Jasmonates: News on Occurrence, Biosynthesis, Metabolism and Action of an Ancient Group of Signaling Compounds

Abstract

Jasmonic acid (JA) and its related derivatives are ubiquitously occurring compounds of land plants acting in numerous stress responses and development. Recent studies on evolution of JA and other oxylipins indicated conserved biosynthesis. JA formation is initiated by oxygenation of α-linolenic acid (α-LeA, 18:3) or 16:3 fatty acid of chloroplast membranes leading to 12-oxo-phytodienoic acid (OPDA) as intermediate compound, but in Marchantia polymorpha and Physcomitrella patens, OPDA and some of its derivatives are final products active in a conserved signaling pathway. JA formation and its metabolic conversion take place in chloroplasts, peroxisomes and cytosol, respectively. Metabolites of JA are formed in 12 different pathways leading to active, inactive and partially active compounds. The isoleucine conjugate of JA (JA-Ile) is the ligand of the receptor component COI1 in vascular plants, whereas in the bryophyte M. polymorpha COI1 perceives an OPDA derivative indicating its functionally conserved activity. JA-induced gene expressions in the numerous biotic and abiotic stress responses and development are initiated in a well-studied complex regulation by homeostasis of transcription factors functioning as repressors and activators.

Strigolactones enhance root‐knot nematode (Meloidogyne graminicola) infection in rice by antagonizing the jasmonate pathway

“…YFs, young females; Js, juveniles. New Phytologist inactive forms (Wasternack & Strnad, 2018), in nematode-infected roots also correlated with the reduction of bioactive JA-Ile. Upregulation of the SL signaling pathway and suppression of the JA pathway raised the question of whether SLs play a direct role in rice defense against M. graminicola infection.…”

“…We also measured defense hormones and found that the jasmonate levels were strongly reduced in nematode‐infected roots. Accumulation of hydroxylated‐ and carboxylated‐JA–Ile, which seem to be inactive forms (Wasternack & Strnad, ), in nematode‐infected roots also correlated with the reduction of bioactive JA–Ile. Upregulation of the SL signaling pathway and suppression of the JA pathway raised the question of whether SLs play a direct role in rice defense against M. graminicola infection.…”

Peroxisomes: versatile organelles with diverse roles in plants

“…JA is important for plant defense and reproduction (Wasternack & Strnad, 2018). 5) (reviewed in Wasternack & Strnad, 2018). 5) (reviewed in Wasternack & Strnad, 2018).…”

“…Phenotypes of the rice aim1 (abnormal inflorescence meristem 1) mutant in redox gene expression and root development can be rescued by SA treatment, suggesting that rice AIM1whose homolog in Arabidopsis (AtAIM1) is a multifunctional protein (MFP) that is involved in b-oxidationparticipates in SA biosynthesis to regulate ROS concentrations for proper function of the root meristem (Xu et al, 2017). JA is important for plant defense and reproduction (Wasternack & Strnad, 2018). In the octadecanoid pathway for JA biosynthesis, the chloroplast-synthesized JA precursors 12-oxo-phytodienoic acid (OPDA) and dnOPDA are imported into peroxisomes, reduced by OPDA reductase (OPR), and activated to CoA esters that go through the b-oxidation cycles to produce JA ( Fig.…”

“…ACX isoforms important for wound-induced JA biosynthesis have been identified in Arabidopsis, tomato and tea plants (Cruz Castillo et al, 2004;Xin et al, 2019). Other proteins involved in peroxisome biogenesis or boxidation, such as Arabidopsis ACX5, MFP2, KAT2 and PEX6, are also important for JA biosynthesis and, as a result, plant defense and reproduction (Wasternack & Strnad, 2018).…”