Abstract
In their natural environment, plants are generally confronted with multiple co-occurring stresses. However, the interaction between stresses is not well known and transcriptomic data in response to combined stresses remain scarce. This study aims at characterizing the interaction between transcriptomic responses to biotic stress and nitrogen (N) limitation. Plants were grown in low or full N, infected or not with Erwinia amylovora (Ea) and plant gene expression was analyzed through microarray and qRT-PCR. Most Ea-responsive genes had the same profile (induced/repressed) in response to Ea in low and full N. In response to stress combination, one third of modulated transcripts responded in a manner that could not be deduced from their response to each individual stress. Many defense-related genes showed a prioritization of their response to biotic stress over their response to N limitation, which was also observed using Pseudomonas syringae as a second pathosystem. Our results indicate an interaction between transcriptomic responses to N and biotic stress. A small fraction of transcripts was prioritized between antagonistic responses, reflecting a preservation of the plant defense program under N limitation. Furthermore, this interaction also led to a complex and specific response in terms of metabolism and cellular homeostasis-associated genes.
Highlights
Sustainable protection of crops is a worldwide necessity
We showed previously that Erwinia amylovora (Ea) can multiply in Arabidopsis and that N supply affects the susceptibility of Arabidopsis to Ea [9]
To determine to what extent the nutritional status of a plant affects its response to a bacterial pathogen, we grew Arabidopsis plants in low (0.5 mM) or full (5 mM) NO3− in plugs of peat moss substrate for 5 weeks (Figure 1A), and infected them with the bacterial phytopathogen Ea
Summary
Plants are often continuously exposed to a broad range of biotic and abiotic stresses in their natural habitats [1]. Because biotic and abiotic stresses significantly reduce plant growth and productivity, considerable research has aimed to determine the responses of plants to single stresses [2]. The response of plants to a combination of stresses is not the simple addition of the response to each single stress [3]. It has been reported that plant responses to different stresses are coordinated by complex and interconnected signaling pathways modulating numerous metabolic networks [4]. Apart from some recent reports, the effects of combined biotic and abiotic stress have been little studied. The exposure of Arabidopsis plants to drought enhances plant susceptibility to an avirulent isolate of Pseudomonas syringae, while it decreases the susceptibility of tomato to the fungus Botrytis cinerea [5]
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