The possible action mechanisms of indole-3-acetic acid methyl ester in Arabidopsis

Abstract

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.

DELLA-Induced Early Transcriptional Changes during Etiolated Development in Arabidopsis thaliana

“…Among the relevant targets for GAI, we identified several genes related to auxin synthesis and signaling, such as the negative auxin signaling intermediates AUXIN/INDOLE-3-ACETIC ACID19 ( Aux/IAA19 ) [53] and Aux/IAA29 , two auxin-inducible SMALL AUXIN UPREGULATED genes, and also INDOLE-3-ACETIC ACID METHYLTRANSFERASE1 ( IAMT1 ) [54] and YUCCA3 ( YUC3 ) involved in IAA inactivation [55] and biosynthesis [56], respectively (Table 1 and Table S1). The ethylene biosynthesis genes ACC SYNTHASE8 ( ACS8 ) and ACS5/ETO2 [57], [58] were also among the genes downregulated by GAI, extending the control by GAs to hormones other than auxin.…”

Auxin Biosynthesis and Its Role in Plant Development

“…It is likely that multiple pathways contribute to de novo auxin production. IAA can also be released from IAA conjugates by hydrolytic cleavage of IAA-amino acids, IAA-sugar, and IAA-methyl ester (3, 36, 67, 72). Furthermore, although plants share evolutionary conserved core mechanisms for auxin biosynthesis, different plant species may also have unique strategies and modifications to optimize their IAA biosynthesis.…”

ceRNA Cross-Talk in Paulownia Witches’ Broom Disease

“…IAA-methyltransferase-1 (IAMT1) could convert IAA to methyl-IAA and IAMT1 is an essential regulator of leaf development [51]. IAMT1 (EVM0021401.1) was found in this part of the network.…”