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Organization and function of shoot apical meristem affecting growth and development in plants

식물의 생장과 발달에 영향을 미치는 슈트 정단분열조직의 체제와 기능

  • Lee, Kyu Bae (Department of Biological Science Education, Chosun University)
  • Received : 2014.11.14
  • Accepted : 2014.12.20
  • Published : 2014.12.31

Abstract

In plants, a shoot apex has a small region known as the shoot apical meristem (SAM) having a group of dividing (initiating) cells. The SAM gives rise to all the groundabove structures of plants throughout their lifetime, and thus it plays important role in growth and development of plants. This review describes theories to explain the SAM organization and function developed over the last 250 years. Since in 1759 German botanist C. F. Wolff has described firstly the SAM, in 1858 Swiss botanist C. N${\ddot{a}}$geli proposed the apical cell theory from the observation of a large single apical cell in the SAM of seedless vascular plants: however, this view was recognized to be unsuitable to seed plants. In 1868, German botanist J. Hanstein suggested the histogen theory: this concept subdividing the SAM into dermatogen, periblem, and plerome was unable to generally apply to seed plants. In 1924, German botanist A. Schmidt proposed the tunica-corpus theory from the examination of angiosperm SAM in which two parts show different planes of cell division: this theory was proved to be not suitable to gymnosperm SAM, not have stable surface tunica layer. In 1938, American botanist A. Foster described zones in gymnosperm SAM based on the cytohistologic differentiation and thus called it a cytohistological zonation theory. With works by E. Gifford, in 1954, this zonation pattern was demonstrated to be also applicable to angiosperm SAM. As another theory, in 1952 French botanist R. Buvat proposed the m${\acute{e}}$rist${\grave{e}}$me d'attente (waiting meristem) theory: however, this concept was confuted because of its negation of function during vegetative growth phase to central initial cells. Rescent studies with Arabidopsis thaliana have found that formation and maintenance of the SAM are under the control of selected genes: SHOOTMERISTEMLESS (STM) gene forms the SAM, and WUSCHEL (WUS) and CLAVATA (CLV) genes function in maintaining the SAM; signaling between WUS and CLV genes act through a negative feedback loop.

식물에서 슈트 정단부에는 분열하는 세포들로 이루어진 슈트 정단분열조직이라는 조그마한 부분이 있다. 슈트 정단분열조직은 그 식물의 일생을 통해서 땅 위의 모든 구조를 만들어 낸다. 이 연구의 목적은 지난 250년 동안 슈트 정단분열조직의 체제와 기능을 설명하기 위해 발전해 온 이론들을 기술하여, 식물의 생장과 발달에 영향을 미치는 슈트 정단분열조직의 중요성을 이해하는 데 있다. 1759년 볼프(C. F. Wolff)가 최초로 슈트 정단분열조직을 기재한 이후, 1858년에 네겔리(C. N${\ddot{a}}$geli)는 무종자 유관속식물의 슈트 정단분열조직에서 하나의 커다란 정단세포를 관찰하여 정단세포설을 제안하였다. 그러나 이 설은 종자식물에 적용할 수 없는 것으로 확인되었다. 이어서 1868년 한스타인(J. Hanstein)에 의해 조직원설이 제한되었으나, 이 설도 종자식물에 일반적으로 적용할 수 없었다. 그 후, 1924년 슈미트(A. Schmidt)은 피자식물의 슈트 정단분열조직에서 세포의 분열면이 서로 다른 것을 관찰하여 초층-내체설을 제안하였다. 이 설은 나자식물에 적용할 수 없는 것으로 확인되었다. 1938년 포스터(A. Foster)는 세포조직학적으로 서로 다른 구역으로 이루어진 나자식물의 슈트 정단부를 관찰하여 세포조직학적 구역화설을 제안하였다. 또한 1954년 기포드(E. Gifford)의 연구에 힘입어 피자식물의 슈트 정단분열조직에도 세포조직학적 구역화설이 적용될 수 있다는 사실이 증명되었다. 또 다른 설로서, 1952년 뷔바(R. Buvat)는 대기 분열조직설이 제안되었으나, 영양생장 시기에 분열조직 중앙의 시원세포들이 분열하지 않는다는 주장이 수용되지 않았다. 최근에 애기장대(Arabidopsis thaliana)를 이용한 연구에서, 슈트 정단분열조직의 형성과 유지가 몇 개의 유전자들에 의해서 조절된다는 사실이 밝혀졌다. 즉, SHOOTMERISTEMLESS(STM) 유전자는 슈트 정단분열조직을 형성하고, WUSCHEL(WUS) 및 CLAVATA (CLV) 유전자들은 슈트 정단분열조직을 유지시키며, WUS와 CLV 두 유전자들 사이의 신호전달은 음성되먹임회로를 통해서 이루어진다.

