Salicylic acid has a role in regulating gene expression during leaf senescence.
Leaf senescence is a complex process that is controlled by multiple developmental and environmental signals and is manifested by induced expression of a large number of different genes. In this paper we describe experiments that show, for the first time, that the salicylic acid (SA)-signalling pathway has a role in the control of gene expression during developmental senescence. Arabidopsis plants defective in the SA-signalling pathway (npr1 and pad4 mutants and NahG transgenic plants) were used to investigate senescence-enhanced gene expression, and a number of genes showed altered expression patterns. Senescence-induced expression of the cysteine protease gene SAG12, for example, was conditional on the presence of SA, together with another unidentified senescence-specific factor. Changes in gene expression patterns were accompanied by a delayed yellowing and reduced necrosis in the mutant plants defective in SA-signalling, suggesting a role for SA in the cell death that occurs at the final stage of senescence. We propose the presence of a minimum of three senescence-enhanced signalling factors in senescing leaves, one of which is SA. We also suggest that a combination of signalling factors is required for the optimum expression of many genes during senescence.
Morris
K
K
Department of Plant Genetics and Biotechnology, Horticulture Research International, Wellesbourne, Warwick CV35 9EF, UK.
MacKerness
S A
SA
Page
T
T
John
C F
CF
Murphy
A M
AM
Carr
J P
JP
Buchanan-Wollaston
V
V
D017360:Arabidopsis / Q000235:genetics / Q000502:physiology; D015152:Blotting, Northern; D018506:Gene Expression Regulation, Plant; D009154:Mutation; D018515:Plant Leaves / Q000502:physiology*; D020156:Salicylic Acid / Q000378:metabolism*; D015398:Signal Transduction
D020156:Salicylic Acid