Visn. Hark. nac. agrar. univ., Ser. Biol., 2020, Issue 3 (51), p. 98-123



V. Y. Dzhamieiev

Kharkiv National Medical University

(Kharkiv, Ukraine)


Auxin (indolyl-3-acetic acid, IAA) is one of the key classical phytohormones with a very wide range of physiological effects. The first part of the scientific lecture describes the main stages of discovery of the hormone. The main pathways of auxin synthesis in plant tissues, which is carried out in two different ways: tryptophan-dependent and tryptophan-independent, are considered in detail. At the same time, multiple pathways of the auxin formation from tryptophan have been found in plant tissues. Among them, the mechanisms that occur with the formation of such intermediate metabolites as indole-3-acetaldoxime, indole-3-pyruvate and indole-3-acetamide are considered. The indole-3-pyruvate pathway is currently considered the main mechanism of hormone synthesis. Experimental evidence has also been obtained for the functioning of the tryptophan-independent pathway of auxin synthesis, the key enzyme of which is cytoplasmic indole synthase. It is assumed that the precursor of auxin in the tryptophan-independent pathway may be some intermediate metabolite between anthranilic acid and tryptophan. The article also describes the routes of auxin inactivation through the formation of conjugated forms and oxidation. A brief characterization of IAA dioxygenases, belonging to the 2-oxoglutarate-Fe (II)-oxygenases family, which are currently considered the main catalytic systems for auxin oxidation, is presented. The mechanisms and significance of polar and lateral transport of auxin are discussed. The characteristics of transmembrane auxin transporters belonging to the families PIN/PIL, ABCB/PGP and AUX/LAX are given.

Key words: auxin, auxin synthesis, indolyl-3-butyric acid, conjugates, auxin transport, PIN, PIL, ABCB/PGP, AUX/LAX



1. Bokut' S.B., Gerasimovich N.V., Milyutin A.A. 2005. Molekulyarnaya biologiya: molekulyarnyye mek-hanizmy khraneniya, vosproizvedeniya i realizatsii geneticheskoy informatsii (Molecular Biology: Mo-lecular Mechanisms Of Storage, Reproduction And Implementation Of Genetic Information) (eds. Mel'nik L.S., Kas'yanovoy L.D.) Minsk : 463 p. (In Russian)
2. Kovrizhnykh V.V., Omelyanchuk N.A., Pasternak T.P., Mironova V.V. 2014. The key role of PIN proteins in the transport of auxin in the root of Arabidopsis thaliana L. Vavilovskiy zhurnal genetiki i selektsii. 18 (4/1) : 797-806. (In Russian).
3. Pozhvanov G.A., Suslov D.V., Medvedev S.S. 2013. Rearrangements of the actin cytoskeleton during the gravitropic reaction of the roots of Arabidopsis. Tsitologiya. 55 (1) : 28-35. (In Russian).
4. Polevoy V.V. 1982. Fitogormony (Phytohormones). Leningrad : 249 p. (In Russian).
5. Kholodniy M.G. 1927. Growth hormones and tropisms in plants. Zap. Kyyiv. in-tu nar. osvity. 2 : 69-88. (In Ukrainian).
6. Adamowski M., Friml J. 2015. PIN-Dependent Auxin Transport: Action, Regulation, and Evolution. The Plant Cell. 27 : 20-32.
7. Bajguz A, Piotrowska A. 2009. Conjugates of auxin and cytokinin. Phytochemistry 70 : 957-969.
8. Baldi B.G., Maher B.R., Slovin J.P., Cohen J.D. 1991. Stable isotope labeling, in vivo, of D- and L-tryptophan pools in Lemna gibba and the low incorporation of label into indole-3-acetic acid. Plant Physiol. 95 : 1203-1208.
9. Bandurski R.S., Cohen J.D., Slovin J.P., Reinecke D.M. 1995. Auxin biosynthesis and metabolism. See Ref. 17a: 39-65.
10. Barbez E., Kubes M., Rolccik J., Beziat C., Pencik A., Wang B., Rosquete M. R., Zhu J., Dobrev P. I., Lee Y., Zazimalova E., Petrasek J., Geisler M., Friml J., Kleine-Vehn J. 2012. A novel putative auxin carrier family regulates intracellular auxin home-ostasis in plants. Nature. 485 : 119-122.