Keywords

References

  1. Alonso JM, Stepanova AN, Leisse TJ, Kim CJ, Chen H, Shinn P, Stevenson DK, Zimmerman J, Barajas P, Cheuk R, Gadrinab C, Heller C, Jeske A, Koesema E, Meyers CC, Parker H, Prednis L, Ansari Y, Choy N, Deen H, Geralt M, Hazari N, Hom E, Karnes M, Mulholland C, Ndubaku R, Schmidt I, Guzman P, Aguilar-Henonin L, Schmid M, Weigel D, Carter DE, Marchand T, Risseeuw E, Brogden D, Zeko A, Crosby WL, Berry CC, Ecker JR (2003) Genome-Wide Insertional Mutagenesis of Arabidopsis thaliana. Sceince 301:653-656 https://doi.org/10.1126/science.1086391
  2. Anastasiou E, Lenhard M (2007) Growing up to one's standard. Cur Opi Plant Biol 10:63-69 https://doi.org/10.1016/j.pbi.2006.11.002
  3. Barton MK (2010) Twenty years on: The inner workings of the shoot apical meristem, a developmental dynamo. Dev Biol 341:95-113 https://doi.org/10.1016/j.ydbio.2009.11.029
  4. 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 1119:823-831
  5. Beck C (2005) An Introduction to Plant Structure and Development. Cambridge University Press, Cambridge, p 86
  6. Bierhorst DW (1971) Morphology of vascular plants. Macmillian, New York
  7. Bierhorst DW (1977) On the stem apex, leaf initiation and early leaf ontogeny in filicalean fern. Am J Bot 64:125-152 https://doi.org/10.2307/2442101
  8. Bosca S, Knauer S, Laux T (2011) Embryonic development in Arabidopsis thaliana: from the zygote division to the shoot meristem. Front Plant Sci 2:1-6
  9. Bowman J (1994) Arabidopsis, An Atlas of Morphology and Development. Springer Verlag, New York
  10. Bowman JL, Floyd SK (2008) Patterning and polarity in seed plant shoots. Annual Rev Plant Biol 59:67-88 https://doi.org/10.1146/annurev.arplant.57.032905.105356
  11. Brand U, Fletcher JC, Hobe M, Meyerowitz EM, Simon R (2000) Dependence of stem cell fate in Arabidopsis on a feedback loop regulated by CLV3 activity. Science 289:617-619 https://doi.org/10.1126/science.289.5479.617
  12. Brooks L III, Strable J, Zhang X, Ohtsu K, Zhou R, Sarkar A, Hargreaves S, Elshire1 RJ, Eudy D, Pawlowska T, Ware D, Janick-Buckner D, Buckner B, Timmermans MCP, Schnable PS, Nettleton D, Scanlon MJ (2009) Microdissection of shoot meristem functional domains. PLoS Genetics 5(5) e1000476 https://doi.org/10.1371/journal.pgen.1000476
  13. Brown WV, Heimsch C, Emery HP (1957) The organization of the grass shoot apex and systematics. Am J Bot 444:590-595
  14. Brutnell TP, Langdale JA (1998) Signals in leaf development. Adv Bot Res 28:161-195 https://doi.org/10.1016/S0065-2296(08)60296-7
  15. Buvat R (1952) Structure, evolution et fonctionnement du meristeme apical de quelques dicotyledones. Ann Sci Nat Bot Biol 13:199-300
  16. Byrne ME, Barley R, Curtis M, Arroyo JM, Dunham M, Hudson A, Martienssen RA (2000) Asymmetric leaves1mediates leaf patterning and stem cell function in Arabidopsis. Nature 408: 967-971 https://doi.org/10.1038/35050091
  17. Carles CC, Fletcher JC (2003) Shoot apical meristem maintenance: the art of a dynamic balance. Trends Plant Sci 8:394-401 https://doi.org/10.1016/S1360-1385(03)00164-X
  18. Clark SE (2001) Cell signalling at the shoot meristem. Nature Rev Mol Cell Biol 2:276-284 https://doi.org/10.1038/35067079
