Mycorrhizal tomato plants fine tunes the growth‐defence balance upon N depleted root environments

Abstract

In low nutritive environments, the uptake of N by arbuscular mycorrhizal (AM) fungi may confer competitive advantages for the host. The present study aims to understand how mycorrhizal tomato plants perceive and then prepare for an N depletion in the root environment. Plants colonized by Rhizophagus irregularis displayed improved responses to a lack of N than nonmycorrhizal (NM) plants. These responses were accomplished by a complex metabolic and transcriptional rearrangement that mostly affected the gibberellic acid and jasmonic acid pathways involving DELLA and JAZ1 genes, which were responsive to changes in the C/N imbalance of the plant. N starved mycorrhizal plants showed lower C/N equilibrium in the shoots than starved NM plants and concomitantly a downregulation of the JAZ1 repressor and the increased expression of the DELLA gene, which translated into a more active oxylipin pathway in mycorrhizal plants. In addition, the results support a priorization in AM plants of stress responses over growth. Therefore, these plants were better prepared for an expected stress. Furthermore, most metabolites that were severely reduced in NM plants following the N depletion remained unaltered in starved AM plants compared with those normally fertilized, suggesting that the symbiosis buffered the stress, improving plant development in a stressed environment.

Distinct gene expression and secondary metabolite profiles insuppressor of prosystemin-mediated responses2 (spr2)tomato mutants having impaired mycorrhizal colonization

“…Since spr2 mutants are impaired in the orchestration of the JA burst required for the activation of wound-and systemin-related defense responses (Li et al, 2003), it may be argued that AMF promote along-term maintenance of constitutively higher JA levels as a strategy to ensure efficient root colonization. This is in accordance with different scales of AMF-associated JA accumulation previously reported in various plant models, including tomato (Hause et al, 2007;Hause & Schaarschmidt, 2009;López-Ráez et al, 2010;Sánchez-Bel et al, 2016). A plausible use of this strategy could be to orchestrate a JA-related suppression of immunity responses triggered by microbe-associated molecular patterns in order to enhance a positive plant-microorganism interaction, as previously observed in Arabidopsis roots (Jacobs et al, 2011;Lakshmanan et al, 2012).…”

“…Full-size  DOI: 10.7717/peerj.8888/ fig-4 Floss & Walter, 2009;Whiteside, Garcia & Treseder, 2012;Jiménez-Bremont et al, 2014;Rivero et al, 2015;Bedini et al, 2018;Sánchez-Bel et al, 2018;Liao et al, 2018). A targeted assay focusing on the analysis of the tomatine biosynthetic pathway (Montero-Vargas et al, 2018) was performed.…”

Distinct branches of the N‐end rule pathway modulate the plant immune response

“…Quantitative RT-PCR was performed as previously described for Arabidopsis (Gibbs et al, 2014b) and barley (Mendiondo et al, 2016). Proteomics (Vu et al, 2016) and metabolomics (Gamir et al, 2012;S anchez-Bel et al, 2018) analyses were carried out as previously described.…”

LOL2 and LOL5 loci control latex production by laticifer cells in Euphorbia lathyris

“…The extraction and quantification were performed as described in Sanchez‐Bel et al . (). Three biological replicates were used for each genotype, each biological replicate being a pool of three plants.…”

“…Plant hormone JA-Ile was quantified by a liquid chromatography system (UPLC, Waters) connected to a triple quadrupole mass spectrometer (TQD, Waters) using as standard JA-Ile-d 6 . The extraction and quantification were performed as described in Sanchez-Bel et al (2018). Three biological replicates were used for each genotype, each biological replicate being a pool of three plants.…”