The collet (root-hypocotyl junction) region is an important plant transition zone between soil and atmospheric environments. Despite its crucial importance for plant development, little is known about how this transition zone is specified. Here we document the involvement of the exocyst complex in this process. The exocyst, an octameric tethering complex, participates in secretion and membrane recycling and is central to numerous cellular and developmental processes, such as growth of root hairs, cell expansion, recycling of PIN auxin efflux carriers and many others. We show that dark-grown Arabidopsis mutants deficient in exocyst subunits can form a hair-bearing ectopic collet-like structure above the true collet, morphologically resembling the true collet but also retaining some characteristics of the hypocotyl. The penetrance of this phenotypic defect is significantly influenced by cultivation temperature and carbon source, and is related to a defect in auxin regulation. These observations provide new insights into the regulation of collet region formation and developmental plasticity of the hypocotyl.

Department of Experimental Plant Biology Faculty of Science Charles University Prague 2 Czech Republic

Institute of Animal Physiology and Genetics Academy of Sciences of the Czech Republic Liběchov Czech Republic

Institute of Experimental Botany Academy of Sciences of the Czech Republic Prague 6 Czech Republic

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Alonso JM, Stepanova AN, Leisse TJ, et al. . 2003. Genome-wide insertional mutagenesis of Arabidopsis thaliana. Science 301, 653–657. PubMed

Bates D, Mächler M, Bolker B, Walker S. 2014. Fitting linear mixed-effects models using lme4. arXiv, 1406.5823. [Preprint].

Boerjan W, Cervera MT, Delarue M, Beeckman T, Dewitte W, Bellini C, Caboche M, Van Onckelen H, Van Montagu M, Inzé D. 1995. Superroot, a recessive mutation in Arabidopsis, confers auxin overproduction. The Plant Cell 7, 1405–1419. PubMed PMC

Cole RA, Synek L, Žarský V, Fowler JE. 2005. SEC8, a subunit of the putative Arabidopsis exocyst complex, facilitates pollen germination and competitive pollen tube growth. Plant Physiology 138, 34–45. PubMed PMC

Correa LdaR, Troleis J, Mastroberti AA, Mariath JE, Fett-Neto AG. 2012. Distinct modes of adventitious rooting in Arabidopsis thaliana. Plant Biology 14, 100–109. PubMed

Cvrčková F, Grunt M, Bezvoda R, Hála M, Kulich I, Rawat A, Zárský V. 2012. Evolution of the land plant exocyst complexes. Frontiers in Plant Science 3, 159. PubMed PMC

Drdová EJ, Synek L, Pečenková T, Hála M, Kulich I, Fowler JE, Murphy AS, Zárský V. 2013. The exocyst complex contributes to PIN auxin efflux carrier recycling and polar auxin transport in Arabidopsis. The Plant Journal 73, 709–719. PubMed

Fendrych M, Synek L, Pečenková T, et al. . 2010. The Arabidopsis exocyst complex is involved in cytokinesis and cell plate maturation. The Plant Cell Online 22, 3053. PubMed PMC

Fendrych M, Synek L, Pečenková T, Drdová EJ, Sekeres J, de Rycke R, Nowack MK, Zársky V. 2013. Visualization of the exocyst complex dynamics at the plasma membrane of Arabidopsis thaliana. Molecular Biology of the Cell 24, 510–520. PubMed PMC

Hála M, Cole R, Synek L, et al. . 2008. An exocyst complex functions in plant cell growth in Arabidopsis and tobacco. The Plant Cell 20, 1330–1345. PubMed PMC

Hu W, Ma H. 2006. Characterization of a novel putative zinc finger gene MIF1: involvement in multiple hormonal regulation of Arabidopsis development. The Plant Journal 45, 399–422. PubMed

Ito T, Motohashi R, Shinozaki K. 2002. Preparation of transposon insertion lines and determination of insertion sites in Arabidopsis genome. Methods in Molecular Biology 182, 209–219. PubMed

Jensen PJ, Hangarter RP, Estelle M. 1998. Auxin transport is required for hypocotyl elongation in light-grown but not dark-grown Arabidopsis. Plant Physiology 116, 455–462. PubMed PMC

King JJ, Stimart DP, Fisher RH, Bleecker AB. 1995. A mutation altering auxin homeostasis and plant morphology in Arabidopsis. The Plant Cell 7, 2023–2037. PubMed PMC

Koumandou VL, Dacks JB, Coulson RM, Field MC. 2007. Control systems for membrane fusion in the ancestral eukaryote; evolution of tethering complexes and SM proteins. BMC Evolutionary Biology 7, 29. PubMed PMC

Kulich I, Cole R, Drdová E, Cvrcková F, Soukup A, Fowler J, Zárský V. 2010. Arabidopsis exocyst subunits SEC8 and EXO70A1 and exocyst interactor ROH1 are involved in the localized deposition of seed coat pectin. New Phytologist 188, 615–625. PubMed

