Allantoin, a stress-related purine metabolite, can activate jasmonate signaling in a MYC2-regulated and abscisic acid-dependent manner

Abstract

Allantoin is a metabolic intermediate of purine catabolism that often accumulates in stressed plants. Recently, we used Arabidopsis knockout mutants (aln) of ALLANTOINASE to show that this purine metabolite activates abscisic acid (ABA) production, thereby stimulating stress-related gene expression and enhancing seedling tolerance to abiotic stress. A detailed re-examination of the microarray data of an aln mutant (aln-1) confirmed the increased expression of ABA-related genes and also revealed altered expression of genes involved in jasmonic acid (JA) responses, probably under the control of MYC2, a master switch in the JA signaling pathway. Consistent with the transcriptome profiles, the aln-1 mutant displayed increased JA levels and enhanced responses to mechanical wounding and exogenous JA. Moreover, aln mutants demonstrated modestly increased susceptibility to Pseudomonas syringae and Pectobacterium carotovorum, probably reflecting the antagonistic action of MYC2 on the defense against these bacterial phytopathogens. Exogenously administered allantoin elicited the expression of JA-responsive genes, including MYC2, in wild-type plants, supporting the idea that allantoin might be responsible for the observed JA-related phenotypes of aln mutants. However, mutants deficient in bioactive JA (jar1-1), insensitive to JA (myc2-3), or deficient in ABA (aba2-1 and bglu18) suppressed the effect of exogenous allantoin. The suppression was further confirmed in aln-1 jar1-1 and aln-1 bglu18 double mutants. These results indicate that allantoin can activate the MYC2-regulated JA signaling pathway through ABA production. Overall, this study suggests a possible connection of purine catabolism with stress hormone homeostasis and signaling, and highlights the potential importance of allantoin in these interactions.

Phytohormones in red seaweeds: a technical review of methods for analysis and a consideration of genomic data

“…Despite the presence of polysaccharides distinct from those in terrestrial plants, SPE extraction from red seaweeds and subsequent MS analysis (Mikami et al, 2016) was similar in efficiency to those reported for terrestrial plants (wheat, Iehisa et al 2013Iehisa et al , 2014rice, Tsukahara et al 2015;barley, Rikiishi et al 2015 andHisano et al 2016; Arabidopsis, Lu et al 2015 andTakagi et al 2016). In the course of that work (Mikami et al, 2016), phytohormones were extracted from both lyophilized and fresh seaweed thalli after freezing in liquid nitrogen, which made the fresh samples easier to grind.…”

Trehalose 6-Phosphate Regulates Photosynthesis and Assimilate Partitioning in Reproductive Tissue

“…In particular, SWEET13, 332 which was strongly affected in our study, has been previously singled out as a target 333 for crop improvement in maize (Bezrutczyk et al, 2017). In explaining elevated cadmium and salt, through antioxidant mechanisms (Brychkova et al, 2008), and 345 jasmonic acid and ABA signalling (Takagi et al, 2016). Arabidopsis (Durand et al, 2017).…”

Enhanced Secondary- and Hormone Metabolism in Leaves of Arbuscular Mycorrhizal Medicago truncatula

“…3B), in agreement with the up-regulation of genes involved in ABA biosynthesis and response (Table II). It has been reported that MYC2 functions as a transcriptional activator of ABA signaling in Arabidopsis leaves under abiotic stress (Abe et al, 2003;Takagi et al, 2016). The crosstalk between ABA and JA has been shown to be regulated by MYC2 (Kazan and Manners, 2013).…”