The possible action mechanisms of indole-3-acetic acid methyl ester in Arabidopsis.
We previously reported that Arabidopsis indole-3-acetic acid (IAA)-methyltransferase-1 (IAMT1) catalyzes the conversion of IAA, an essential phytohormone, to methyl-IAA (MeIAA) and that IAMT1 plays an important role in leaf development. Here, we present the possible mechanisms of action of MeIAA in Arabidopsis. We showed that MeIAA was more potent than IAA in the inhibition of hypocotyl elongation and that MeIAA and naphthalene-acetic acid (NAA), but not IAA, rescued the hypocotyl gravitropic defects in dark-grown aux1. However, MeIAA was less potent than IAA in the inhibition of primary root elongation in light-grown seedlings, and could not rescue the agravitropic root phenotype of aux1. MeIAA had a stronger capacity to induce lateral roots than both IAA and NAA and rescued the defective lateral root phenotype of aux1 seedlings. However, its capacity to induce root hairs was weaker than IAA and NAA and did not rescue the defective root hair phenotype of aux1 seedlings. These data indicate that MeIAA is an inactive form of IAA. The different sensitivities to MeIAA among different organs probably resulted from different expression localization and capacities of a putative MeIAA esterase to convert MeIAA to IAA.
Li
Linchuan
L
National Laboratory for Protein Engineering and Plant Genetic Engineering, Peking-Yale Joint Research Center for Plant Molecular Genetics and AgroBiotechnology, College of Life Sciences, Peking University, Beijing, PR China.
Hou
Xianhui
X
Tsuge
Tomohiko
T
Ding
Maoyu
M
Aoyama
Takashi
T
Oka
Atsuhiro
A
Gu
Hongya
H
Zhao
Yunde
Y
Qu
Li-Jia
LJ
D017360:Arabidopsis / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D018522:Gravitropism / Q000187:drug effects* / Q000235:genetics / Q000502:physiology; D018546:Hypocotyl / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D007210:Indoleacetic Acids / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018517:Plant Roots / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified
D007210:Indoleacetic Acids; D010940:Plant Proteins; C030737:indoleacetic acid