Auxin transport and response requirements for root hydrotropism differ between plant species

Yusuke Nakajima, Yoshitaka Nara, Akie Kobayashi, Tomoki Sugita, Yutaka Miyazawa, Nobuharu Fujii, Hideyuki Takahashi

Research output: Contribution to journalArticlepeer-review

18 Citations (Scopus)

Abstract

The direction of auxin transport changes in gravistimulated roots, causing auxin accumulation in the lower side of horizontally reoriented roots. This study found that auxin was similarly involved in hydrotropism and gravitropism in rice and pea roots, but hydrotropism in Lotus japonicus roots was independent of both auxin transport and response. Application of either auxin transport inhibitors or an auxin response inhibitor decreased both hydrotropism and gravitropism in rice roots, and reduced hydrotropism in pea roots. However, Lotus roots treated with these inhibitors showed reduced gravitropism but an unaltered or an enhanced hydrotropic response. Inhibiting auxin biosynthesis substantially reduced both tropisms in rice and Lotus roots. Removing the fnal 0.2 mm (including the root cap) from the root tip inhibited gravitropism but not hydrotropism in rice seedling roots. These results suggested that modes of auxin involvement in hydrotropism differed between plant species. In rice roots, although auxin transport and responses were required for both gravitropism and hydrotropism, the root cap was involved in the auxin regulation of gravitropism but not hydrotropism. Hydrotropism in Lotus roots, however, may be regulated by a novel mechanism that is independent of both auxin transport and the TIR1/AFBs auxin response pathway.

Original languageEnglish
Pages (from-to)3441-3456
Number of pages16
JournalJournal of Experimental Botany
Volume68
Issue number13
DOIs
Publication statusPublished - 2017 Jun 15

Keywords

  • Auxin
  • Gravitropism
  • Hydrotropism
  • Lotus japonicus
  • Pea
  • Rice

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