Field evaluation of transgenic pineapple (Ananas comosus (L.) Merr.) cv. ‘Smooth Cayenne’ for resistance to blackheart under subtropical conditions

• First report of field evaluation of pineapples genetically engineered for blackheart resistance
• Results validate use of transgenic technology to down-regulate expression of PPO and hence prevent blackheart expression in the fruit
• Blackheart resistant plants were produced irrespective of the transformation system used or the constructs deployed
• The transgenic approach, like conventional breeding, requires selection over several cycles

A comparative analysis of transgenic pineapple lines transformed with a polyphenol oxidase (PPO) gene (ppo) and the untransformed cultivar ‘Smooth Cayenne’ was made from plants grown in a series of field trials under cool subtropical conditions in southeast Queensland. In the four field trials where blackheart was recorded, all of the control lines expressed blackheart on each occasion and exhibited the greatest incidence (50%) and severity (34%) of symptoms. Irrespective of the gene transfer method or the gene construct used, 38% of the lines produced were regarded as blackheart resistant, having no blackheart symptoms in two or more trials. Five blackheart resistant transgenic lines consistently performed as well as or better than control plants in terms of fruit characteristics and quality.