Effects of ethylene and ethylene inhibitors on white spruce somatic embryo maturation

Abstract

The influence of ethylene on somatic embryo maturation of white spruce (Picea glauca (Moench) Voss) was studied through applications of ethephon, silver nitrate (AgNO3), cobalt chloride (CoCl2) and aminoethoxyvinylglycine (AVG) in the presence or absence of abscisic acid (ABA). Ethylene was produced by the embryogenic tissue during embryo maturation. After an initial rise in ethylene production 1 day after transferring from the maintenance to maturation medium, the level of ethylene decreased and this was followed by a gradual rise in the latter half of the culture period. ABA, AgNO3, and CoCl2 were effective in suppressing ethylene production during the first 2 weeks in the maturation medium. AgNO3 and CoCl2 were effective to a lesser extent than ABA in promoting embryo production. AVG was effective in suppressing ethylene production through the entire culture period. However, when applied alone in the absence of ABA, AVG could not stimulate embryo formation. The presence of AVG or AgNO3 improved the quality of the embryo by preventing large intercellular space formation in the shoot pole of the somatic embryo. Ethephon inhibited embryo production and enhanced formation of the intercellular spaces. It is concluded that ethylene had a negative effect on white spruce somatic embryo development. An alternate role for AgNO3 is also discussed. © 1994.