  19. Clark SE, Running MP, Meyerowitz EM (1995) CLAVATA3 is a specific regulator of shoot and floral meristem development affecting the same processes as CLAVATA1. Development 121:2057-2067
  20. Clowes FAL (1959) Adenin incorporation and cell division in shoot apices. New phytol 58:16-19 https://doi.org/10.1111/j.1469-8137.1959.tb05330.x
  21. Conti L, Bradley D (2007) TERMINAL FLOWER1 is a mobile signal controlling Arabidopsis architecture. Plant Cell 19:767-778 https://doi.org/10.1105/tpc.106.049767
  22. Corson GE Jr, Gifford EM Jr (1969) Histochemical studies of the shoot apex of Datura stramonium during transition to flowering. Phytomorphology 19:189-196
  23. Cutter EG (1959) On the theory of phyllotaxis and histogenesis. Biol Rev 34:243-263
  24. Cutter EG (1980) Plant anatomy: Experimental and interpretation. Part 2 Organs. Edward Arnold. p 56
  25. Davis EL, Rennie P, Steeves TA (1979) Further analytical and experimental studies on the shoot apex of Helianthus annuus: variable activity in the central zone. Can J Bot 57:971-980 https://doi.org/10.1139/b79-119
  26. Dinneny JR, Yadegari R, Fischer RL, Yanofsky MF, Weigel D (2004) The role of JAGGED in shaping lateral organs. Development 131:1101-1110 https://doi.org/10.1242/dev.00949
  27. Dodsworth S (2009) A diverse and intricate signalling network regulates stem cell fate in the shoot apical meristem. Dev Biol 336:1-9 https://doi.org/10.1016/j.ydbio.2009.09.031
  28. Endrizzi K, Moussian B, Haecker A, Levin JZ, Laux T (1996) The SHOOT MERISTEMLESS gene is required for maintenance of undifferentiated cells in Arabidopsis shoot and floral meristems and acts at a different regulatory level than the meristem genes WUSCHEL and ZWILLE. Plant J 10:967-979 https://doi.org/10.1046/j.1365-313X.1996.10060967.x
  29. Esau K (1977) Anatomy of seed plants. 2nd ed. Wiley, New York
  30. Evert RF (2006) Esau's plant anatomy. Meristems, cells, tissues of the plant body-Their structure, function, and development. John Wiley & Sons, Inc, Publication
  31. Fahn A (1990) Plant Anatomy. 4th ed. Butterworth-Heinemann, Oxford, p 61
  32. Fletcher JC, Meyerowitz EM (2000) Cell signalling within the shoot meristem. Curr Opin Plant Biol 3:23-30 https://doi.org/10.1016/S1369-5266(99)00033-3
  33. Fletcher JC, Brand U, Running MP, Simon R, Meyerowitz EM (1999) Signalling of cell fate decisions by CLAVATA3 in Arabidopsis shoot meristems. Science 283:1911-1914 https://doi.org/10.1126/science.283.5409.1911
  34. Foster AS (1938) Structure and growth of the shoot apex in Gingko biloba. B Torrey Bot Club 65:531-556 https://doi.org/10.2307/2480793
  35. Foster AS (1939) Problems of structure, growth and evolution in the shoot apex of seed plants. Bot Rev 5:454-470 https://doi.org/10.1007/BF02878705
  36. Foster AS (1943) Zonal structure and growth of the shoot apex in Microcycas calocoma (Miq.) A. DC. Am J Bot 30:56-73 https://doi.org/10.2307/2437394
  37. Gallois J, Woodward C, Reddy GV, Sablowski R (2002) Combined SHOOT MERISTEMLESS and WUSCHEL trigger ectopic organogenesis in Arabidopsis. Development 129:3207-3217
  38. Gifford EM Jr (1950) The structure and development of the shoot apex in certain woody Ranales. Am J Bot 37:595-611 https://doi.org/10.2307/2437870
