADS box gene in hexaploid wheat. Plant Cell 19:1723–1737. doi: 10.1105/tpc.107.051813 CrossRefPubMedGoogle Scholar
  27. Smith HMS, Hake S (2003) The interaction of two homeobox genes, BREVIPEDICELLUS and PENNYWISE, regulates internode patterning in the Arabidopsis inflorescence. Plant Cell 16:1717–1727. doi: 10.1105/tpc.012856 CrossRefGoogle Scholar
  28. Smith LG, Jackson D, Hake S (1995) Expression of knotted1 marks shoot meristem formation during maize embryogenesis. Dev Genet 16:344–348. doi: 10.1002/dvg.1020160407 CrossRefGoogle Scholar
  29. Takumi S, Kosugi T, Murai K, Mori N, Nakamura C (2000) Molecular cloning of three homoeologous cDNAs encoding orthologs of the maize KNOTTED1 homeobox protein from young spikes of hexaploid wheat. Gene 249:171–181. doi: 10.1016/S0378-1119(00)00164-5 CrossRefPubMedGoogle Scholar
  30. Theodoris G, Inada N, Freeling M (2003) Conservation and molecular dissection of ROUGH SHEATH2 and ASYMMETRIC LEAVES1 function in leaf development. Proc Natl Acad Sci USA 100:6837–6842. doi: 10.1073/pnas.1132113100 CrossRefPubMedGoogle Scholar
  31. Timmermans MCP, Hudson A, Becraft PW, Nelson T (1999) ROUGH SHEATH2: a Myb protein that represses knox homeobox genes in maize lateral organ primordia. Science 284:151–153. doi: 10.1126/science.284.5411.151 CrossRefPubMedGoogle Scholar
  32. Tsiantis M, Schneeberger R, Golz JF, Freeliing M, Langdale JA (1999) The maize rough sheath2 gene and leaf development programs in monocot and dicot plants. Science 284:154–156. doi: 10.1126/science.284.5411.154 CrossRefPubMedGoogle Scholar
  33. Venglat SP, Dumonceaux T, Rozwadowski K, Parnell L, Babic V, Keller W, Martienssen R, Selvaraj G, Datla R (2002) The homeobox gene BREVIPEDICELLUS is a key regulator of inflorescence architecture in Arabidopsis. Proc Natl Acad Sci USA 99:4730–4735. doi: 10.1073/pnas.072626099 CrossRefPubMedGoogle Scholar
  34. Vollbrecht E, Reiser L, Hake S (2000) Shoot meristem size is dependent on inbred background and presence of the maize homeobox gene, knotted1. Development 127:3161–3172PubMedGoogle Scholar
  35. Waites R, Hudson A (1995) Phantastica: a gene required for dorsoventrality of leaves in Antirrhinum majus. Development 121:2143–2154Google Scholar
  36. Waites R, Selvadurai HRN, Oliver IR, Hudson A (1998) The Phantastica gene encodes a MYB transcription factor involved in growth and dorsoventrality of lateral organs in Antirrhinum. Cell 93:779–789. doi: 10.1016/S0092-8674(00)81439-7 CrossRefPubMedGoogle Scholar

Copyright information

© Springer Science+Business Media B.V. 2008

Authors and Affiliations

  • Ryoko Morimoto
    • 1
  • Emi Nishioka
    • 1
  • Koji Murai
    • 2
  • Shigeo Takumi
    • 1
  1. 1.Laboratory of Plant Genetics, Graduate School of Agricultural ScienceKobe UniversityKobeJapan
  2. 2.Department of BioscienceFukui Prefectural UniversityFukuiJapan

Personalised recommendations