Presentation on theme: "ETHYLENE BIOSYNTHESIS Jean-Claude PECH. ETHYLENE ORIGINATING FROM LIPIDS? Until 1964, ethylene was though to derive from the enzymatic disruption of lipids."— Presentation transcript:
ETHYLENE BIOSYNTHESIS Jean-Claude PECH
ETHYLENE ORIGINATING FROM LIPIDS? Until 1964, ethylene was though to derive from the enzymatic disruption of lipids involving free radicals formation Arguments: -Oxygen is required for the biosynthesis of ethylene in plants; -Free radical scavengers (antioxidants that prevent lipid oxidation, e.g. propyl gallate...) inhibited ethylene production.
DISCOVERY OF METHIONINE AS A PRECURSOR OF ETHYLENE Lieberman and Mapson, 1964 * Methionine NH 3 + CH 3 -S-CH 2 -CH 2 -CH-COO-
OTHER INHIBITORS OF ETHYLENE SYNTHESIS Lieberman and Owens, 1971 CH2-CH-CH2-O-C=C-CH-COOH OH NH2 H NH2 H Rhizobitoxine from Rhizobium japonicum CH2-CH2-CH2-O-C=C-CH-COOH NH2 H NH2 H AVG= Amino ethoxy vinyl glycine from Streptomyces
Shang-Fa YANG DISCOVERY OF ACC AND METHIONINE CYCLE « Knight of Roquetaillade », Ethylene Congress Agen, 1992
Radio-chromatograms of ethylene extracts of apple plugs 14 C-Methionine Plugs in air, 12h Plugs in N2, 6h then in air, 6h
At-ACS1 (induced by cycloheximide) At-ACS5 [induced by Li, cycloheximide(CH) and low concentration of cytokinin(CK)] At-ACS4 (induced by CH, IAA and wounding) At-ACS2 (induced by Li, CH, wounding) At-ACS4 induced by CH, IAA, wounding) At-ACS4 (induced by CH, IAA, anaerobisis and wounding) Adult plantEtiolated seedling At-ACS5 (basal level stimulated by Li and CK At-ACS8 not yet characterized At-ACS10 in response to light in plants over expressing CONSTANS At-ACS2 in young leaves and flowers At-ACS7 (induced by CH) At-ACS9 = eto1 At-ACS6 (induced by O 3, Cu 2+, IAA, CH, CN -, anaerobiosis, wounding, touching and ethylene) At-ACS1 At-ACS2 Le-ACS2 Le-ACS4 At-ACS6 Le-ACS6 Le-ACS1A Le-ACS1B At-ACS7 At-ACS11 Le-ACS5 At-ACS4 At-ACS8 At-ACS5 At-ACS9 Le-ACS7 Le-ACS3 Le-ACS8 At-ACS10 At-ACS12 Branch I Branch II Branch III * * * * * ACC SYNTHASE GENE FAMILY IN ARABIDOPSIS
Le-ACO1, 3 Le-ACO1 in senescent or wounded leaves Le- ACO2 Le-ACO1,2,3 and 4 induced by O 3 Le-ACO3 (breaker stage) Le-ACO4 Le-ACS7 induced early by wounding Le-ACS6 (in MG fruit) negativ. regul. by ethylene Le-ACS4 induced by wounding Le-ACS1A (breaker stage) negativ. regul. by ethylene FLOWER Le-ACS7 induced early by flooding Le-ACS3 induced by flooding Le-ACS2 and 4 positiv. regul. by ethylene Le-ACS3 (not expressed in fruit, present in tomato cell suspension) Le-ACS2 (stamens, mature and senescent anthers) Le-ACS2 (senescent petals) ACO AND ACS GENE EXPRESSION IN TOMATO
Regulation of ethylene biosynthetic genes ACC synthase ArabidopsisRapidly induced by auxin (ACS4). Induced by low levels of cytokinin (ACS5). RumexFlood resistant species downregulates ACS, flood sensitive does not. RiceEnzyme activity induced by hypoxia/flooding. Mung beanInduced by mechanical stress (AIM1). TomatoInduced by fruit ripening. Induced by flooding (ACS3). Induced by ozone (ACS2). PhaseolusInduced by auxin (ACS1). Synergistic induction with auxin (ACS2). Winter squashInduced by auxin (accA). Induced by wounding (accW). PhalaenopsisInduced by ethylene (ACS1) Induced in stigma after pollination or auxin treatment (ACS1, ACS2). Induced in ovary after pollination or auxin treatment (ACS3). CarnationLate induction by ethylene, pollination induces expression after hours in petals (CARACC3). StellariaRegulated by photoperiod. PotatoRapidly induced by ozone, infection and Cu2+ (ACS5). Slowly induced by ozone, infection and Cu2+ (ACS4). ZucchiniInduced by wounding and auxin only in fruit (ACC1A). ACC oxidase ArabidopsisInduced by ethylene (ACO2/E1305). TomatoACO1 antisense transgenic plants have reduced ethylene production and epinasty after flooding. Induced during flower development (ACO1-3). Induced by wounding (ACO1). Induced during senescence (ACO, ACO3). PhalaenopsisInduced by ethylene. Unpollinated flowers cannot convert ACC to ethylene. CantaloupeInduced by ethylene, wounding, NaCl, drought and ripening (ACO1). Induced by NaCl and drought (ACO3). PetuniaInduced by ethylene (ACO3). Induced in senescing floral organs (ACO1, ACO3). Induced in developing pistils (ACO3, ACO4). Winter SquashInduced by wounding, induction blocked by ethylene inhibitor, endogenous ethylene accelerates induction. CarnationInduced by pollination in styles and petals (SR120). Mung beanInduced by ethylene(ACO1, ACO2). PeachInduced by wounding and fruit ripening. AppleInduced during fruit ripening. BroccoliInduced after harvest (ACC Ox1). Induced in reproductive organs postharvest (ACC Ox2).