  39. Gifford EM Jr (1954) The shoot apex in angiosperms. Bot Rev 20:477-529 https://doi.org/10.1007/BF02957569
  40. Gifford EM Jr, Corson GE Jr (1971) The shoot apex in seed plants. Bot Rev 37:143-229 https://doi.org/10.1007/BF02858956
  41. Gifford EM Jr, Kupila S, Yamaguchi S (1963) Experiments in the application of H3-thymidine and adenine-8-C14 to shoot tips. Phytomorphology 13:14-22
  42. Gifford EM Jr, Polito VS, Nitayangkura S (1979) The epical cell in shoot and roots of certain fern: A reevaluation of its functional role in histogenesis. Plant Sci Lett 15:305-311 https://doi.org/10.1016/0304-4211(79)90135-4
  43. Gross-Hardt R, Laux T (2003) Stem cell regulation in the shoot meristem. J Cell Sci 116:1659-1666 https://doi.org/10.1242/jcs.00406
  44. Haecker A, Laux E (2001) Cell-cell signaling in the shoot meristem. Curr Opin Plant Biol 4:441-446 https://doi.org/10.1016/S1369-5266(00)00198-9
  45. Hall LN, Langdale JA (1996) Molecular genetics of cellular differentiation in leaves. New Phytol 132:533-553 https://doi.org/10.1111/j.1469-8137.1996.tb01873.x
  46. Hanstein J (1868) Die Sheitzellgruppe in Vegetationspunkt der Phanerogamen. In: Festschr Friedrich Wilhelms Universtat Bonn. Niederrhein Ges Natur und Heilkunde, Marcus, Bonn, pp 109-134
  47. Hu YX, Xie O, Chua NH (2003) The Arabidopsis auxininducible gene ARGOS controls lateral organ size. Plant Cell 15:1951-1961 https://doi.org/10.1105/tpc.013557
  48. Irish VF, Sussex IM (1992) A fate map of the Arabidopsis embryonic shoot apical meristem. Development 115:745-753
  49. Johnson MA (1951) The shoot apex in gymnosperms. Phytomorphology 1:188-204
  50. Kayes JM, Clark SE (1998) CLAVATA2, a regulator of meristem and organ development in Arabidopsis. Development 125: 3842-2851
  51. Kessler S, Townsley B, Sinha N (2006) L1 division and differentiation patterns influence shoot apical meristem maintenance. Plant Physiol 141:1349-1362 https://doi.org/10.1104/pp.105.076075
  52. Kurth E (1981) Mitotic activity in the root apex of the water fern Marsilea vestia Hook. And Grev. Am J Bot 68:881-896 https://doi.org/10.2307/2443219
  53. Kwiatkowska D (2008) Flowering and apical meristem growth dynamics. J Exp Bot 59:187-201 https://doi.org/10.1093/jxb/erm290
  54. Lamesch P, Berardini TZ, Li D, Swarbreck D, Wilks C, Sasidharan R, Muller R, Dreher K, Alexander DL, Garcia-Hernandez M, Karthikeyan AS, Lee CH, Nelson WN, Ploetz L, Singh S, Wensel A, Eva Huala (2011) The Arabidopsis Information Resource (TAIR): improved gene annotation and new tools. Nucleic Acids Res 40:D1202-D1210
  55. Laufs P, Grandjean O, Jonak C, Kieu K, Traas J (1998) Cellular parameters of the shoot apical meristem in Arabidopsis. Plant Cell 10:1375-1389 https://doi.org/10.1105/tpc.10.8.1375
  56. Laux T, Mayer KFX, Berger J, Jurgens G (1996) The WUSCHEL gene is required for shoot and floral meristem integrity in Arabidopsis. Development 122:87-96
  57. Lee KB (2012) Plant Morphology. 2nd ed, Life Science Publishing Co. Seoul, pp 49-51
  58. Lenhard M, Laux T (1999) Shoot meristem formation and maintenance. Curr Opin Plant Biol 2:44-50 https://doi.org/10.1016/S1369-5266(99)80009-0
