Cryptogein-induced transcriptional reprogramming in tobacco is light dependent.

The fungal elicitor cryptogein triggers a light-dependent hypersensitive response in tobacco (Nicotiana tabacum). To assess the effect of light on this nonhost resistance in more detail, we studied various aspects of the response under dark and light conditions using the tobacco-cryptogein experimental system. Here, we show that light drastically alters the plant's transcriptional response to cryptogein, notably by dampening the induction of genes involved in multiple processes, such as ethylene biosynthesis, secondary metabolism, and glutathione turnover.

Extranuclear protection of chromosomal DNA from oxidative stress.

Eukaryotic organisms evolved under aerobic conditions subjecting nuclear DNA to damage provoked by reactive oxygen species (ROS). Although ROS are thought to be a major cause of DNA damage, little is known about the molecular mechanisms protecting nuclear DNA from oxidative stress. Here we show that protection of nuclear DNA in plants requires a coordinated function of ROS-scavenging pathways residing in the cytosol and peroxisomes, demonstrating that nuclear ROS scavengers such as peroxiredoxin and glutathione are insufficient to safeguard DNA integrity.

Nitric oxide- and hydrogen peroxide-responsive gene regulation during cell death induction in tobacco.

Nitric oxide (NO) and hydrogen peroxide (H(2)O(2)) are regulatory molecules in various developmental processes and stress responses. Tobacco (Nicotiana tabacum) leaves exposed to moderate high light dramatically potentiated NO-mediated cell death in catalase-deficient (CAT1AS) but not in wild-type plants, providing genetic evidence for a partnership between NO and H(2)O(2) during the induction of programmed cell death. With this experimental model system, the specific impact on gene expression was characterized by either NO or H(2)O(2) alone or both molecules combined.

A comprehensive analysis of hydrogen peroxide-induced gene expression in tobacco.

Hydrogen peroxide plays a central role in launching the defense response during stress in plants. To establish a molecular profile provoked by a sustained increase in hydrogen peroxide levels, catalase-deficient tobacco plants (CAT1AS) were exposed to high light (HL) intensities over a detailed time course. The expression kinetics of >14000 genes were monitored by using transcript profiling technology based on cDNA-amplified fragment length polymorphism.