11. Bartel B. 1997. Auxin biosynthesis. Ann. Rev. Plant Physiol. Plant Mo. Biol. 48 : 51-66.
12. Bennett M.J., Marchant A., Green H.G., May S.T., Ward S.P., Millner P.A., Walker A. R., Schulz B., Feldmann K. A. 1996. Arabidopsis AUX1 gene: a permease-like regulator of root gravitropism. Science. 273 : 948-950.
13. Bennett T., Brockington S. F., Rothfels C., Gra-ham S.W., Stevenson D., Kutchan T., Rolf M., Thomas P., Wong G. K., Leyser O., Glover B.J., Harrison C.J. 2014. Paralogous radiations of PIN proteins with multiple origins of noncanonical PIN structure. Mol. Biol. Evol. 31 : 2042-2060.
14. Blakeslee J.J., Bandyopadhyay A., Lee O.R., Mravec J., Titapiwatanakun B., Sauer M., Makam S. N., Cheng Y., Bouchard R., Adamec J., Geisler M., Na-gashima A., Sakai T., Martinoia E., Friml J, Peer W.A., Murphy A.S. 2007. Interactions among PIN-FORMED and P-glycoprotein auxin transporters in Arabidopsis. Plant Cell. 19 : 131-147.
15. Blakeslee J.J., Peer W.A., Murphy A.S. 2005. Auxin transport. Curr. Opin. Plant Biol. 8 : 494-500.
16. Blilou I., Xu J., Wildwater M., Willemsen V., Paponov I., Friml J., Heidstra R., Aida M, Palme K., Scheres B. 2005. The PIN auxin efflux facilitator network controls growth and patterning in Arabidopsis roots. Nature. 433 : 39-44.
17. Blommaert, K. L. J. 1954. Growth and inhibiting sub-stances in relation to the rest period of the potato tuber. Nature. 174 : 970-972.
18. Butler E.D. 2000. Characterization of auxin-induced ARRO-1 expression in the primary root of Malus domestica. J. Exp. Bot. 51 : 1765-1766.
19. Cambridge A.P., Morris D.A. 1996. Transfer of exogenous auxin from the phloem to the polar auxin transport pathway in pea (Pisum sativum L.). Planta. 199 : 583-588.
20. Campanella J.J., Larko D., Smalley J. 2003. A molecular phylogenomic analysis of the ILR1-like family of IAA amidohydrolase genes. Comparative and Functional Genomics. 4 : 584-600.
21. Ciesielski T. 1872. Untersuchungen über die Ab-wärtskrümmung der Wurzel. Beitraege zur Biologie der Pflanzen. 1 : 1-30.
22. Chen Q., Dai X., De-Paoli H., Cheng Y., Takebayashi Y., Kasahara H., Kamiya Y., Zhao Y. 2014. Auxin overproduction in shoots cannot rescue auxin deficiencies in Arabidopsis roots. Plant Cell Physiol. 55 : 1072-1079.
23. Cheng Y, Dai X, Zhao Y. 2006. Auxin biosynthesis by the YUCCA flavin monooxygenases controls the formation of floral organs and vascular tissues in Arabidopsis. Genes Dev. 20 : 1790-1799.
24. Cholodny N. 1926. Beiträge zur Analyse der geotropi-schen Reaktion. Jahrb. wiss. Bot. 65 : 447-459.
25. Darwin C. R. 1880. The power of movement in plants. London : John Murray. 592 p.
26. Derffling K. 1982. Das Hormonsуstem der Pflanzen. Stuttgart, New York.
27. Dhonukshe P., Huang F., Galvan-Ampudia C. S., Mähönen A: , Kleine-Vehn J., Xu J., Quint A., Prasad K., Friml J., Scheres B., Offringa R. 2010. Plasma membrane-bound AGC3 kinases phosphorylate PIN auxin carriers at TPRXS(N/S) motifs to direct apical PIN recycling. Development. 137 : 3245-3255.
