12. Kepinski, S. & Leyser, O. The *Arabidopsis* F-box protein TIR1 is an auxin receptor. *Nature* **435**, 446–451 (2005).

13. Ueguchi, C., Koizumi, H., Suzuki, T. & Mizuno, T. Novel family of sensor histidine kinase genes in *Arabidopsis thaliana*. *Plant Cell Physiol.* **42**, 231–235 (2001).

14. Schlereth, A. et al. MONOPTEROS controls embryonic root initiation by regulating a mobile transcription factor. *Nature* **464**, nature08836 (2010).

15. Marhavý, P. et al. Cytokinin modulates endocytic trafficking of PIN1 auxin efflux carrier to control plant organogenesis. *Dev. Cell* **21**, 796–804 (2011).

16. Marhavý, P. et al. Auxin reflux between the endodermis and pericycle promotes lateral root initiation. *EMBO J.* **32**, 149–158 (2013).

17. Růžička, K. et al. Cytokinin regulates root meristem activity via modulation of the polar auxin transport. *Proc. Natl Acad. Sci. USA* **106**, 4284–4289 (2009).

18. Šimášková, M. et al. Cytokinin response factors regulate PIN-FORMED auxin transporters. *Nat. Commun.* **6**, 8717 (2015).

19. Vanstraelen, M. & Benková, E. Hormonal interactions in the regulation of plant development. *Annu. Rev. Cell Dev. Biol.* **28**, 463–487 (2012).

20. Krouk, G. et al. A framework integrating plant growth with hormones and nutrients. *Trends Plant Sci.* **16**, 178–182 (2011).

21. Sánchez-Rodríguez, C., Rubio-Somoza, I., Sibout, R. & Persson, S. Phytohormones and the cell wall in *Arabidopsis* during seedling growth. *Trends Plant Sci.* **15**, 291–301 (2010).

22. Verma, V., Ravindran, P. & Kumar, P. P. Plant hormone-mediated regulation of stress responses. *BMC Plant Biol.* **16**, 86 (2016).

23. Hurný, A. & Benková, E. Methodological advances in auxin and cytokinin biology. in *Auxins and Cytokinins in Plant Biology* 1–29 (Humana Press, New York, NY, 2017). https://doi.org/10.1007/978-1-4939-6831-2_1.

24. Denancé, N., Sánchez-Vallet, A., Goffner, D. & Molina, A. Disease resistance or growth: the role of plant hormones in balancing immune responses and fitness costs. *Front. Plant Sci.* **4**, 1–12 (2013).

25. Huot, B., Yao, J., Montgomery, B. L. & He, S. Y. Growth-defense tradeoffs in plants: a balancing act to optimize fitness. *Mol. Plant* **7**, 1267–1287 (2014).

26. Boivin, S., Fonouni-Farde, C. & Frugier, F. How auxin and cytokinin phytohormones modulate root microbe interactions. *Front. Plant Sci.* **7**, 1240 (2016).

27. Sabatini, S. et al. An auxin-dependent distal organizer of pattern and polarity in the *Arabidopsis* root. *Cell* **99**, 463–472 (1999).

28. Zürcher, E., Liu, J., di Donato, M., Geisler, M. & Müller, B. Plant development regulated by cytokinin sinks. *Science* **353**, 1027–1030 (2016).

29. Chae, H. S., Faure, F. & Kieber, J. J. The eto1, eto2, and eto3 mutations and cytokinin treatment increase ethylene biosynthesis in *Arabidopsis* by increasing the stability of ACS protein. *Plant Cell* **15**, 545–559 (2003).

30. Raz, V. & Ecker, J. R. Regulation of differential growth in the apical hook of *Arabidopsis*. *Development* **126**, 3661–3668 (1999).

31. Žádník, P. et al. Role of PIN-mediated auxin efflux in apical hook development of *Arabidopsis thaliana*. *Development* **137**, 607–617 (2010).

