Light‐dependent hypersensitive response and resistance signaling against Turnip Crinkle Virus in Arabidopsis

• Published in: The Plant journal : for cell and molecular biology 2006-02, Vol.45 (3), p.320-334
• Main Authors: Chandra‐Shekara, A. C., Gupte, Manisha, Navarre, Duroy, Raina, Surabhi, Raina, Ramesh, Klessig, Daniel, Kachroo, Pradeep
• Format: Article
• Language: English
• Subjects: Agronomy. Soil science and plant productions; Arabidopsis; Arabidopsis - genetics; Arabidopsis - metabolism; Arabidopsis - virology; Arabidopsis Proteins - genetics; Arabidopsis Proteins - metabolism; Arabidopsis Proteins - physiology; Biological and medical sciences; Botany; Carmovirus - pathogenicity; defense; DNA-Binding Proteins - genetics; DNA-Binding Proteins - metabolism; Fundamental and applied biological sciences. Psychology; Gene Expression Profiling; Gene Expression Regulation, Plant; Genes; Genetics and breeding of economic plants; Immunity, Innate; Light; Models, Biological; Pest resistance; Phenotype; Phytochrome A - physiology; Phytochrome B - physiology; Plant Leaves - anatomy & histology; Plant Leaves - metabolism; Plant Leaves - virology; Plant pathogens; Plant pathology; Plants, Genetically Modified - drug effects; Plants, Genetically Modified - metabolism; Plants, Genetically Modified - virology; Repressor Proteins - genetics; Repressor Proteins - metabolism; salicylic acid; Salicylic Acid - metabolism; Salicylic Acid - pharmacology; Signal Transduction; signaling; ssi2; Tobacco mosaic virus; Tobacco Mosaic Virus - pathogenicity; Turnip Crinkle Virus; Up-Regulation; Varietal selection. Specialized plant breeding, plant breeding aims; Viruses
• ISSN: 0960-7412; 1365-313X
• DOI: 10.1111/j.1365-313X.2005.02618.x

Summary Resistance to Turnip Crinkle Virus (TCV) in Arabidopsis ecotype Dijon (Di)‐17 is conferred by the resistance gene HRT and a recessive locus rrt. In Di‐17, TCV elicits a hypersensitive response (HR), which is accompanied by increased expression of pathogenesis‐related (PR) genes and high levels of salicylic acid (SA). We have previously shown that HRT‐mediated resistance to TCV is dependent on SA‐mediated signal transduction and that increased levels of SA confer enhanced resistance to TCV via upregulation of the HRT gene. Here we show that HRT‐mediated HR and resistance are dependent on light. A dark treatment immediately following TCV inoculation suppressed HR, resistance and activation of the majority of the TCV‐induced genes. However, the absence of light did not affect either TCV‐induced elevated levels of free SA or the expression of HRT. Interestingly, in the dark, transgenic plants overexpressing HRT showed susceptibility, but overexpression of HRT coupled with high levels of endogenous SA resulted in pronounced resistance. Consistent with these results is the finding that exogenous application of SA prior to TCV inoculation partially overcame the requirement for light. Light was also required for N gene‐mediated HR and resistance to Tobacco Mosaic Virus, suggesting that it is an important factor which may be generally required during defense signaling.