Jasmonoyl isoleucine accumulation is needed for abscisic acid build‐up in roots of Arabidopsis under water stress conditions

Abstract

Phytohormones are central players in sensing and signalling numerous environmental conditions like drought. In this work, hormone profiling together with gene expression of key enzymes involved in abscisic acid (ABA) and jasmonate biosynthesis were studied in desiccating Arabidopsis roots. Jasmonic acid (JA) content transiently increased after stress imposition whereas progressive and concomitant ABA and Jasmonoyl Isoleucine (JA-Ile) accumulations were detected. Molecular data suggest that, at least, part of the hormonal regulation takes place at the biosynthetic level. These observations also point to a possible involvement of jasmonates on ABA biosynthesis under stress. To test this hypothesis, mutants impaired in jasmonate biosynthesis (opr3, lox6 and jar1-1) and in JA-dependent signalling (coi1) were employed. Results showed that the early JA accumulation leading to JA-Ile build up was necessary for an ABA increase in roots under two different water stress conditions. Signal transduction between water stress-induced JA-Ile accumulation and COI1 is necessary for a full induction of the ABA biosynthesis pathway and subsequent hormone accumulation in roots of Arabidopsis plants. The present work adds a level of interaction between jasmonates and ABA at the biosynthetic level.

Jasmonic acid interacts with abscisic acid to regulate plant responses to water stress conditions

“…7 In a previous publication it was shown that jasmonates and in particular Jasmonic acid Isoleucine (JA-Ile) accumulation and, hence JA-dependent signaling, was necessary for consistent ABA accumulation in roots of Arabidopsis. 8 Although plants defective in JA-Ile accumulation (jar1-1) and JA-Ile dependent signaling (coi1-16) were able to accumulate ABA in roots after dehydration, accumulation was significantly lower compared to their respective WT. Interestingly, in complementary experiments using the same system, JA transiently accumulates in roots of dehydrated plants but this increase is coupled with a decrease in the hormone concentration in shoots.…”

Metabolomics of Disease Resistance in Crops

“…A central molecule is 13-hydroperoxy octadecatrienoic acid (13-HPOT) that can be further metabolized into 13-keto octadecatrienoic acid, cleaved into n-hexenal, or diverted into jasmonate biosynthetic pathway (Schaller, 2001). Besides jasmonates that do have a role in stress responses (De Ollas et al, 2015), fatty acid hydroperoxides have been shown to have a role in the induction of HR after pathogen attack (Dat et al, 2005;Zoeller et al, 2012) although cell death is not always associated with lipid peroxidation (Dat et al, 2005). In animal systems, lipid signaling plays an important role in the development of inflammatory response.…”

“…Citrus produce a large number of triterpenoids that have been associated to fruit and juice quality as well as responses of vegetative tissues to the environment. These compounds are synthesized from squalene by formation of a polycyclic molecule containing a furanolactone core structure; the main representative is limonin and its respective glucosylated form (Arbona et al, 2015). These compounds have been found to accumulate in vegetative Citrus tissues in response to HLB and could be part of the metabolic defense response (Manthey, 2008;Slisz et al, 2012).…”

“…In addition, these instruments also allow fragmentation of selected compounds, thanks to the presence of a quadrupole segment and a collision cell before the flight tube, to gain structural information. This configuration is usually sufficient to analyze different types of secondary metabolites: flavonoids and triterpenoids (Arbona et al, 2015;Böttcher et al, 2008), phenolics (Böttcher et al, 2009a), glucosinolates and related compounds (Böttcher et al, 2009b;Zandalinas et al, 2012), lipids (Zoeller et al, 2012), etc...Due to the high specificity of secondary metabolites and the little information available on them (mass spectra, fragmentation pattern, elution time, etc...), together with the poor cross-platform exchangeability of LC/MS data, make very often necessary their de novo identification using in-house built databases or matching the annotation (MS spectra and retention time) with pure standards. For these reasons, ensuring high quality spectral information is of key importance to facilitate mass spectra curation and interpretation (Figure 1).…”

Differential gene expression in response to cold stress in Viola wittrockiana

“…On the assumption that the existence of tRNA-Ile is related to the presence of isoleucine in cells, Mayer et al (1990) showed that the rate of isoleucine synthesis increased up to 6-fold in cowpea plants under heat shock conditions. Also, it has been found that the presence of compounds such as jasmo-noyl-isoleucine is required to synthesize abscisic acid (ABA) in Arabidopsis thaliana roots under drought stress conditions (Ollas et al, 2015). ABA is a growth regulator which is known to be responsive to osmotic and cold stresses in plants (Ishitani et al, 1997).…”