32. Grendre, E. et al. Cellular basis of hypocotyl growth in *Arabidopsis thaliana*. *Plant Physiol.* **114**, 295–305 (1997).

33. Geldner, N. et al. Rapid, combinatorial analysis of membrane compartments in intact plants with a multicolor marker set. *Plant J.* **59**, 169–178 (2009).

34. Drakakaki, G. et al. Isolation and proteomic analysis of the SYP61 compartment reveal its role in exocytic trafficking in *Arabidopsis*. *Cell Res.* **22**, 413–424 (2012).

35. Gendre, D. et al. Trans-Golgi network localized ECHIDNA/Ypt interacting protein complex is required for the secretion of cell wall polysaccharides in *Arabidopsis*. *Plant Cell* **25**, 2633–2646 (2013).

36. Bassham, D. C., Brandizzi, F., Otegui, M. S. & Sanderfoot, A. A. The secretory system of *Arabidopsis*. *Arab. Book* **6**, e0116 (2008).

37. Früholz, S. & Pimpl, P. Analysis of nanobody-epitope interactions in living cells via quantitative protein transport assays. in *Plant Protein Secretion* 171–182 (Humana Press, New York, NY, 2017). https://doi.org/10.1007/978-1-4939-7262-3_15.

38. Wolf, S. & Greiner, S. Growth control by cell wall pectins. *Protoplasma* **249**, 169–175 (2012).

39. Young, R. E. et al. Analysis of the Golgi apparatus in *Arabidopsis* seed coat cells during polarized secretion of pectin-rich mucilage. *Plant Cell* **20**, 1623–1638 (2008).

40. Mouille, G., Robin, S., Lecomte, M., Pagant, S. & Höfte, H. Classification and identification of *Arabidopsis* cell wall mutants using fourier-transform infrared (FT-IR) microspectroscopy. *Plant J. Cell Mol. Biol.* **35**, 393–404 (2003).

41. Derbyshire, P., McCann, M. C. & Roberts, K. Restricted cell elongation in *Arabidopsis* hypocotyls is associated with a reduced average pectin esterification level. *BMC Plant Biol.* **7**, 31 (2007).

42. Bethke, G. & Glazebrook, J. Measuring pectin properties to track cell wall alterations during plant-pathogen interactions. in *Plant Innate Immunity: Methods and Protocols* (ed. Gassmann, W.) 55–60 (Springer, 2019). https://doi.org/10.1007/978-1-4939-9458-8_6

43. Cosgrove, D. J. Catalysts of plant cell wall loosening. *F1000Research* **5**, 119 (2016).

44. Daher, F. B. & Braybrook, S. A. How to let go: pectin and plant cell adhesion. *Front. Plant Sci.* **6**, 523 (2015).

45. Ando, S. et al. Increase in BrAO1 gene expression and aldehyde oxidase activity during clubroot development in Chinese cabbage (*Brassica rapa* L.). *Mol. Plant Pathol.* **7**, 223–234 (2006).

46. Devos, S., Vissenberg, K., Verbelen, J.-P. & Prinsen, E. Infection of Chinese cabbage by *Plasmodiophora brassicaceae* leads to a stimulation of plant growth: impacts on cell wall metabolism and hormone balance. *New Phytol.* **166**, 241–250 (2005).

47. Schuller, A. & Ludwig-Müller, J. A family of auxin conjugate hydrolases from *Brassica rapa*: characterization and expression during clubroot disease. *New Phytol.* **171**, 145–157 (2006).

48. Siemens, J. et al. Transcriptome analysis of *Arabidopsis* clubroots indicate a key role for cytokinins in disease development. *Mol. Plant. Microbe Interact.* **19**, 480–494 (2006).

49. Knaust, A. & Ludwig-Müller, J. The ethylene signaling pathway is needed to restrict root gall growth in *Arabidopsis* after infection with the obligate biotrophic protist *Plasmodiophora brassicaceae*. *J. Plant Growth Regul.* **32**, 9–21 (2013).

