“Salicylic Acid Mutant Collection” as a Tool to Explore the Role of Salicylic Acid in Regulation of Plant Growth under a Changing Environment

Abstract

The phytohormone salicylic acid (SA) has a crucial role in plant physiology. Its role is best described in the context of plant response to pathogen attack. During infection, SA is rapidly accumulated throughout the green tissues and is important for both local and systemic defences. However, some genetic/metabolic variations can also result in SA overaccumulation in plants, even in basal conditions. To date, more than forty Arabidopsis thaliana mutants have been described as having enhanced endogenous SA levels or constitutively activated SA signalling pathways. In this study, we established a collection of mutants containing different SA levels due to diverse genetic modifications and distinct gene functions. We chose prototypic SA-overaccumulators (SA-OAs), such as bon1-1, but also “non-typical” ones such as exo70b1-1; the selection of OA is accompanied by their crosses with SA-deficient lines. Here, we extensively studied the plant development and SA level/signalling under various growth conditions in soil and in vitro, and showed a strong negative correlation between rosette size, SA content and PR1/ICS1 transcript signature. SA-OAs (namely cpr5, acd6, bon1-1, fah1/fah2 and pi4kβ1β2) had bigger rosettes under high light conditions, whereas WT plants did not. Our data provide new insights clarifying a link between SA and plant behaviour under environmental stresses. The presented SA mutant collection is thus a suitable tool to shed light on the mechanisms underlying trade-offs between growth and defence in plants.

Salicylic Acid Signalling in Plants

“…The mutant collection presented by Pluhařová and co-workers provides a very valuable tool to better understand the mechanisms underlying trade-offs between growth and defence in plants. The authors present a novel research study, providing new insights clarifying a link between SA and plant behaviour under environmental stresses [24]. They showed a negative correlation between the SA content and the rosette size, but not the root growth.…”

“…These papers cover a wide range of aspects of SA-related mechanisms. They include a "classical" demonstration of the importance of SA in biotic stress [23] and the importance of the use of various mutants related to SA signalling [24,25], as well as focus on the crosstalk with other stress-related compounds [25,26]. There are also works investigating the effects of environmental factors on the SA-related signalling [26,27], and on the role of different SA analogue compounds [28].…”

ACCELERATED CELL DEATH 6 Acts on Natural Leaf Senescence and Nitrogen Fluxes in Arabidopsis

“…A complex network of regulatory pathways fine tunes the timing of the plant senescence in response to both external and internal clues, such as plant pathogen, nutrient starvation, and phytohormones, including abscisic acid, jasmonic acid, ethylene, and SA. For instance, SA levels in leaves participates to the natural senescence by regulating the expression of genes that are also modified by abiotic stresses (Morris et al, 2000;Lim et al, 2007). Following the N percentage in leaves and the N remobilization from the leaves to the seeds, we provided evidence that ACD6 acts on N mobilization during leaf senescence (Figures 4A,C).…”

“…Little is known about the molecular function of ACD6 protein ( Lu et al, 2005 ). Nevertheless, it has been demonstrated that the ACD6 protein plays a major role in plant response to biotic and abiotic stresses through the SA signaling pathway ( Rate et al, 1999 ; Todesco et al, 2014 ; Pluhařová et al, 2019 ). During pathogen infection, the rise in SA levels in leaves triggers the cell death program and leaf necrosis.…”

Disrupted actin: a novel player in pathogen attack sensing?

“…Indeed, many plants with altered immune pathways exhibit strong pleiotropic phenotypes, including growth retardation (Rate et al , 1999; Yi & Richards, 2008). The behaviour of those plants is thus significantly affected by hormonal misregulation, especially SA increase (Pluharova et al , 2019). The crossing of those mutants will bring new biases that need to be carefully interpreted.…”