28. Ding Z.,Wang B., Moreno I., Dupláková N., Simon S., Carraro N., Reemmer J., Pencik A., Chen X., Tejos R., Skupa P., Pollmann S., Mravec J., Petrasek J., Zazimalova E., Honys D., Rolcik J., Murphy A., Orellana A., Geisler M., Friml J. 2012. ER-localized auxin transporter PIN8 regulates auxin homeostasis and male gametophyte development in Arabidopsis. Nat. Commun. 3, 941. doi:10.1038.
29. Enders T.A., Strader L.C. 2015. Auxin activity: past, present, and future. Amer. J. Bot. 102 (2) : 180-196.
30. Epstein E., Cohen J.D., Bandurski R.S. 1980. Concentration and metabolic turnover of indoles in germinating kernels of Zea mays L. Plant Physiol. 65: 415-421.
31. Farrow S.C., Facchini P.J. 2014. Functional diversity of 2-oxoglutarate/Fe(II)-dependent dioxygenases in plant metabolism. Front. Plant Sci. 5, 524.
32. Feraru E., Feraru M.I., Kleine-Vehn J., Martiniere A., Mouille G., Vanneste S., Vernhettes S., Runions J., Friml J. 2011. PIN polarity maintenance by the cell wall in Arabidopsis. Curr. Biol. 21 : 338-343.
33. Friml J., Benková E., Blilou I., Wiśniewska J., Hamann T., Ljung K., Woody S., Sandberg G., Scheres B., Jürgens G., Palme K. 2002. AtPIN4 Mediates sink-driven auxin gradients and root patterning in Arabidopsis. Cell. 108 : 661-673.
34. Friml J., Palme K. 2002. Polar auxin transport - old questions and new concepts? Plant Molecular Biolo-gy. 49: 273-284.
35. Friml J., Vieten A., Sauer M., Weijers D., Schwarz H., Hamann T., Offringa R., Jürgens G. 2003. Efflux-dependent auxin gradients establish the apical-basal axis of Arabidopsis. Nature. 426 : 147-153.
36. Friml J., Wiśniewska J., Benková E., Mendgen K., Palme K. 2002. Lateral relocation of auxin efflux regulator PIN3 mediates tropism in Arabidopsis. Nature. 415 : 806-809.
37. Gälweiler L., Guan C., Müller A., Wisman E., Mendgen K., Yephremov A., Palme K. 1998. Regulation of polar auxin transport by AtPIN1 in Arabidopsis vascular tissue. Science. 282 : 2226-2230.
38. Ganguly A., Park M., Kesawat M. S., Cho H.-T. 2014. Functional analysis of the hydrophilic loop in intra-cellular trafficking of Arabidopsis PIN-FORMED proteins. Plant Cell. 26 : 1570-1585.
39. Geisler M., Murphy A.S. 2006. The ABC of auxin transport: the role of P-glycoproteins in plant devel-opment. FEBS Lett. 580 : 1094-1102.
40. Geldner N., Anders N., Wolters H., Keicher J., Kornberger W., Muller P., Delbarre A., Ueda T., Nakano A., Jürgens G. 2003. The Arabidopsis GNOM ARF-GEF mediates endosomal recycling, auxin transport, and auxin-dependent plant growth. Cell. 112 : 219-230.
41. Goldsmith M.H.M. 1977. The polar transport of auxin. Annu. Rev. Plant Physiol. 28 : 439-478.
42. Goodwin T.W., Mercer E.I. 1983. Introduction to Plant Biochemistry. Vol. 2. Oxford, New York, Toronto, Sydney, Paris, Frankfurt.
43. Grones P., Chen X., Simon S., Kaufmann W.A., De Rycke R., Nodzyński T., ZazimalovaE., Friml J. 2015. Auxin-binding pocket of ABP1 is crucial for its gain-of-function cellular and developmental roles. J. Exp. Bot. 66, 16 : 5055-5065.
44. Herrmann K. M. 1995. The Shikimate pathway: Early steps in the biosynthesis of aromatic compounds. The Plant Cell. 7 : 907-919.
45. Heslop-Harrison J. 1979. Darwin and the movement of plants: A retrospect. In: Plant Growth Substances (ed. Skoog F.). Springer-Verlag, Berlin, Heidelber, New York, pp. 3-14.
