Treated induced ethylene production

An important characteristic of ACC synthase in plant tissues is its lability. It has been well recognized that when ethylene production in plant tissues is induced by lAA treatment or by various stresses [33], ethylene production declines rapidly following induction, and this decline is accompanied by a corresponding decline in ACC content. Two mechanisms are responsible for this rapid decline in ethylene production one is the conjugation of ACC into MACC catalyzed by ACC malonyltransferase resulting in a reduced ACC level in the tissue, and the other is the inactivation of ACC synthase. The apparent half-life of ACC synthase in wounded green tomato pericarp and in lAA-treated mungbean hypocotyls has been estimated to be 30-50 min, based on the decay kinetics of the enzyme activity extracted from induced tissues in the presence of cycloheximide which blocks the new synthesis of the enzyme [1, 36]. 

Pre-treatment of apples with high CO2 can induce respiration and ethylene production at 20 °C storage, in addition to induction of other volatiles. These CO2" treated apples were rated by panelists as better flavoured than control fruit, with the 24-h-treated fruit being the most acceptable after 2 weeks at 20 °C (Pesis et al. 1994). 

Methane-ethylene mixtures react over sulphate-treated zirconia catalysts to yield higher hydrocarbons. Initially, C products predominate but with increasing time on stream lighter products are preferentially formed. There is a concomitant decline in overall catalytic activity. With ethylene alone, a different pattern of behaviour is found and it appears that the methane in the methane-ethylene mixture exerts a decided effect on the course of the reaction. Sulphate-treated zirconia undergoes thermally induced recrystallization in a different manner from that displayed by sulphate-free zirconia. 

Though these two products cannot be interconverted (i.e. no evidence of ethylene insertion or elimination), an over-pressure of CO does induce migratory insertion for 438 yielding Tp Rh C( = 0)Et (C6H5)(C0) (439), which reductively eliminates PhC( = 0)Et when treated with ZnBr2. 

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