Kulich I, Vojtíková Z, Glanc M, Ortmannová J, Rasmann S, Žárský V. 2015. Cell wall maturation of Arabidopsis trichomes is dependent on exocyst subunit EXO70H4 and involves callose deposition. Plant Physiology 168, 120–131. PubMed PMC

Lehman A, Black R, Ecker JR. 1996. HOOKLESS1, an ethylene response gene, is required for differential cell elongation in the Arabidopsis hypocotyl. Cell 85, 183–194. PubMed

Lilley JL, Gee CW, Sairanen I, Ljung K, Nemhauser JL. 2012. An endogenous carbon-sensing pathway triggers increased auxin flux and hypocotyl elongation. Plant Physiology 160, 2261–2270. PubMed PMC

Lin Y, Schiefelbein J. 2001. Embryonic control of epidermal cell patterning in the root and hypocotyl of Arabidopsis. Development 128, 3697–3705. PubMed

Ohashi Y, Oka A, Rodrigues-Pousada R, Possenti M, Ruberti I, Morelli G, Aoyama T. 2003. Modulation of phospholipid signaling by GLABRA2 in root-hair pattern formation. Science 300, 1427–1430. PubMed

Poupart J, Rashotte AM, Muday GK, Waddell CS. 2005. The rib1 mutant of Arabidopsis has alterations in indole-3-butyric acid transport, hypocotyl elongation, and root architecture. Plant Physiology 139, 1460–1471. PubMed PMC

Qing L, Aoyama T. 2012. Pathways for epidermal cell differentiation via the homeobox gene GLABRA2: update on the roles of the classic RegulatorF. Journal of Integrative Plant Biology 54, 729–737. PubMed

Rawat A, Brejšková L, Hála M, Cvrčková F, Žárský V. 2017. The Physcomitrella patens exocyst subunit EXO70.3d has distinct roles in growth and development, and is essential for completion of the moss life cycle. New Phytologist 216, 438–454. PubMed

Rolland F, Baena-Gonzalez E, Sheen J. 2006. Sugar sensing and signaling in plants: conserved and novel mechanisms. Annual Review of Plant Biology 57, 675–709. PubMed

Scheres B, McKhann HI, Van Den Berg C. 1996. Roots redefined: anatomical and genetic analysis of root development. Plant Physiology 111, 959–964. PubMed PMC

Scheres B, Wolkenfelt H, Willemsen V, Terlouw M, Lawson E, Dean C, Weisbeek P. 1994. Embryonic origin of the Arabidopsis primary root and root meristem initials. Development 120, 2475–2487.

Sliwinska E, Mathur J, Bewley JD. 2012. Synchronously developing collet hairs in Arabidopsis thaliana provide an easily accessible system for studying nuclear movement and endoreduplication. Journal of Experimental Botany 63, 4165–4178. PubMed

Sliwinska E, Mathur J, Bewley JD. 2015. On the relationship between endoreduplication and collet hair initiation and tip growth, as determined using six Arabidopsis thaliana root-hair mutants. Journal of Experimental Botany 66, 3285–3295. PubMed

Stokes ME, Chattopadhyay A, Wilkins O, Nambara E, Campbell MM. 2013. Interplay between sucrose and folate modulates auxin signaling in Arabidopsis. Plant Physiology 162, 1552–1565. PubMed PMC

Synek L, Schlager N, Eliáš M, Quentin M, Hauser MT, Žárskỳ V. 2006. AtEXO70A1, a member of a family of putative exocyst subunits specifically expanded in land plants, is important for polar growth and plant development. The Plant Journal 48, 54–72. PubMed PMC

Tanaka T, Tanaka H, Machida C, Watanabe M, Machida Y. 2004. A new method for rapid visualization of defects in leaf cuticle reveals five intrinsic patterns of surface defects in Arabidopsis. The Plant Journal 37, 139–146. PubMed

Truernit E, Bauby H, Dubreucq B, Grandjean O, Runions J, Barthélémy J, Palauqui JC. 2008. High-resolution whole-mount imaging of three-dimensional tissue organization and gene expression enables the study of phloem development and structure in Arabidopsis. The Plant Cell 20, 1494–1503. PubMed PMC

Ulmasov T, Murfett J, Hagen G, Guilfoyle TJ. 1997. Aux/IAA proteins repress expression of reporter genes containing natural and highly active synthetic auxin response elements. The Plant cell 9, 1963–1971. PubMed PMC

Verstraeten I, Schotte S, Geelen D. 2014. Hypocotyl adventitious root organogenesis differs from lateral root development. Frontiers in Plant Science 5, 495. PubMed PMC

Wen TJ, Hochholdinger F, Sauer M, Bruce W, Schnable PS. 2005. The roothairless1 gene of maize encodes a homolog of sec3, which is involved in polar exocytosis. Plant Physiology 138, 1637–1643. PubMed PMC

Wu B, Guo W. 2015. The exocyst at a glance. Journal of Cell Science 128, 2957–2964. PubMed PMC

Žádníková P, Petrášek J, Marhavý P, et al. . 2010. Role of PIN-mediated auxin efflux in apical hook development of Arabidopsis thaliana. Development 137, 607–617. PubMed

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