46. Jackson R.G., Lim E.-K., Li Y., Kowalczyk M., Sand-berg G., Hoggett J., Ashford D.A., Bowles D.J. 2001. Identification and biochemical characterization of an Arabidopsis indole-3-acetic acid glucosyltransferase. Journal of Biological Chemistry. 276 : 4350-4356.
47. Jain M., Kaur N., Tyagi A.K., Khurana J.P. 2006. The auxin-responsive GH3 gene family in rice (Oryza sa-tiva). Functional and Integrative Genomics. 6 : 36-46.
48. Jensen P. B. 1936. Über die Verteilung des Wuchsstoffes in Keimstengeln und Wurzeln während der pho-totropischen und geotropischen Krümmung. Danske videnskabernes selskab. Biologiske meddelelser. 13 (1) : 3-31.
49. Kasahara H. 2015. Current aspects of auxin biosynthesis in plants. Biosci. Biotechnol. Biochem. 80 : 34-42.
50. Kleine-Vehn J., Dhonukshe P., Swarup R., Bennett M., Friml J. 2006. Subcellular trafficking of the ara-bidopsis auxin influx carrier AUX1 Uses a novel pathway distinct from PIN1 The Plant Cell. 18 : 3171-3181.
51. Kleine-Vehn, J., Wabnik K, Martinière A., Łangowski Ł., Willig K., Naramoto S., Leitner J, Tanaka H., Jakobs S., Robert S., Luschnig C., Govaerts W., Hell S. W., Runions J., Friml J. 2011. Recycling, clustering, and endocytosis jointly maintain PIN auxin carrier polarity at the plasma membrane. Mol. Syst. Biol. 7 : 540.
52. Kögl F., Erxleben H., Haagen-Smit A. J. 1934a. Über die Isolierung der Auxine a und b aus pflanzlichen Materialien. 9. Mitteilung über pflanzliche Wachs-tumsstoffe. Hoppe-Seyler's Zeitschrift fur Physiolo-gische Chemie. 225 : 215-229. (In German).
53. Kögl F., Haagen-Smit A. J., Erxleben H. 1933. Über ein phytohormon der zellstreckung. Reindarstellung des auxins aus menschlichem harn. 4. Mitteilung über pflanzliche Wachstumsstoffe. Hoppe-Seyler's Zeit-schrift fur Physiologische Chemie. 214 : 241-261. (In German).
54. Kögl F., Haagen-Smit A. J., Erxleben H. 1934b. Über ein neues Auxin (Heteroauxin) aus Harn. XI. Mitteilung über pflanzliche Wachstumsstoffe. Hoppe-Seyler's Zeitschrift fur Physiologische Chemie. 228 : 90-103. (In German).
55. Korasick, D. A., Enders, T. A., Strader, L. C. 2013. Auxin biosynthesis and storage forms. J. Exp. Bot. 64 : 2541-2555.
56. Kowalczyk S., Jakubowska A., Zielinska E., Bandurski R.S. 2003. Bifunctional indole-3-acetyltransferase catalyses synthesis and hydrolysis of indole-3-myo-inositol in immature endosperm of Zea mays. Physiol. Plant. 119 : 165-174.
57. Last R.L., Bissinger P.H., Mahoney D.J., Radwanski E.R., Fink G.R. 1991. Tryptophan mutants in Ara-bidopsis: the consequences of duplicated tryptophan synthase genes. Plant Cell. 3 : 345-358.
58. Last R.L., Fink G.R. 1988. Tryptophan requiring mutants of the plant Arabidopsis thaliana. Science. 240 : 305-310.
59. LeClere S., Tellez R., Rampey R.A., Matsuda S.P.T., Bartel B. 2002. Characterization of a family of IAA-amino acid conjugate hydrolases from Arabidopsis. J. Biol. Chem. 277 : 20446-20452.
60. Lipetz J., Galston A. W. 1959. Indoleacetic acid oxidase and peroxidase activities in normal and crown-gall tissue cultures of Parthenocissus tricuispidata. Amer. J. Bot. 46: 193-196.
