Global profiling of phytohormone dynamics during combined drought and pathogen stress in Arabidopsis thaliana reveals ABA and JA as major regulators

Abstract

Global transcriptome studies demonstrated the existence of unique plant responses under combined stress which are otherwise not seen during individual stresses. In order to combat combined stress plants use signaling pathways and ‘cross talk’ mediated by hormones involved in stress and growth related processes. However, interactions among hormones’ pathways in combined stressed plants are not yet known. Here we studied dynamics of different hormones under individual and combined drought and pathogen infection in Arabidopsis thaliana by liquid chromatography-mass spectrometry (LC-MS) based profiling. Our results revealed abscisic acid (ABA) and salicylic acid (SA) as key regulators under individual drought and pathogen stress respectively. Under combined drought and host pathogen stress (DH) we observed non-induced levels of ABA with an upsurge in SA and jasmonic acid (JA) concentrations, underscoring their role in basal tolerance against host pathogen. Under a non-host pathogen interaction with drought (DNH) stressed plants, ABA, SA and JA profiles were similar to those under DH or non-host pathogen alone. We propose that plants use SA/JA dependent signaling during DH stress which antagonize ABA biosynthesis and signaling pathways during early stage of stress. The study provides insights into hormone modulation at different time points during combined stress.

Reactive oxygen species and reactive carbonyl species constitute a feed‐forward loop in auxin signaling for lateral root formation

“…The pellet was washed with 80% acetonitrile containing 1% acetic acid and the resulting supernatant was mixed with the first supernatant. Finally, the supernatants were successively pre-treated and their IAA contents were determined as described previously (Gupta et al, 2017).…”

The role of water in plant–microbe interactions

“…However, increased ABA levels are associated with enhanced susceptibility to Pst DC3000 in Arabidopsis at the post-invasive stage (de Torres-Zabala et al, 2007). Interestingly, when Arabidopsis plants are challenged with drought and pathogen simultaneously, ABA level remains unchanged but the levels of defense hormones SA and JA are raised, providing an explanation for why the combined stress leads to enhanced disease resistance in Arabidopsis (Gupta et al, 2017). In addition, drought-stressed chickpea exhibits higher resistance to a xylem-inhabiting bacterial pathogen, Ralstonia solanacearum (Sinha et al, 2016).…”

Plant responses underlying nonhost resistance of Citrus limon against Xanthomonas campestris pv. campestris

“…Interestingly, several ABA‐related genes, including NCED3 , were found to be down‐regulated in C. sinensis NHR to Xcv , and this was also associated with a strong decrease in ABA levels at early times post‐inoculation (Petrocelli et al ., ). In Arabidopsis and rice, several reports have shown that ABA accumulation induced by bacterial pathogens promotes susceptibility via the suppression of the accumulation of phenolic compounds through phenylalanine ammonia‐lyase (PAL) inhibition, callose deposition and also SA‐mediated defences, contributing to symptom development (Gupta et al ., ; Lievens et al ., ; de Torres Zabala et al ., ; Xu et al ., ). However, ABA can also positively influence disease resistance by regulating stomatal closure (Lim et al ., ).…”