Format

Send to

Choose Destination
Plant Physiol. 2017 Jul;174(3):1621-1632. doi: 10.1104/pp.17.00274. Epub 2017 May 22.

Primitive Auxin Response without TIR1 and Aux/IAA in the Charophyte Alga Klebsormidium nitens.

Author information

1
Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan.
2
School of Life Science and Technology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan.
3
RIKEN Center for Sustainable Resource Science, Yokohama, Kanagawa, 230-0045, Japan.
4
Graduate School of Bioscience and Biotechnology, Tokyo Institute of Technology, Yokohama, Kanagawa, 226-8503, Japan ohta.h.ab@m.titech.ac.jp.
5
Japan Science and Technology Agency, Core Research for Evolutional Science and Technology Program, Tokyo, 102-0076, Japan.
6
Earth-Life Science Institute, Tokyo Institute of Technology, Tokyo, 152-8550, Japan.

Abstract

The phytohormone auxin regulates many aspects of growth and development in land plants, but the origin and evolution of auxin signaling and response mechanisms remain largely unknown. Indeed, it remains to be investigated whether auxin-related pathways diverged before the emergence of land plants. To address this knowledge deficit, we analyzed auxin responses in the charophyte alga Klebsormidium nitens NIES-2285, whose ancestor diverged from a green algal ancestor during the evolution of land plants. This strain is the same as Klebsormidium flaccidum NIES-2285, for which the draft genome was sequenced in 2014, and was taxonomically reclassified as K. nitens This genome sequence revealed genes involved in auxin responses. Furthermore, the auxin indole-3-acetic acid (IAA) was detected in cultures of K. nitens, but K. nitens lacks the central regulators of the canonical auxin-signaling pathway found in land plants. Exogenous IAA inhibited cell division and cell elongation in K. nitens Inhibitors of auxin biosynthesis and of polar auxin transport also inhibited cell division and elongation. Moreover, exogenous IAA rapidly induced expression of a LATERAL ORGAN BOUNDARIES-DOMAIN transcription factor. These results suggest that K. nitens has acquired the part of the auxin system that regulates transcription and cell growth without the requirement for the central players that govern auxin signaling in land plants.

PMID:
28533212
PMCID:
PMC5490900
DOI:
10.1104/pp.17.00274
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center