J Integr Plant Biol. ›› 2016, Vol. 58 ›› Issue (11): 874-889.DOI: 10.1111/jipb.12486

Special Issue: Cell Biology and Functions

• Cell and Developmental Biology •     Next Articles

Overexpression of INCREASED CAMBIAL ACTIVITY, a putative methyltransferase, increases cambial activity and plant growth

Hyunsook Kim1, Mikiko Kojima3, Daeseok Choi1, Soyoung Park1, Minami Matsui2, Hitoshi Sakakibara3 and Ildoo Hwang1*   

  1. 1Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea
    2Synthetic Genomics Research Team, Biomass Research Cooperation Division (BMEP), RIKEN Center for Sustainable Resource Science (CSRS), Tsurumi, Yokohama 230-0045, Japan
    3Riken Center for Sustainable Resource Science (CSRS), Tsurumi, Yokohama 230-0045, Japan
  • Received:2016-04-22 Accepted:2016-06-20 Published:2016-06-20
  • About author:*Correspondence: E-mail: Ildoo Hwang (ihwang@postech.ac.kr)

Abstract:

Cambial activity is a prerequisite for secondary growth in plants; however, regulatory factors controlling the activity of the secondary meristem in radial growth remain elusive. Here, we identified INCREASED CAMBIAL ACTIVITY (ICA), a gene encoding a putative pectin methyltransferase, which could function as a modulator for the meristematic activity of fascicular and interfascicular cambium in Arabidopsis. An overexpressing transgenic line, 35S::ICA, showed accelerated stem elongation and radial thickening, resulting in increased accumulation of biomass, and increased levels of cytokinins (CKs) and gibberellins (GAs). Expression of genes encoding pectin methylesterases involved in pectin modification together with pectin methyltransferases was highly induced in 35S::ICA, which might contribute to an increase of methanol emission as a byproduct in 35S::ICA. Methanol treatment induced the expression of GA- or CK-responsive genes and stimulated plant growth. Overall, we propose that ectopic expression of ICA increases cambial activity by regulating CK and GA homeostasis, and methanol emission, eventually leading to stem elongation and radial growth in the inflorescence stem.

Key words: Cambial activity, cytokinin, gibberellin, methanol, methyltransferase, pectin, shoot growth

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