50. Siemens, J., Nagel, M., Ludwig-Müller, J. & Sacristán, M. D. The interaction of *Plasmodiophora brassicaceae* and *Arabidopsis thaliana*: parameters for disease quantification and screening of mutant lines. *J. Phytopathol.* **150**, 592–605 (2002).

51. Müller, B. & Sheen, J. Cytokinin and auxin interaction in root stem-cell specification during early embryogenesis. *Nature* **453**, 1094–1097 (2008).

52. Dello Loio, R. et al. Cytokinins determine *Arabidopsis* root-meristem size by controlling cell differentiation. *Curr. Biol.* **17**, 678–682 (2007).

53. Argyros, R. D. et al. Type B response regulators of *Arabidopsis* play key roles in cytokinin signaling and plant development. *Plant Cell* **20**, 2102–2116 (2008).

54. Dharmasiri, N. et al. Plant development is regulated by a family of auxin receptor F box proteins. *Dev. Cell* **9**, 109–119 (2005).

55. Hutchison, C. E. et al. The *Arabidopsis* histidine phosphotransfer proteins are redundant positive regulators of cytokinin signaling. *Plant Cell* **18**, 3073–3087 (2006).

56. Mason, M. G. Multiple type-B response regulators mediate cytokinin signal transduction in *Arabidopsis*. *Plant Cell* **17**, 3007–3018 (2005).

57. Nishimura, C. et al. Histidine kinase homologs that act as cytokinin receptors possess overlapping functions in the regulation of shoot and root growth in *Arabidopsis*. *Plant Cell* **16**, 1365–1377 (2004).

58. To, J. P. C. & Kieber, J. J. Cytokinin signaling: two-components and more. *Trends Plant Sci.* **13**, 85–92 (2008).

59. Petersson, S. V. et al. An auxin gradient and maximum in the *Arabidopsis* root apex shown by high-resolution cell-specific analysis of IAA distribution and synthesis. *Plant Cell* **21**, 1659–1668 (2009).

60. Brenner, W. G. & Schmülling, T. Transcript profiling of cytokinin action in *Arabidopsis* roots and shoots discovers largely similar but also organ-specific responses. *BMC Plant Biol.* **12**, 112 (2012).

61. Polko, J. K. & Kieber, J. J. The regulation of cellulose biosynthesis in plants. *Plant Cell* **31**, 282–296 (2019).

62. Saffer, A. M. Expanding roles for pectins in plant development. *J. Integr. Plant Biol.* **60**, 910–923 (2018).

63. Bouton, S. et al. QUASIMODO1 encodes a putative membrane-bound glycosyltransferase required for normal pectin synthesis and cell adhesion in *Arabidopsis*. *Plant Cell* **14**, 2577–2590 (2002).

64. Krupková, E., Immerzeel, P., Pauly, M. & Schmülling, T. The TUMOROUS SHOOT DEVELOPMENT2 gene of *Arabidopsis* encoding a putative methyltransferase is required for cell adhesion and co-ordinated plant development. *Plant J. Cell Mol. Biol.* **50**, 735–750 (2007).

65. Mouille, G. et al. Homogalacturonan synthesis in *Arabidopsis thaliana* requires a Golgi-localized protein with a putative methyltransferase domain. *Plant J. Cell Mol. Biol.* **50**, 605–614 (2007).

66. Peaucelle, A., Wightman, R. & Höfte, H. The control of growth symmetry breaking in the *Arabidopsis* hypocotyl. *Curr. Biol.* **25**, 1746–1752 (2015).

67. Phyo, P. et al. Gradients in wall mechanics and polysaccharides along growing inflorescence stems. *Plant Physiol.* **175**, 1593–1607 (2017).

