Jasmonic Acid Modulates Xylem Development by Controlling Expression of PIN-FORMED 7

Abstract

Jasmonic acid (JA) modulates plant development, growth, and responses to stress. Previously, we showed that in Arabidopsis thaliana, JA promotes the formation of extra xylem in roots, and mutant plants unable to express PIN-FORMED 3 (PIN3) and PIN7 formed extra xylem in the absence of exogenous JA. Those results suggested that JA modulates root xylem development by controlling PIN-mediated polar auxin transport. Consistent with this, treatment with an auxin transport inhibitor induced extra xylem formation. Here, we characterized the expression of PIN3 and PIN7 in JA-treated Arabidopsis plants. PIN3 expression was not altered in response to JA; by contrast, PIN7 expression was reduced by JA, which suggested that PIN7 is involved in JA-mediated xylem development. Indeed, overexpressing PIN7 suppressed the formation of extra xylem in response to JA. Based on these results, we propose that JA mediates xylem development by controlling polar auxin transport with PIN7 critically involved in this process.

Transcriptomic Analysis of Radish (Raphanus sativus L.) Spontaneous Tumor

“…The IAA is the main positive regulator of lateral root development, and the genes involved in the biosynthesis, conjugation, transport, and signaling of IAA were downregulated in the tumor tissue compared to the lateral root. In the list of downregulated genes, there were regulators of polar IAA transport: radish homologs of genes encoding IAA efflux protein PIN7, which establishes an apical-basal axis in the embryo and is involved in the pattern specification during root development [ 84 ], as well as AUX1 and LAX3 IAA influx transporters [ 85 ]. Among genes involved in the IAA signaling and downregulated in tumors, there were radish homologs of AUXIN RESPONSE FACTOR 9 ( ARF9) , encoding IAA-regulated TF, and also IAA2 and IAA18 genes encoding transcriptional repressors of Aux/IAA family involved in root development [ 86 , 87 ].…”

Coping With Water Limitation: Hormones That Modify Plant Root Xylem Development

“…The cytokinin biosynthesis mutant log3 log4 has extra protoxylem and a wider xylem axis (De Rybel et al, 2014;Ohashi-Ito et al, 2014), whereas treatment with the synthetic CK, 6-benzylaminopurine (BA) results in loss of protoxylem due to AHP6 suppression (Argyros et al, 2008;Bishopp et al, 2011). JA activates AHP6 expression and suppresses PIN7 expression (Jang et al, 2017(Jang et al, , 2019. Methyl-JA treatment results in extra protoxylem and a wider xylem axis, but mutation in the JA receptor COI does not affect xylem development (Jang et al, 2017).…”

“…Exogenous application of methyl-JA for long periods caused the formation of extra xylem strands by promoting xylem differentiation of procambial cells. This xylem promoting effect of JA was accomplished by interference with the auxin/cytokinin balance within the stele, through ectopic activation of AHP6, which suppresses cytokinin response, and repression of PIN7 expression within the procambial domain (Jang et al, 2017(Jang et al, , 2019. Further, reduced water availability activated the expression of JA responsive genes, LIPOXYGENASE2 (LOX2) and JASMONATE INSENSITIVE 1 (JAI1/MYC2), indicating that during drought stress JA signaling might be another pathway involved in xylem developmental plasticity (Jang and Choi, 2018).…”

Integrative Roles of Phytohormones on Cell Proliferation, Elongation and Differentiation in the Arabidopsis thaliana Primary Root

“…Accordingly, the RNA interference lines of a negative regulator of JA signaling ( JAZ10 ) shows more CSCs differentiation compared to WT plants ( Chen et al, 2011 ). Interestingly, exogenous application of JA reduces the signal of the CK-responsive marker ARR5:GFP in COL ( Jang et al, 2019 ; Vázquez-Chimalhua et al, 2019 ) suggesting an antagonistic crosstalk between JA and CK ( Figure 6C ).…”