Characteristics evaluation of transgenic delay-flowering pineapple (Ananas comosus L. Merr.)

Pineapple (Ananas comosus) is an important economic crop in Taiwan; however, shortening day length and low temperature in winter promote endogenous ethylene production which leads to natural flowering. A key enzyme involved in ethylene biosynthesis, 1-aminocyclopropane 1-carboxylate deaminase deaminase (ACCD), was cloned and introduced into popular pineapple cultivar 'Tainon 17' through particle bombardment method. Materials of the transgenic pineapple were kindly provided by Prof. Chin-Ho Lin of National Chung Hsing University. Two copies of ACCD transgene were detected in the transgenic 'Tainon 17' genome by southern blot analysis. In vitro seedling wound assay showed that ethylene production by the ACCD transgenic line was significantly lower than non-transgenic 'Tainon 17' for the first week. Furthermore, significantly lower ethylene concentrations were detected both in vegetative and in reproductive periods of ACCD transgenic line when compared with 'Tainon 17'. Flowering characteristics of ACCD transgenic line were investigated in-field in central Taiwan for two years. Flowering time records revealed obviously delay-flowering characteristics for ACCD pineapple compared with 'Tainon 17'. The present study demonstrates that introducing a foreign gene, ACCD, into pineapple apparently altered the flowering nature.