Phytochrome signalling modulates the SA-perceptive pathway in Arabidopsis
Article first published online: 1 JUL 2002
The Plant Journal
Volume 31, Issue 1, pages 87–95, July 2002
How to Cite
Genoud, T., Buchala, A. J., Chua, N.-H. and Métraux, J.-P. (2002), Phytochrome signalling modulates the SA-perceptive pathway in Arabidopsis. The Plant Journal, 31: 87–95. doi: 10.1046/j.1365-313X.2002.01338.x
- Issue published online: 1 JUL 2002
- Article first published online: 1 JUL 2002
- Received 20 February 2002; revised 19 March 2002; accepted 22 March 2002.
- salicylic acid;
The interaction of phytochrome signalling with the SA signal transduction pathway has been investigated in Arabidopsis using single and multiple mutants affected in light perception (phyA and phyB deficient) and light-signal processing (psi2, phytochrome signalling). The induction of PR1 by SA and functional analogues has been found to strictly correlate with the activity of the signalling pathway controlled by both phyA and phyB photoreceptors. In darkness as well as dim light, and independently of a carbohydrate source, SA-induced PR gene expression as well as the hypersensitive response to pathogens (HR) are strongly reduced. Moreover, the initiation of HR also exhibits a strict dependence upon both the presence and the amplitude of a phytochrome-elicited signal. The growth of an incompatible strain of bacterial a pathogen (Pseudomonas syringae pv. tomato) was enhanced in phyA-phyB and decreased in psi2 mutants. While functional chloroplasts were found necessary for the development of an HR, the induction of PRs was strictly dependent on light, but independent of functional chloroplasts. Taken together, these data demonstrate that the light-induced signalling pathway interacts with the pathogen/SA-mediated signal transduction route. These results are summarized in a formalism that allows qualitative computer simulation.