  59. Lenhard M, Bohnert A, Jurgens G, Laux T (2001) Termination of stem cell maintenance in Arabidopsis floral meristems by interactions between WUSCHEL and AGAMOUS. Cell 105: 805-814 https://doi.org/10.1016/S0092-8674(01)00390-7
  60. Lenhard M, Jurgens G, Laux T (2002) The WUSCHEL and SHOOTMERISTEMLESS genes fulfil complementary roles in Arabidopsis shoot meristem regulation. Development 129:3195-3206
  61. Leyser O, Day S (2003) Mechanism in plant development. Blackwell Publishing
  62. Li Y, Zheng L, Corke F, Smith C, Bevan MW (2008) Control of final seed and organ size by the DA1 gene family in Arabidopsis thaliana. Genes Dev 22:1331-1336 https://doi.org/10.1101/gad.463608
  63. Lohmann JU, Hong RL, Hobe M, Busch MA, Parcy F, Simon R, Weigel D (2001) A molecular link between stem cell regulation and floral patterning in Arabidopsis. Cell 105:793-803 https://doi.org/10.1016/S0092-8674(01)00384-1
  64. Long JA, Barton MK (1998) The development of apical embryonic pattern in Arabidopsis. Development 125:3027-3055
  65. Long JA, Barton MK (2000) Initiation of axillary and floral meristems in Arabidopsis. Dev Biol 218:341-353 https://doi.org/10.1006/dbio.1999.9572
  66. 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 379:66-69 https://doi.org/10.1038/379066a0
  67. Lyndon RF (1970) Rate of cell division in the shoot apical meristem of Pisum. Ann Bot (London) 34:1-17 https://doi.org/10.1093/oxfordjournals.aob.a084343
  68. Lyndon RF (1976) The shoot apex. In: Yeoman MM (ed), Cell Division in Higher Plants. Academic Press, New York. pp 285-314
  69. Lyndon RF (1998) The shoot apical meristem, its growth and development. Cambridge University Press. Cambridge.
  70. Lynn K, Fernandez A, Aida M, Sedbrook J, Tasaka M, Masson P, Barton MK (1999) The PINHEAD/ZWILLE gene acts pleiotropically in Arabidopsis development and has overlapping functions with the ARGONAUTE1 gene. Development 126: 469-481
  71. Mauseth JD (1978) An investigation of the morphogenetic mechanisms which control the development of zonation in seedling shoot apical meristems. Am J Bot 65:158-167 https://doi.org/10.2307/2442449
  72. Mauseth JD (1988) Plant Anatomy. The Benjamin/Cummings Publishing Co., Inc., Menlo Park, California, p 88
  73. Mayer KFX, Schoof H, Haecker A, Lenhard M, Jurgens G, Laux T (1998) Role of WUSCHEL in regulating stem cell fate in the Arabidopsis shoot meristem. Cell 95:805-815 https://doi.org/10.1016/S0092-8674(00)81703-1
  74. Medford JI (1992) Vegetative apical meristems. Plant Cell 4: 1029-1039 https://doi.org/10.1105/tpc.4.9.1029
  75. Medford JI, Behringer FJ, Callos JD, Feldmann KA (1992) Normal and abnormal development in the Arabidopsis vegetative shoot apex. Plant Cell 4:631-643 https://doi.org/10.1105/tpc.4.6.631
  76. Meinke DW, Cherry JM, Dean C, Rounsley SD, Koornneef M (1998) Arabidopsis thaliana: A Model Plant for Genome Analysis. Science 282:62-682
  77. Meyerowitz EM (1997) Genetic control of cell division patterns in developing plants. Cell 88:299-308 https://doi.org/10.1016/S0092-8674(00)81868-1
  78. Meyerowitz EM (2001) Prehistory and History of Arabidopsis Research. Plant Physiol 125:15-19 https://doi.org/10.1104/pp.125.1.15