68. Kim, S.-J. & Brandizzi, F. The plant secretory pathway: an essential factory for building the plant cell wall. *Plant Cell Physiol.* **55**, 687–693 (2014).

69. Atmodjo, M. A., Hao, Z. & Mohnen, D. Evolving views of pectin biosynthesis. *Annu. Rev. Plant Biol.* **64**, 747–779 (2013).

70. Ogawa, M., Kay, P., Wilson, S. & Swain, S. M. ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE1 (ADPG1), ADPG2, and QUARTET2 are polygalacturonases required for cell separation during reproductive development in *Arabidopsis*. *Plant Cell* **21**, 216–233 (2009).

71. Peñarrubia, L. et al. Temporal aspects of copper homeostasis and its crosstalk with hormones. *Front. Plant Sci.* **6**, 255 (2015).
12. Kepinski, S. & Leyser, O. The *Arabidopsis* F-box protein TIR1 is an auxin receptor. *Nature* **435**, 446–451 (2005).

13. Ueguchi, C., Koizumi, H., Suzuki, T. & Mizuno, T. Novel family of sensor histidine kinase genes in *Arabidopsis thaliana*. *Plant Cell Physiol.* **42**, 231–235 (2001).

14. Schlereth, A. et al. MONOPTEROS controls embryonic root initiation by regulating a mobile transcription factor. *Nature* **464**, nature08836 (2010).

15. Marhavý, P. et al. Cytokinin modulates endocytic trafficking of PIN1 auxin efflux carrier to control plant organogenesis. *Dev. Cell* **21**, 796–804 (2011).

16. Marhavý, P. et al. Auxin reflux between the endodermis and pericycle promotes lateral root initiation. *EMBO J.* **32**, 149–158 (2013).

17. Růžička, K. et al. Cytokinin regulates root meristem activity via modulation of the polar auxin transport. *Proc. Natl Acad. Sci. USA* **106**, 4284–4289 (2009).

18. Šimášková, M. et al. Cytokinin response factors regulate PIN-FORMED auxin transporters. *Nat. Commun.* **6**, 8717 (2015).

19. Vanstraelen, M. & Benková, E. Hormonal interactions in the regulation of plant development. *Annu. Rev. Cell Dev. Biol.* **28**, 463–487 (2012).

20. Krouk, G. et al. A framework integrating plant growth with hormones and nutrients. *Trends Plant Sci.* **16**, 178–182 (2011).

21. Sánchez-Rodríguez, C., Rubio-Somoza, I., Sibout, R. & Persson, S. Phytohormones and the cell wall in *Arabidopsis* during seedling growth. *Trends Plant Sci.* **15**, 291–301 (2010).

22. Verma, V., Ravindran, P. & Kumar, P. P. Plant hormone-mediated regulation of stress responses. *BMC Plant Biol.* **16**, 86 (2016).

23. Hurný, A. & Benková, E. Methodological advances in auxin and cytokinin biology. in *Auxins and Cytokinins in Plant Biology* 1–29 (Humana Press, New York, NY, 2017). https://doi.org/10.1007/978-1-4939-6831-2_1.

24. Denancé, N., Sánchez-Vallet, A., Goffner, D. & Molina, A. Disease resistance or growth: the role of plant hormones in balancing immune responses and fitness costs. *Front. Plant Sci.* **4**, 1–12 (2013).

25. Huot, B., Yao, J., Montgomery, B. L. & He, S. Y. Growth-defense tradeoffs in plants: a balancing act to optimize fitness. *Mol. Plant* **7**, 1267–1287 (2014).

26. Boivin, S., Fonouni-Farde, C. & Frugier, F. How auxin and cytokinin phytohormones modulate root microbe interactions. *Front. Plant Sci.* **7**, 1240 (2016).

27. Sabatini, S. et al. An auxin-dependent distal organizer of pattern and polarity in the *Arabidopsis* root. *Cell* **99**, 463–472 (1999).