61. Lomax T.L., Muday G.K., Rubery P.H. 1995. Auxin transport. In: Plant Hormones: Physiology, Bio-chemistry, and Molecular Biology (eds. Davies P.J.). Dordrecht : Kluwer, pp. 509-530.
62. Ludwig-Müller J., Epstein E. 1993. Indole-3-butyric acid in Arabidopsis thaliana. II. In vivo metabolism. Plant Growth Regul. 13 : 189-195.
63. Ludwig-Müller J., Hilgenberg W., Epstein E. 1995. The in vitro biosynthesis of indole-3-butyric acid in maize. Phytochem. 40 : 61-68.
64. Ludwig-Müller J. 2011. Auxin conjugates: their role for plant development and in the evolution of land plants. J. Exp. Bot. 62, 6 : 1757-1773.
65. Maher E.P., Martindale S.J. 1980. Mutants of Arabidopsis thaliana with altered responses to auxins and gravity. Biochem. Genet. 18 : 1041-1053.
66. Martinière A., Lavagi I, Nageswaran G, Rolfe D. J., Maneta-Peyret L., Luu D.-T., Botchway S.W., Webb S.E.D., Mongrand S., Maurel C., Martin-Fernandez M.L., Kleine-Vehn J., Friml J., Moreau P., Runion J. 2012. Cell wall constrains lateral diffusion of plant plasma-membrane proteins. Proc. Natl. Acad. Sci. USA 109 : 12805-12810.
67. Michalczuk L., Ribnicky D.M., Cooke T.J., Cohen J.D. 1992. Regulation of indole-3-acetic acid biosynthet-ic pathways in carrotcell cultures. Plant Physiol. 100 : 1346-1353.
68. Morris D.A., Thomas A.G. 1978. A microautoradiographic study of auxin transport in the stem of intact pea seedlings (Pisum sativum L.). J. Exp. Bot. 29 : 147-157.
69. Müller A., Changhui Guan C., Gälweiler L., Tänzler P., Huijser P., Marchant A., Parry G., Bennett M., Wisman E., Palme K. 1998. AtPIN2 defines a locus of Arabidopsis for root gravitropism control. EMBO. J. 17 : 6903-6911.
70. Naramoto S., Otegui M.S., Kutsuna N., de Rycke R., Dainobu T., Karampelias M., Fujimoto M., Feraru E., Miki D., Fukuda H., Nakano A., Friml J. 2014. Insights into the localization and function of the membrane trafficking regulator GNOM ARF-GEF at the Golgi apparatus in Arabidopsis. Plant Cell 26 : 3062-3076.
71. Nonhebel H.M., Cooney T.P., Simpson R. 1993. The route, control and compartmentation of auxin syn-thesis. Aust. J. Plant Physiol. 20 : 527-539.
72. Nonhebel H.M. 1986. Measurement of the rates of ox-indole-3-acetic acid turnover, and indole-3-acetic acid oxidation in Zea mays seedlings. J. Exp. Bot. 37 : 1691-1697.
73. Nonhebel H.M. 2015. Tryptophan-independent indole-3-acetic acid synthesis: critical evaluation of the evi-dence. Plant Physiol. 169 : 1001-1005.
74. Normanly J., Cohen J.D., Fink G.R. 1993. Arabidopsis thaliana auxotrophs reveal a tryptophan-independent biosynthetic pathway for indole-3-acetic acid. Proc. Natl. Acad. Sci. USA. 90 : 10355-10359.
75. Novak O., Henykova E., Sairanen I., Kowalczyk M., Pospisil T., Ljung K. 2012. Tissue-specific profiling of the Arabidopsis thaliana auxin metabolome. Plant J. 72 : 523-536.
76. Nowacki J., Bandurski R.S. 1980. Myo-inositol esters of indole-3-acetic acid as seed auxin precursors of Zea mays L. Plant Physiol. 65 : 422-427.
77. Ӧstin A, Kowalyczk M, Bhalerao RP, Sandberg G. 1998. Metabolism of indole-3-acetic acid in Ara-bidopsis. Plant Physiol. 118 : 285-296.
