Auxin methylation is required for differential growth in Arabidopsis

Abstract

Asymmetric auxin distribution is instrumental for the differential growth that causes organ bending on tropic stimuli and curvatures during plant development. Local differences in auxin concentrations are achieved mainly by polarized cellular distribution of PIN auxin transporters, but whether other mechanisms involving auxin homeostasis are also relevant for the formation of auxin gradients is not clear. Here we show that auxin methylation is required for asymmetric auxin distribution across the hypocotyl, particularly during its response to gravity. We found that loss-of-function mutants in () prematurely unfold the apical hook, and that their hypocotyls are impaired in gravitropic reorientation. This defect is linked to an auxin-dependent increase in gene expression, leading to an increased polar auxin transport and lack of asymmetric distribution of PIN3 in the mutant. Gravitropic reorientation in the mutant could be restored with either endodermis-specific expression of or partial inhibition of polar auxin transport, which also results in normal gene expression levels. We propose that IAA methylation is necessary in gravity-sensing cells to restrict polar auxin transport within the range of auxin levels that allow for differential responses.

Comparative Transcriptome Analysis of Waterlogging-Sensitive and Tolerant Zombi Pea (Vigna Vexillata) Reveals Energy Conservation and Root Plasticity Controlling Waterlogging Tolerance

“…GO enrichment analysis also suggests the down-regulation of IAA carboxyl methyltransferase activity in WS “Bali” roots (Figure 4). Recently, IAA methylation was proposed to function in maintaining auxin homeostasis by regulating the polar auxin transportation [41]. Moreover, the AUX/IAA family is overrepresented in the upregulated DEGs of “A408” based on Fisher’s exact test for over-representation analysis (Figure 5; Table S4).…”

Differential UVR8 Signal across the Stem Controls UV-B–Induced Inflorescence Phototropism

“…BP reaction was performed according to the standard Invitrogen protocol with a pDONR201 vector (Thermo Fisher Scientific -Life Technologies). The C1 (AT1G09750) and the SCR (AT3G54220) promoters were provided as pENTRP4-P1R-ProC1 (Preuten et al, 2013) and pENTRP4-P1R-ProSCR (Abbas et al, 2018) vectors and were both a kind gift from Miguel Blázquez (Valencia, Spain). LR reaction was performed according to the standard Invitrogen protocol.…”

Auxins and Cytokinins—The Role of Subcellular Organization on Homeostasis

“…There are several reports indicating that methylation of IAA is highly relevant for some plant developmental processes, such as leaf development [ 88 ] and differential growth in the hypocotyl [ 89 ].…”