28. Zürcher, E., Liu, J., di Donato, M., Geisler, M. & Müller, B. Plant development regulated by cytokinin sinks. *Science* **353**, 1027–1030 (2016).

29. Chae, H. S., Faure, F. & Kieber, J. J. The eto1, eto2, and eto3 mutations and cytokinin treatment increase ethylene biosynthesis in *Arabidopsis* by increasing the stability of ACS protein. *Plant Cell* **15**, 545–559 (2003).

30. Raz, V. & Ecker, J. R. Regulation of differential growth in the apical hook of *Arabidopsis*. *Development* **126**, 3661–3668 (1999).

31. Žádník, P. et al. Role of PIN-mediated auxin efflux in apical hook development of *Arabidopsis thaliana*. *Development* **137**, 607–617 (2010).

32. Grendre, E. et al. Cellular basis of hypocotyl growth in *Arabidopsis thaliana*. *Plant Physiol.* **114**, 295–305 (1997).

33. Geldner, N. et al. Rapid, combinatorial analysis of membrane compartments in intact plants with a multicolor marker set. *Plant J.* **59**, 169–178 (2009).

34. Drakakaki, G. et al. Isolation and proteomic analysis of the SYP61 compartment reveal its role in exocytic trafficking in *Arabidopsis*. *Cell Res.* **22**, 413–424 (2012).

35. Gendre, D. et al. Trans-Golgi network localized ECHIDNA/Ypt interacting protein complex is required for the secretion of cell wall polysaccharides in *Arabidopsis*. *Plant Cell* **25**, 2633–2646 (2013).

36. Bassham, D. C., Brandizzi, F., Otegui, M. S. & Sanderfoot, A. A. The secretory system of *Arabidopsis*. *Arab. Book* **6**, e0116 (2008).

37. Früholz, S. & Pimpl, P. Analysis of nanobody-epitope interactions in living cells via quantitative protein transport assays. in *Plant Protein Secretion* 171–182 (Humana Press, New York, NY, 2017). https://doi.org/10.1007/978-1-4939-7262-3_15.

38. Wolf, S. & Greiner, S. Growth control by cell wall pectins. *Protoplasma* **249**, 169–175 (2012).

39. Young, R. E. et al. Analysis of the Golgi apparatus in *Arabidopsis* seed coat cells during polarized secretion of pectin-rich mucilage. *Plant Cell* **20**, 1623–1638 (2008).

40. Mouille, G., Robin, S., Lecomte, M., Pagant, S. & Höfte, H. Classification and identification of *Arabidopsis* cell wall mutants using fourier-transform infrared (FT-IR) microspectroscopy. *Plant J. Cell Mol. Biol.* **35**, 393–404 (2003).

41. Derbyshire, P., McCann, M. C. & Roberts, K. Restricted cell elongation in *Arabidopsis* hypocotyls is associated with a reduced average pectin esterification level. *BMC Plant Biol.* **7**, 31 (2007).

42. Bethke, G. & Glazebrook, J. Measuring pectin properties to track cell wall alterations during plant-pathogen interactions. in *Plant Innate Immunity: Methods and Protocols* (ed. Gassmann, W.) 55–60 (Springer, 2019). https://doi.org/10.1007/978-1-4939-9458-8_6

43. Cosgrove, D. J. Catalysts of plant cell wall loosening. *F1000Research* **5**, 119 (2016).

44. Daher, F. B. & Braybrook, S. A. How to let go: pectin and plant cell adhesion. *Front. Plant Sci.* **6**, 523 (2015).

45. Ando, S. et al. Increase in BrAO1 gene expression and aldehyde oxidase activity during clubroot development in Chinese cabbage (*Brassica rapa* L.). *Mol. Plant Pathol.* **7**, 223–234 (2006).