78. Palme K., Gälweiler L. 1999. PIN-pointing the molecular basis of auxin transport. Current Opinion in Plant Biology. 2 : 375-381.
79. Peer W.A., Cheng Y., Murphy A.S. 2013. Evidence of oxidative attenuation of auxin signalling. J. Exp. Bot. 64 : 2629-2639.
80. Pennazio S. 2002. The discovery of the chemical nature of the plant hormone auxin. Rivista di Biologia. 95 (2) : 289-308.
81. Radwanski E.R., Barczak A.J., Last R.L. 1996. Charac-terization of tryptophan synthase alpha subunit mu-tants of Arabidopsis thaliana. Mol. Gen. Genet. 253 : 353-361.
82. Ribnicky D.M., Ilic N., Cohen J.D., Cooke T.J. 1996. The effects of exogenous auxins on endogenous in-dole-3-acetic acid metabolism: the implications for carrot somatic embryogenesis. Plant Physiol. 112 : 549-558.
83. Rose A.B., Casselman A.L., Last R.L. 1992. A phosphoribosylanthranilate transferase gene is defective in blue fluorescent Arabidopsis thaliana tryptophan mutants. Plant Physiol. 100 : 582-592.
84. Sabater M., Rubery P.H. 1987. Auxin carriers in Cucurbita vesicles. 1. Imposed perturbations of transmembrane pH and electrical potential gradients characterized by radioactive probes. Planta. 171 : 501-506.
85. Sauer M., Kleine-Vehn J. 2019. PIN-FORMED and PIN-LIKES auxin transport facilitators. Development. 146, dev168088.
86. Sherp, A.M., Westfall, C.S., Alvarez, S., Jez, J.M. 2018. Arabidopsis thaliana GH3.15 acyl acid amido syn-thetase has a highly specific substrate preference for the auxin precursor indole-3-butyric acid. J. Biol. Chem. 293 : 4277-4288.
87. Simon S., Skupa P., Viaene T., Zwiewka M., Tejos R., Klima P., Carna M., Rolciik J., De Rycke R., Moreno I., Dobrev P. I., Orellana A., Zazimalova E., Friml J. 2016. PIN6 auxin transporter at endoplasmic reticulum and plasma membrane mediates auxin homeostasis and organogenesis in Arabidopsis. New Phytol. 211 : 65-74.
88. Staswick P.E., Serban B., Rowe M., Tiryaki I., Maldonado M.T., Maldonado M.C., Suza W. 2005. Char-acterization of an Arabidopsis enzyme family that conjugates amino acids to indole-3-acetic acid. Plant Cell. 17 : 616-627.
89. Stepanova A.N., Robertson-Hoyt J., Yun J., Benavente L.M., Xie D.Y., Doležal K., Schlereth A., Jürgens G., Alonso J., 2008. TAA1-mediated auxin biosynthesis is essential for hormone crosstalk and plant development. Cell. 133 : 177-191.
90. Strader L. C., Bartel B. 2011. Transport and metabolism of the endogenous auxin precursor indole-3-butyric acid. Mol. Plant. 4 : 477-486.
91. Strader L.C., Culler A.H., Cohen J.D., Bartel B. 2010. Conversion of endogenous indole-3-butyric acid to indole-3-acetic acid drives cell expansion in Arabidopsis seedlings. Plant Physiol. 153 : 1577-1586.
92. Swarup R., Kargul J., Marchant A., Zadik D., Rah-man A., Mills R., Yemm A., May S., Williams L., Millner P., Tsurumi S., Moore I., Napier R., Kerr I.D., Bennett M.J. 2004. Structure-function analysis of the presumptive Arabidopsis auxin permease AUX1. Plant Cell. 16 : 3069-3083.
93. Swarup R., Péret B. 2012. AUX/LAX family of auxin influx carriers an overview. Front. Plant Sci. 3 : 225. doi: 10.3389/fpls.2012.00225
94. Titapiwatanakun B., Blakeslee J.J., Bandyopadhyay A., Yang H., Mravec J., Sauer M., Cheng Y., Adamec J., Nagashima A., Geisler M., Sakai T., Friml J., Peer W.A., Murphy A.S. 2009. ABCB19/PGP19 stabilises PIN1 in membrane microdomains in Arabidopsis. Plant J. 57 : 27-44.
