soluble form of polyvinylpyrrolidone to trap phenolics prevented the polyphenols present in the coffee fruit from adhering to the nucleic acid it was further discovered that the problems of carbohydrate and phenolic compound contamination of the precipitated mrna could be minimized by employing two precipitation steps instead of one i e a chloroform ethanol precipitation of the specially buffered homogenate selectively precipitated the phenolic compounds but not the rna the phenolic compounds were extracted into the organic phase and the rna and carbohydrates remained in the aqueous phase the aqueous phase was then subjected to an extraction with 3m sodium chloride and alcohol this extraction precipitated the rna exclusively suppression of synthesis of coffee fruit expressed acc synthase and or acc oxidase in transformed coffee plants the strategy for controlling ethylene biosynthesis in coffee plants according to the present invention relates in the first instance to determination of the genes that code on expression for two enzymes in the ethylene pathway during coffee fruit ripening acc synthase and acc oxidase transformation of wild type coffee plants with constructs containing either or both genes in an orientation that is antisense or sense to the normal genes is expected to block synthesis of the respective enzymes in general to produce an antisense rna transcript nucleic acid sequences derived from the gene or a naturally occurring allelic variant of the gene whose expression is to be reduced e g coffee fruit expressed acc synthase and or acc oxidase are placed downstream of a transcription promoter in the opposite transcriptional orientation relative to the direction of transcription of the endogenous gene present in the chromosome the resulting antisense construct is introduced into the plant cell host where the antisense.