46. Devos, S., Vissenberg, K., Verbelen, J.-P. & Prinsen, E. Infection of Chinese cabbage by *Plasmodiophora brassicaceae* leads to a stimulation of plant growth: impacts on cell wall metabolism and hormone balance. *New Phytol.* **166**, 241–250 (2005).

47. Schuller, A. & Ludwig-Müller, J. A family of auxin conjugate hydrolases from *Brassica rapa*: characterization and expression during clubroot disease. *New Phytol.* **171**, 145–157 (2006).

48. Siemens, J. et al. Transcriptome analysis of *Arabidopsis* clubroots indicate a key role for cytokinins in disease development. *Mol. Plant. Microbe Interact.* **19**, 480–494 (2006).

49. Knaust, A. & Ludwig-Müller, J. The ethylene signaling pathway is needed to restrict root gall growth in *Arabidopsis* after infection with the obligate biotrophic protist *Plasmodiophora brassicaceae*. *J. Plant Growth Regul.* **32**, 9–21 (2013).

50. Siemens, J., Nagel, M., Ludwig-Müller, J. & Sacristán, M. D. The interaction of *Plasmodiophora brassicaceae* and *Arabidopsis thaliana*: parameters for disease quantification and screening of mutant lines. *J. Phytopathol.* **150**, 592–605 (2002).

51. Müller, B. & Sheen, J. Cytokinin and auxin interaction in root stem-cell specification during early embryogenesis. *Nature* **453**, 1094–1097 (2008).

52. Dello Loio, R. et al. Cytokinins determine *Arabidopsis* root-meristem size by controlling cell differentiation. *Curr. Biol.* **17**, 678–682 (2007).

53. Argyros, R. D. et al. Type B response regulators of *Arabidopsis* play key roles in cytokinin signaling and plant development. *Plant Cell* **20**, 2102–2116 (2008).

54. Dharmasiri, N. et al. Plant development is regulated by a family of auxin receptor F box proteins. *Dev. Cell* **9**, 109–119 (2005).

55. Hutchison, C. E. et al. The *Arabidopsis* histidine phosphotransfer proteins are redundant positive regulators of cytokinin signaling. *Plant Cell* **18**, 3073–3087 (2006).

56. Mason, M. G. Multiple type-B response regulators mediate cytokinin signal transduction in *Arabidopsis*. *Plant Cell* **17**, 3007–3018 (2005).

57. Nishimura, C. et al. Histidine kinase homologs that act as cytokinin receptors possess overlapping functions in the regulation of shoot and root growth in *Arabidopsis*. *Plant Cell* **16**, 1365–1377 (2004).

58. To, J. P. C. & Kieber, J. J. Cytokinin signaling: two-components and more. *Trends Plant Sci.* **13**, 85–92 (2008).

59. Petersson, S. V. et al. An auxin gradient and maximum in the *Arabidopsis* root apex shown by high-resolution cell-specific analysis of IAA distribution and synthesis. *Plant Cell* **21**, 1659–1668 (2009).

60. Brenner, W. G. & Schmülling, T. Transcript profiling of cytokinin action in *Arabidopsis* roots and shoots discovers largely similar but also organ-specific responses. *BMC Plant Biol.* **12**, 112 (2012).

61. Polko, J. K. & Kieber, J. J. The regulation of cellulose biosynthesis in plants. *Plant Cell* **31**, 282–296 (2019).

62. Saffer, A. M. Expanding roles for pectins in plant development. *J. Integr. Plant Biol.* **60**, 910–923 (2018).

63. Bouton, S. et al. QUASIMODO1 encodes a putative membrane-bound glycosyltransferase required for normal pectin synthesis and cell adhesion in *Arabidopsis*. *Plant Cell* **14**, 2577–2590 (2002).

64. Krupková, E., Immerzeel, P., Pauly, M. & Schmülling, T. The TUMOROUS SHOOT DEVELOPMENT2 gene of *Arabidopsis* encoding a putative methyltransferase is required for cell adhesion and co-ordinated plant development. *Plant J. Cell Mol. Biol.* **50**, 735–750 (2007).

