Overexpression of INCREASED CAMBIAL ACTIVITY, a putative methyltransferase, increases cambial activity and plant growth.
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.
Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea.
Hyunsook
H
Kim
Riken Center for Sustainable Resource Science (CSRS), Tsurumi, Yokohama 230-0045, Japan.
Mikiko
M
Kojima
Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea.
Daeseok
D
Choi
Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea.
Soyoung
S
Park
Synthetic Genomics Research Team, Biomass Research Cooperation Division (BMEP), RIKEN Center for Sustainable Resource Science (CSRS), Tsurumi, Yokohama 230-0045, Japan.
Minami
M
Matsui
Riken Center for Sustainable Resource Science (CSRS), Tsurumi, Yokohama 230-0045, Japan.
Hitoshi
H
Sakakibara
Department of Life Sciences, Pohang University of Science and Technology, Pohang 790-784, Korea. ihwang@postech.ac.kr.
Ildoo
I
Hwang
D017360:Arabidopsis / Q000201:enzymology / Q000235:genetics / Q000254:growth & development / Q000378:metabolism; D029681:Arabidopsis Proteins / Q000235:genetics* / Q000378:metabolism*; D058506:Cambium / Q000235:genetics / Q000254:growth & development; D003583:Cytokinins / Q000378:metabolism; D015870:Gene Expression; D005875:Gibberellins / Q000378:metabolism; D008780:Methyltransferases / Q000235:genetics* / Q000378:metabolism*; D030821:Plants, Genetically Modified / Q000235:genetics / Q000378:metabolism
D029681:Arabidopsis Proteins; D003583:Cytokinins; D005875:Gibberellins; D008780:Methyltransferases
Cambial activity; cytokinin; gibberellin; methanol; methyltransferase; pectin; shoot growth