Germination of synthetic seeds of pineapple (Ananas comosus L. Merr.]

Tufts of multiple shoots were produced from dormant, axillary buds of pineapple in vitro. Tiny shoots (2-5 mm) isolated from the tuft of multiple shoots were encapsulated in 3% sodium alginate prepared using hormone-free Murashige and Skoog's basal medium, Murashige and Skoog's vitamins, 0.56 mM myo-inositol and 0.06 M sucrose. The encapsulated shoots represented synthetic seeds that germinated and formed roots in vitro after subculture onto one of the following media solidified with 0.8% agar: (1) hormone-free Murashige and Skoog's basal medium, Murashige and Skoog's vitamins, 0.56 mM myo-inositol and 0.06 M sucrose (Pin 1), (2) Murashige and Skoog's basal medium, Murashige and Skoog's vitamins, 0.56 mM myo-inositol, 0.06 M sucrose, 9.67 muM 1-naphthalene acetic acid, 9.84 muM indole-3-butyric acid and 9.29 muM kinetin (Pin2), and (3) White's basal medium, White's vitamins, 0.56 mM myoinositol, 0.03 M sucrose, 0.54 muM 1-naphthalene acetic acid and 1.97 muM indole-3-butyric acid (Pin3). Pretreatment of shoots in either liquid Pin3 or Pin4 medium (White's basal medium, White's vitamins, 0.56 mM myoinositol, 0.03 M sucrose, 10.8 muM 1-naphthalene acetic acid and 39.4 muM indole-3-butryic acid) was required for development into plantlets with roots after culture on either Pin1, Pint or Pin3 media. One hundred percent germination of synthetic seeds to plantlets occurred after pretreatment of shoots in liquid Pin4 medium for 12 h followed by culture of synthetic seeds on Pint medium. Synthetic seeds stored at 4degreesC remained viable without sprouting for up to 45 days. Plantlets produced in vitro from synthetic seeds were successfully established in soil. The protocol provides an easy and novel propagation system for pineapple, an otherwise vegetatively propagated fruit crop.