Arabidopsis petiole torsions induced by lateral light or externally supplied auxin require microtubule-associated TORTIFOLIA1/SPIRAL2
- 183 Downloads
Although rather inconspicuous, movements are an important adaptive trait of plants. Consequently, light- or gravity-induced movements leading to organ bending have been studied intensively. In the field, however, plant movements often result in organ twisting rather than bending. This study investigates the mechanism of light- or gravity-induced twisting movements, coined “helical tropisms.” Because certain Arabidopsis cell expansion mutants show organ twisting under standard growth conditions, we here investigated how the right-handed helical growth mutant tortifolia1/spiral2 (tor1) responds when stimulated to perform helical tropisms. When leaves were illuminated from the left, tor1 was capable of producing left-handed petiole torsions, but these occurred at a reduced rate. When light was applied from right, tor1 plants rotated their petioles much faster than the wild-type. Applying auxin to the lateral-distal side of wild-type petioles produced petiole torsions in which the auxinated flank was consistently turned upwards. This kind of movement was not observed in tor1 mutants when auxinated to produce left-handed movements. Investigating auxin transport in twisting petioles based on the DR5-marker suggested that auxin flow was apical-basal rather than helical. While cortical microtubules of excised wild-type petioles oriented transversely when stimulated with auxin, those of tor1 were largely incapable of reorientation. Together, our results show that tor1 is a tropism mutant and suggest a mechanism in which auxin and microtubules both contribute to helical tropisms.
KeywordsMicrotubule Tropism tortifolia1/spiral2 Petiole Helical growth Auxin
The research was supported by a grant to H.B. by the DFG (Deutsche Forschungsgemeinschaft; BU 2301/2-1) and by the local Sonderforschungsbereich 944 (also DFG). We are also grateful to Sabine Zachgo for ongoing support.
Compliance with ethical standards
Conflict of interest
The authors declare that they have no competing interests.
- Bürger D (1971) Die morphologischen Mutanten des Göttinger Arabidopsis-Sortiments, einschließlich der Mutanten mit abweichender Samenfarbe. Arabid Inf Serv 8:36–42Google Scholar
- Buschmann H, Hauptmann M, Niessing D, Lloyd CW, Schaffner AR (2009) Helical growth of the Arabidopsis mutant tortifolia2 does not depend on cell division patterns but involves handed twisting of isolated cells. Plant Cell 21(7):2090–2106. https://doi.org/10.1105/tpc.108.061242 CrossRefPubMedPubMedCentralGoogle Scholar
- Buschmann H, Dols J, Kopischke S, Peña EJ, Andrade-Navarro MA, Heinlein M, Szymanski DB, Zachgo Z, Doonan JH, Lloyd CW (2015) Arabidopsis KCBP interacts with AIR9 but stays in the cortical division zone throughout mitosis via its MyTH4-FERM domain. J Cell Sci 128:2033–2046. https://doi.org/10.1242/jcs.156570 CrossRefPubMedGoogle Scholar
- Lindeboom JJ, Nakamura M, Hibbel A, Shundyak K, Gutierrez R, Ketelaar T, Emons AMC, Mulder BM, Kirik V, Ehrhardt DW (2013) A mechanism for reorientation of cortical microtubule arrays driven by microtubule severing. Science 342(6163):1202–1205. https://doi.org/10.1126/Science.1245533 CrossRefGoogle Scholar
- Reinholz E (1947) Auslösung von Röntgen-Mutationen bei Arabidopsis thaliana (L.) HEYNH. und ihre Bedeutung für die Pflanzenzüchtung und Evolutionstheorie. FIAT Rep 1006:1–70Google Scholar
- Snow R (1962) Geostrophism. In: Ruhland W (ed) Physiology of movements, encyclopedia of plant physiology. Springer, Berlin, pp 378–389Google Scholar
- Zachgo S (2002) In situ hybridization. In: Gillmartin P, Bowler C (eds) Molecular plant biology: a practical approach vol. 2, vol practical approach series. IRL Press, OxfordGoogle Scholar