Ethylene synthesis regulated by biphasic induction of 1-aminocyclopropane-1-carboxylic acid synthase and 1-aminocyclopropane-1-carboxylic acid oxidase genes is required for hydrogen peroxide accumulation and cell death in ozone-exposed tomato.
We show that above a certain threshold concentration, ozone leads to leaf injury in tomato (Lycopersicon esculentum). Ozone-induced leaf damage was preceded by a rapid increase in 1-aminocyclopropane-1-carboxylic acid (ACC) synthase activity, ACC content, and ethylene emission. Changes in mRNA levels of specific ACC synthase, ACC oxidase, and ethylene receptor genes occurred within 1 to 5 h. Expression of the genes encoding components of ethylene biosynthesis and perception, and biochemistry of ethylene synthesis suggested that ozone-induced ethylene synthesis in tomato is under biphasic control. In transgenic plants containing an LE-ACO1 promoter-beta-glucuronidase fusion construct, beta-glucuronidase activity increased rapidly at the beginning of the O(3) exposure and had a spatial distribution resembling the pattern of extracellular H(2)O(2) production at 7 h, which coincided with the cell death pattern after 24 h. Ethylene synthesis and perception were required for active H(2)O(2) production and cell death resulting in visible tissue damage. The results demonstrate a selective ozone response of ethylene biosynthetic genes and suggest a role for ethylene, in combination with the burst of H(2)O(2) production, in regulating the spread of cell death.
Moeder
Wolfgang
W
Institute of Biochemical Plant Pathology, GSF-National Research Center for Environemtn and Health, Oberschleissheim, Germany.
Barry
Cornelius S
CS
Tauriainen
Airi A
AA
Betz
Christian
C
Tuomainen
Jaana
J
Utriainen
Merja
M
Grierson
Donald
D
Sandermann
Heinrich
H
Langebartels
Christian
C
Kangasjärvi
Jaakko
J
D000594:Amino Acid Oxidoreductases / Q000096:biosynthesis / Q000235:genetics*; D017209:Apoptosis / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D004790:Enzyme Induction / Q000187:drug effects; D005030:Ethylenes / Q000096:biosynthesis*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D005966:Glucuronidase / Q000235:genetics / Q000378:metabolism; D006861:Hydrogen Peroxide / Q000378:metabolism*; D008190:Lyases / Q000096:biosynthesis / Q000235:genetics*; D018551:Solanum lycopersicum / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D010126:Ozone / Q000494:pharmacology*; D030821:Plants, Genetically Modified; D017382:Reactive Oxygen Species / Q000378:metabolism; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism
D005030:Ethylenes; D017382:Reactive Oxygen Species; D011993:Recombinant Fusion Proteins; D010126:Ozone; C036216:ethylene; D006861:Hydrogen Peroxide; D000594:Amino Acid Oxidoreductases; C059460:1-aminocyclopropane-1-carboxylic acid oxidase; D005966:Glucuronidase; D008190:Lyases; C021773:1-aminocyclopropanecarboxylate synthase