65. Mouille, G. et al. Homogalacturonan synthesis in *Arabidopsis thaliana* requires a Golgi-localized protein with a putative methyltransferase domain. *Plant J. Cell Mol. Biol.* **50**, 605–614 (2007).

66. Peaucelle, A., Wightman, R. & Höfte, H. The control of growth symmetry breaking in the *Arabidopsis* hypocotyl. *Curr. Biol.* **25**, 1746–1752 (2015).

67. Phyo, P. et al. Gradients in wall mechanics and polysaccharides along growing inflorescence stems. *Plant Physiol.* **175**, 1593–1607 (2017).

68. Kim, S.-J. & Brandizzi, F. The plant secretory pathway: an essential factory for building the plant cell wall. *Plant Cell Physiol.* **55**, 687–693 (2014).

69. Atmodjo, M. A., Hao, Z. & Mohnen, D. Evolving views of pectin biosynthesis. *Annu. Rev. Plant Biol.* **64**, 747–779 (2013).

70. Ogawa, M., Kay, P., Wilson, S. & Swain, S. M. ARABIDOPSIS DEHISCENCE ZONE POLYGALACTURONASE1 (ADPG1), ADPG2, and QUARTET2 are polygalacturonases required for cell separation during reproductive development in *Arabidopsis*. *Plant Cell* **21**, 216–233 (2009).

71. Peñarrubia, L. et al. Temporal aspects of copper homeostasis and its crosstalk with hormones. *Front. Plant Sci.* **6**, 255 (2015).
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101. Klavons, J. A. & Bennett, R. D. Determination of methanol using alcohol oxidase and its application to methyl ester content of pectins. *J. Agric. Food Chem.* **34**, 597–599 (1986).

102. Fang, L. et al. Loss of inositol phosphorylceramide sphingolipid mannosylation induces plant immune responses and reduces cellulose content in *Arabidopsis*. *Plant Cell* **28**, 2991–3004 (2016).

103. Eilers, P. H. C. Parametric time warping. *Anal. Chem.* **76**, 404–411 (2004).

104. Savitzky, Abraham & Golay, M. J. E. Smoothing and differentiation of data by simplified least squares procedures. *Anal. Chem.* **36**, 1627–1639 (1964).

105. Fåhling, M., Graf, H. & Siemens, J. Pathotype separation of *Plasmodiophora brassicae* by the host plant. *J. Phytopathol.* **151**, 425–430 (2003).

## Acknowledgements

We thank Daria Siekhaus, Jiri Friml and Alexander Johnson for critical reading of the manuscript, Peter Pimpl, Christian Luschnig and Liwen Jiang for sharing published material, Lesia Rodriguez Solovey for technical assistance. This work was supported by the Austrian Science Fund (FWF01_11774S) to A.H., K.Ö., and E.B., the German Research Foundation (DFG; He3424/6-1 to I.H.), by the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement n° [291734] (to N.C.), by the EU in the framework of the Marie-Curie FP7 COFUND People Programme through the award of an AgreenSkills+ fellowship No. 609398 (to J.S.) and by the Scientific Service Units of IST-Austria through resources provided by the Bioimaging Facility, the Life Science Facility. The IJPB benefits from the support of Saclay Plant Sciences-SPS (ANR-17-EUR-0007).

