Premium
Expression of a nitric oxide degrading enzyme induces a senescence programme in Arabidopsis
Author(s) -
MISHINA TATIANA E.,
LAMB CHRIS,
ZEIER JÜRGEN
Publication year - 2007
Publication title -
plant, cell and environment
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.646
H-Index - 200
eISSN - 1365-3040
pISSN - 0140-7791
DOI - 10.1111/j.1365-3040.2006.01604.x
Subject(s) - senescence , arabidopsis , biology , arabidopsis thaliana , microbiology and biotechnology , cytokinin , nitric oxide , gene expression , biochemistry , gene , auxin , mutant , endocrinology
Nitric oxide (NO) has been proposed to act as a factor delaying leaf senescence and fruit maturation in plants. Here we show that expression of a NO degrading dioxygenase (NOD) in Arabidopsis thaliana initiates a senescence‐like phenotype, an effect that proved to be more pronounced in older than in younger leaves. This senescence phenotype was preceded by a massive switch in gene expression in which photosynthetic genes were down‐regulated, whereas many senescence‐associated genes (SAGs) and the 1‐aminocyclopropane‐1‐carboxylic acid (ACC) synthase gene ACS6 involved in ethylene synthesis were up‐regulated. External fumigation of NOD plants with NO as well as environmental conditions known to stimulate endogenous NO production attenuated the induced senescence programme. For instance, both high light conditions and nitrate feeding reduced the senescence phenotype and attenuated the down‐regulation of photosynthetic genes as well as the up‐regulation of SAGs. Treatment of plants with the cytokinin 6‐benzylaminopurin (BAP) reduced the down‐regulation of photosynthesis, although it had no consistent effect on SAG expression. Metabolic changes during NOD‐induced senescence comprehended increases in salicylic acid (SA) levels, accumulation of the phytoalexin camalexin and elevation of leaf γ ‐tocopherol contents, all of which occurred during natural senescence in Arabidopsis leaves as well. Moreover, NO fumigation delayed the senescence process induced by darkening individual Arabidopsis Columbia‐0 (Col‐0) leaves. Our data thus support the notion that NO acts as a negative regulator of leaf senescence.