  79. Miwa H, Kinoshita A, Fukuda H, Sawa S (2009) Plant meristems: CLAVATA3/ ESR-related signalling in the shoot apical meristem and the root apical meristem. J Plant Res 122:31-39 https://doi.org/10.1007/s10265-008-0207-3
  80. Moore R, Clark WD, Vodopich D (1998) Botany. 2nd ed. WBC McGraw-Hill
  81. Murray AH, Jones A, Godin C, Traas J (2012) Systems analysis of shoot apical meristem growth and development: Integrating hormonal and mechanical signaling. Plant Cell 24:3907-3919 https://doi.org/10.1105/tpc.112.102194
  82. Nageli C (1858) Das Wachsthum des Stammes und der Wurzel bei den Gefasspflanzen und die Anordnung der Gefasstrange in Stengel. Beitr Wissenschaft Bot 1:1-156
  83. Nilsson O, Lee I, Blazquez MA, Weigel D (1998) Flowering-time genes modulate the response to LEAFY activity. Genetics 150:403-410
  84. Page DR, Grossniklaus U (2002) The art and design of genetic screens : Arabidopsis thaliana. Nat Rev Genet 3:124-136 https://doi.org/10.1038/nrg730
  85. Pilkington M (1929) The regeneration of the stem apex. New Phytol 28:37-53 https://doi.org/10.1111/j.1469-8137.1929.tb06746.x
  86. Poethig RS, Sussex IM (1985) The developmental morphology and growth dynamics of the tobacco leaf. Planta 165:158-169 https://doi.org/10.1007/BF00395038
  87. Popham RA, Chan AP (1950) Zonation in the vegetavive stem tip of Chrysanthemum morifolium Bailey. Am J Bot 37:476-484 https://doi.org/10.2307/2438220
  88. Reddy GV (2008) Live-imaging stem-cell homeostasis in the Arabidopsis shoot apex. Curr Opin Plant Biol 11:88-93 https://doi.org/10.1016/j.pbi.2007.10.012
  89. Reddy GV, Meyerowitz EM (2005) Stem-cell homeostasis and growth dynamics can be uncoupled in the Arabidopsis shoot apex. Science 310:663-667 https://doi.org/10.1126/science.1116261
  90. Reddy GV, Heisler MG, Ehrhardt DW, Meyerowitz EM (2004) Real-time lineage analysis reveals oriented cell divisions associated with morphogenesis at the shoot apex of Arabidopsis thaliana. Development 131:4225-4237 https://doi.org/10.1242/dev.01261
  91. Reinhardt D, Frenz M, Mandel T, Kuhlemeier C (2003) Microsurgical and laser ablation analysis of interactions between the zones and layers of the tomato shoot apical meristem. Development 130:4073-4083 https://doi.org/10.1242/dev.00596
  92. Saint-Come R (1966) Applications des techniques histoautogadiographiques et des methods a l'etude du functionnement apical chez le Coleus blumei Beneth. Rev Gen Bot 73:241-324
  93. Sekhar KNC, Sawhney VK (1985) Ultrastructure of the shoot apex of tomato (Solanum lycopersicum). Am J Bot 72:1813-1822 https://doi.org/10.2307/2443738
  94. Schmidt A (1924) Histologische Studien an Phanerogamen Vegetationspunkten. Botanik Archiv 8:345-404
  95. Schoof H, Lenhard M, Haecker A, Mayer KFX, Jurgens G, Laux T (2000) The stem cell population of Arabidopsis shoot meristems is maintained by a regulatory loop between the CLAVATA and WUSCHEL genes. Cell 100:635-644 https://doi.org/10.1016/S0092-8674(00)80700-X
  96. Scofield S, Murray JAH (2006) KNOX gene function in plant stem cell niches. Plant Mol Biol 60:929-946 https://doi.org/10.1007/s11103-005-4478-y
  97. Sinha N (1999) Leaf development in angiosperms. Annu Rev Plant Physiol Plant Mol Biol 50:419-446 https://doi.org/10.1146/annurev.arplant.50.1.419