95. Tognetti V.B., Van Aken O., Morreel K., Vanden-broucke K., van de Cotte B., De Clercq I., Chiwocha S., Fenske R., Prinsen E., Boerjan W., Genty B., Stubbs K.A., Inze D., Van Breusegem F. 2010. Perturbation of indole-3-butyric acid homeostasis by the UDP-glucosyltransferase UGT74E2 modulates Arabidopsis architecture and water stress tolerance. Plant Cell. 22 : 2660-2679.
96. Uzunova V.V., Quareshy M., Del Genio C.I., Napier R.M. 2016. Tomographic docking suggests the mechanism of auxin receptor TIR1 selectivity. Open Biol. 6 : 160139.
97. Wallroth-Marmonr L., Harte C. 1988. IAA in leaves of Antirhinum majus L. Sippe 50 and some mutants. Biologisches Zentralblatt. 197 : 517-531.
98. Wang B., Chu J., Yu T., Xu Q., Sun X., Yuan J., Xiong G., Wang G., Wang Y., Li J. 2015. Tryptophan-independent auxin biosynthesis contributes to early embryogenesis in Arabidopsis. Proc. Natl. Acad. Sci. USA. 112 : 4821-4826.
99. Went F.W. 1926. On growth accelerating substances in the coleoptile of Avena sativa. Proc. Kon. Ned. Akad. Weten. 30 : 1019.
100. Went F.W. 1928. Wuchsstoff und wachstum. Extrait du Recueil des Travaux Botaniques Neerlandais. 25. 116 s.
101. Wright A.D., Sampson M.B., Neuffer M.G., Michalczuk L., Slovin J.P., Cohen J.D. 1991. Indole-3-acetic acid biosynthesis in the mutant maize orange pericarp, a tryptophan auxotroph. Science. 254 : 998-1000.
102. Yamamoto M., Yamamoto K. 1998. Differential effects of 1-naphthaleneacetic acid, indole-3-acetic acid and 2,4-dichlorophenoxyacetic acid on the gravitropic response of roots in an auxin-resistant mutant of Arabidopsis, aux1. Plant Cell Physiol. 39 : 660-664.
103. Yamamoto Y., Kamiya N., Morinaka Y., Matsuoka M., Sazuka T. 2007. Auxin biosynthesis by the YUCCA genes in rice. Plant Physiol. 143 : 1362-1371.
104. Yang Y., Xu R., Ma C.J., Vlot A.C., Klessig D.F., Pich-ersky E. 2008. Inactive methyl indole-3-acetic acid ester can be hydrolyzed and activated by several esterases belonging to the AtMES esterase family of Arabidopsis. Plant physiology. 147 : 1034-1045.
105. Zazímalová E., Murphy A. S., Yang, H., Hoyerova K., Hosek P. 2010. Auxin transporters why so many? Cold Spring Harb. Perspect. Biol. 2, a001552.
106. Zhang J., Peer W.A. 2017. Auxin homeostasis: the DAO of catabolism. J. Exp. Bot. 68 : 3145-3154.
107. Zhao Y., Christensen S.K., Fankhauser C., Cash-man J.R., Cohen J.D., Weigel D., Chory J. 2001. A role for flavin monooxygenase-like enzymes in aux-in biosynthesis. Science. 291 : 306-309.
108. Zhao Y. 2010. Auxin biosynthesis and its role in plant development. Annu. Rev. Plant Biol. 61 : 49-64.
109. Zhao Y. 2012. Auxin biosynthesis: a simple two-step pathway converts tryptophan to indole-3-acetic acid in plants. Mol. Plant. 5 (2) : 334-338.
110. Zhao Y. 2018. Essential roles of local auxin biosynthesis in plant development and in adaptation to environmental changes. Annu. Rev. Plant Biol. 69 : 417-435.
111. Zubieta C., Ross J.R., Koscheski P., Yang Y., Pichersky E., Noel J.P. 2003. Structural basis for substrate recognition in the salicylic acid carboxyl methyltransferase family. Plant Cell. 15 : 1704-1716.