Salicylic acid, a multifaceted hormone to combat disease.

For more than 200 years, the plant hormone salicylic acid (SA) has been studied for its medicinal use in humans. However, its extensive signaling role in plants, particularly in defense against pathogens, has only become evident during the past 20 years. This review surveys how SA in plants regulates both local disease resistance mechanisms, including host cell death and defense gene expression, and systemic acquired resistance (SAR). Genetic studies reveal an increasingly complex network of proteins required for SA-mediated defense signaling, and this process is amplified by several regulatory feedback loops. The interaction between the SA signaling pathway and those regulated by other plant hormones and/or defense signals is also discussed

Nitric oxide: A new player in plant signalling and defence responses.

There is increasing evidence that nitric oxide (NO), which was first identified as a unique diffusible molecular messenger in animals, plays important roles in diverse (patho)physiological processes in plants. NO functions include the modulation of hormonal, wounding and defence responses, as well as the regulation of cell death. Enzymes that catalyse NO synthesis and signalling cascades that mediate NO effects have recently been discovered, providing a better understanding of the mechanisms by which NO influences plant responses to various stimuli. Additionally, growing evidence suggests that NO signalling interacts with the salicylic acid and jasmonic acid signalling pathways

Nitric oxide : Comparative synthesis and signaling in animal and plant cells.

55 ref.International audienc

Benzothiadiazole, an inducer of plant defenses, inhibits catalase and ascorbate peroxidase

International audienc

NO synthesis and signaling in plant: Where do we stand?

Over the past 20 years, nitric oxide (NO) research has generated a lot of interest in various aspects of plant biology. It is now clear that NO plays a role in a wide range of physiological processes in plants. However, in spite of the significant progress that has been made in understanding NO biosynthesis and signaling in planta, several crucial questions remain unanswered. Here we highlight several challenges in NO plant research by summarizing the latest knowledge of NO synthesis and by focusing on the potential NO source(s) and players involved. Our goal is also to provide an overview of how our understanding of NO signaling has been enhanced by the identification of array of genes and proteins regulated by NO

Silencing of the mitogen-activated protein kinase MPK6 compromises disease resistance in Arabidopsis

Here, we use a loss-of-function approach to demonstrate that the Arabidopsis (Arabidopsis thaliana) mitogen-activated protein kinase (MAPK) MPK6 plays a role in resistance to certain pathogens. MPK6-silenced Arabidopsis showed no apparent morphological phenotype or reduced fertility, indicating MPK6 is not required for development. However, resistances to an avirulent strain of Peronospora parasitica and avirulent and virulent strains of Pseudomonas syringae were compromised, suggesting that MPK6 plays a role in both resistance gene–mediated and basal resistance. Furthermore, this result demonstrates that MPK6's function cannot be fully complemented by other endogenous MAPKs. Although MPK6-silenced plants exhibited enhanced disease susceptibility, their ability to develop systemic acquired resistance or induced systemic resistance was unaffected. Expression of the pathogen-inducible gene VEGETATIVE STORAGE PROTEIN1 (VSP1) in MPK6-silenced plants was severalfold lower than in control plants, but the expression of other defense genes was comparable to the level observed in control plants. Taken together, these results provide direct evidence that a specific MAPK positively regulates VSP1 expression and resistance to a primary infection by certain pathogens, whereas systemic resistance and expression of several other defense genes appears to be mediated either by a functionally redundant MAPK(s) or independently from MPK6-dependent resistance

Nitric oxide modulates the activity of tobacco aconitase

60 ref.International audienc

Nitric Oxide Modulates the Activity of Tobacco Aconitase.

60 ref.International audienc

Silencing of the mitogen-activated protein kinase MPK6 compromises disease resistance in Arabidopsis

Here, we use a loss-of-function approach to demonstrate that the Arabidopsis (Arabidopsis thaliana) mitogen-activated protein kinase (MAPK) MPK6 plays a role in resistance to certain pathogens. MPK6-silenced Arabidopsis showed no apparent morphological phenotype or reduced fertility, indicating MPK6 is not required for development. However, resistances to an avirulent strain of Peronospora parasitica and avirulent and virulent strains of Pseudomonas syringae were compromised, suggesting that MPK6 plays a role in both resistance gene–mediated and basal resistance. Furthermore, this result demonstrates that MPK6's function cannot be fully complemented by other endogenous MAPKs. Although MPK6-silenced plants exhibited enhanced disease susceptibility, their ability to develop systemic acquired resistance or induced systemic resistance was unaffected. Expression of the pathogen-inducible gene VEGETATIVE STORAGE PROTEIN1 (VSP1) in MPK6-silenced plants was severalfold lower than in control plants, but the expression of other defense genes was comparable to the level observed in control plants. Taken together, these results provide direct evidence that a specific MAPK positively regulates VSP1 expression and resistance to a primary infection by certain pathogens, whereas systemic resistance and expression of several other defense genes appears to be mediated either by a functionally redundant MAPK(s) or independently from MPK6-dependent resistance