## Author contributions

A.H. and E.B. conceived the project; A.H. performed most of experiments related to functional and phenotype analyses of SYACI; C.C. contributed to generation of constructs and transgenic lines; N.C. performed expression analysis of SYACI in wild-type and mutant background in response to hormones; K.Ö. performed Co-IP experiments; J. D. carried out transcriptome profiling; L.D. supported by E.S. and A.H. performed Y2H and BIFC analyses; J.C.M. contributed to α-amyloid assays; M.G. analyzed cell wall mechanical properties; T.R. and H.S. contributed to co-immunolocalisation and phenotype analyses; I.S. and I.H. designed and carried out SYACI expression and phenotype analyses in pollen tubes; R.B. contributed to analyses of SYACI interaction with ECH/YIP complex; A.G. and A.H. performed FT-IR measurements; J.S. and G.M. analyzed composition of cell walls; G.P. and G.D.J. identified SYACI interactors; F.B and J.L-M. tested tolerance of plants to *Plasmodiophora brassicae* infection. A.H. and E.B. wrote the manuscript.

## Competing interests

The authors declare no competing interests.

## Additional information

Supplementary information is available for this paper at https://doi.org/10.1038/s41467-020-15895-5.

Correspondence and requests for materials should be addressed to E.B.

Peer review information *Nature Communications* thanks Yohann Boute and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer review reports are available.

Reprints and permission information is available at http://www.nature.com/reprints

Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

<figure><img src="image_15.png" /></figure>

Open Access This article is licensed under a Creative Commons

Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

© The Author(s) 2020
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## Acknowledgements

We thank Daria Siekhaus, Jiri Friml and Alexander Johnson for critical reading of the manuscript, Peter Pimpl, Christian Luschnig and Liwen Jiang for sharing published material, Lesia Rodriguez Solovey for technical assistance. This work was supported by the Austrian Science Fund (FWF01_11774S) to A.H., K.Ö., and E.B., the German Research Foundation (DFG; He3424/6-1 to I.H.), by the People Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement n° [291734] (to N.C.), by the EU in the framework of the Marie-Curie FP7 COFUND People Programme through the award of an AgreenSkills+ fellowship No. 609398 (to J.S.) and by the Scientific Service Units of IST-Austria through resources provided by the Bioimaging Facility, the Life Science Facility. The IJPB benefits from the support of Saclay Plant Sciences-SPS (ANR-17-EUR-0007).

## Author contributions

A.H. and E.B. conceived the project; A.H. performed most of experiments related to functional and phenotype analyses of SYAC1; C.C. contributed to generation of constructs and transgenic lines; N.C. performed expression analysis of SYAC1 in wild-type and mutant background in response to hormones; K.Ö. performed Co-IP experiments; J. D. carried out transcriptome profiling; L.D. supported by E.S. and A.H. performed Y2H and BIFC analyses; J.C.M. contributed to α-amyloid assays; M.G. analyzed cell wall mechanical properties; T.R. and H.S. contributed to co-immunolocalisation and phenotype analyses; I.S. and I.H. designed and carried out SYAC1 expression and phenotype analyses in pollen tubes; R.B. contributed to analyses of SYAC1 interaction with ECH/YIP complex; A.G. and A.H. performed FT-IR measurements; J.S. and G.M. analyzed composition of cell walls; G.P. and G.D.J. identified SYAC1 interactors; F.B and J.L-M. tested tolerance of plants to *Plasmodiophora brassicae* infection. A.H. and E.B. wrote the manuscript.

## Competing interests

The authors declare no competing interests.

## Additional information

Supplementary information is available for this paper at https://doi.org/10.1038/s41467-020-15895-5.

Correspondence and requests for materials should be addressed to E.B.

Peer review information *Nature Communications* thanks Yohann Boute and the other, anonymous, reviewer(s) for their contribution to the peer review of this work. Peer review reports are available.

Reprints and permission information is available at http://www.nature.com/reprints

Publisher's note Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.

<figure><img src="image_15.png" /></figure>

Open Access This article is licensed under a Creative Commons

Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons license, and indicate if changes were made. The images or other third party material in this article are included in the article's Creative Commons license, unless indicated otherwise in a credit line to the material. If material is not included in the article's Creative Commons license and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this license, visit http://creativecommons.org/licenses/by/4.0/.

© The Author(s) 2020