  98. Smith LG, Greene B, Veit, Hake S (1992) A dominant mutation in the maize homeobox gene, Knotted-1, causes itsectopic expression in leaf cells with altered fates. Development 116:21-30
  99. Snow M, Snow R (1951) Minimum areas and leaf determination. Philos Trans R Soc Lond Ser B 139:545-566
  100. Steeves TA (2006) The shoot apical meristem: an historical perspective. Can J Bot 84: 1629-1633 https://doi.org/10.1139/b06-144
  101. Steeves TA, Sussex IM (1989) Patterns in plant development. 2nd ed. Cambridge University Press, Cambridge, UK
  102. Stewart RN, Dermen H (1970) Determination of number and mitotic activity of shoot apical initial cells by analysis of mericlinal chimeras. Am J Bot 57:816-826 https://doi.org/10.2307/2441339
  103. Sussex IM (1952) Regeneration of the potato shoot apex. Nature 170:755-757
  104. Sussex IM (1964) The permanence of meristems: Developmental organizers or reactors to exogenous stimuli? Brookhaven Symp Biol 16:1-12
  105. Takacs EM, Li J, Du C, Ponnala L, Janick-Buckner D, Yu J, Muehlbauer GJ, Schnable PS, Timmermans MCP, Sun Q, Nettleton D, Scanlon MJ (2010) Ontogeny of the maize shoot apical meristem. Plant Cell 24:3219-3234
  106. The Arabidopsis Genome Initiative (2001) Analysis of the genome sequence of the flowering plant Arabidopsis thaliana. Nature 408:796-815
  107. Tooke F, Battey N (2003) Models of shoot apical meristem function. New Phytol 159:37-52 https://doi.org/10.1046/j.1469-8137.2003.00803.x
  108. Turck F, Fornara F, Coupland G, 2008. Regulation and identity of florigen, FLOWERING LOCUS T moves center stage. Annu Rev Plant Biol 59:573-594 https://doi.org/10.1146/annurev.arplant.59.032607.092755
  109. van Lijsebettens M, Clarke J (1998) Leaf development in Arabidopsis. Plant Physiol Biochem 36:47-60 https://doi.org/10.1016/S0981-9428(98)80090-9
  110. Vaughn JG (1952) Structure of the angiosperm apex. Nature 169:458-459 https://doi.org/10.1038/169458a0
  111. Vaughn JG (1955) The morphology and growth of the vegetative and reproductive apices of Arabidopsis thaliana (L) Heynh, Capsella bursapastoris (L) Medic and Anagellis arrensis. J Linn Soc Bot 55:279-30 x 240 https://doi.org/10.1111/j.1095-8339.1955.tb00014.x
  112. Vernoux T, Autran D, Trass J (2000) Developmental control of cell divison patterns in the shoot apex. Plant Mol Biol 43:569-581 https://doi.org/10.1023/A:1006464430936
  113. Vernoux T, Besnard F, Trass J (2010) Auxin at the shoot apical meristem. Cold Spring Harb Symp Quant Biol 2 a001487
  114. Wardlaw CW (1957) On the organization and reactivity of the shoot apex in vascular plants. Am J Bot 44:176-185 https://doi.org/10.2307/2438308
  115. Weigel D, Jurgens G (2002) Stem cells that make stems. Nature 415:751-754 https://doi.org/10.1038/415751a
  116. Williams L, Fletcher JC (2005) Stem cell regulation in the Arabidopsis shoot apical meristem. Curr Opin Plant Biol 8:582-586 https://doi.org/10.1016/j.pbi.2005.09.010
  117. Wolff CF (1759) Theoria Generationis. Verlag von Wielhelm Engelman, Leipzig, Germany
  118. Yadav RK, Girke T, Pasala S, Xie M, Reddy GV (2009) Gene expression map of the Arabidopsis shoot apical meristem stem cell niche. Proc Nat Acad Sci 106:494