Osmotic stress inhibits leaf growth of Arabidopsis thaliana by enhancing ARF‐mediated auxin responses

Abstract

We investigated the interaction between osmotic stress and auxin signaling in leaf growth regulation. Therefore, we grew Arabidopsis thaliana seedlings on agar media supplemented with mannitol to impose osmotic stress and 1-naphthaleneacetic acid (NAA), a synthetic auxin.We performed kinematic analysis and flow-cytometry to quantify the effects on cell division and expansion in the first leaf pair, determined the effects on auxin homeostasis and response (DR5::b-glucuronidase), performed a next-generation sequencing transcriptome analysis and investigated the response of auxin-related mutants.Mannitol inhibited cell division and expansion. NAA increased the effect of mannitol on cell division, but ameliorated its effect on expansion. In proliferating cells, NAA and mannitol increased free IAA concentrations at the cost of conjugated IAA and stimulated DR5 promotor activity. Transcriptome analysis shows a large overlap between NAA and osmotic stress-induced changes, including upregulation of auxin synthesis, conjugation, transport and TRANSPORT INHIBITOR RESPONSE1 (TIR1) and AUXIN RESPONSE FACTOR (ARF) response genes, but downregulation of Aux/IAA response inhibitors. Consistently, arf7/19 double mutant lack the growth response to auxin and show a significantly reduced sensitivity to osmotic stress.Our results show that osmotic stress inhibits cell division during leaf growth of A. thaliana at least partly by inducing the auxin transcriptional response.

Potassium Chloroaurate-Mediated In Vitro Synthesis of Gold Nanoparticles Improved Root Growth by Crosstalk with Sucrose and Nutrient-Dependent Auxin Homeostasis in Arabidopsis thaliana

“…There were significant reductions (~43-47%) in the shoot area of the seedlings grown in NR.IAA, NR.NAA and NR.2,4-D compared with NR (Figure 5A,B). The results are coherent with earlier studies reporting the inhibitory effects of IAA, NAA, and 2,4-D on the growth and development of Arabidopsis leaves [54][55][56]. When the seedlings were grown in NR.IAA.KAuCl 4 and NR.NAA.KAuCl 4 , shoot area increased significantly (~17-32%) compared with NR.IAA, NR.NAA, respectively (Figure 5A,B).…”

De novo transcriptome sequencing of Capsicum frutescens. L and comprehensive analysis of salt stress alleviating mechanism by Bacillus atrophaeusWU‐9

“…The DEGs implicated in “plant hormone signal transduction” and “MAPK signaling pathway‐plant” pathways were significantly enriched in salt‐treated seedlings compared with controls (Figure S12). Previous research revealed that the plant hormone auxin controls growth and developmental responses throughout the life of plants, and the key genes, AUX1, AUX/IAA, TIR1, ARF, GH3, and SAUR, display identical differential expression profiles to auxin transduction pathway (Kalve et al, 2020; Wang et al, 2020). WU‐9 inoculation‐regulated genes mainly involved in hormones, including auxin (AUX/IAA, auxin‐responsive GH3 and SUAR), abscisic acid (ABF), and ethylene (ETR) in “plant hormone signaling” pathways (Figure S8B).…”

Auxin/Cytokinin Antagonistic Control of the Shoot/Root Growth Ratio and Its Relevance for Adaptation to Drought and Nutrient Deficiency Stresses

“…The increased lateral-root-growth response to drought stress was shown to depend on auxin regulation at the biosynthesis, transport, and signaling levels [82]. Moreover, osmotic stress was shown to inhibit leaf expansion growth by increased auxin action via the ARF family of auxin response activators, indicating that auxin also mediates drought stress responses in the shoot [84]. Auxin may also positively impact drought tolerance by limiting stomatal density and controlling stomatal aperture [85].…”