In Vitro Vulture of the Passion Fruit, Passiflora Edulis Sims

Abstract

In Vitro Culture of the Passion Fruit. Passiflora edulis Sims In this study, a tissue culture method, which can be used for multiplication of the yellow passion fruit is described. Callus was Initiated from different explants of the yellow and purple passion fruit. Immature seeds of var. edulis formed callus when Inoculated on MS ( Murashlge and Skoog) medium containing 1 - 3 mg/1 a-napthaleneacetic acid ( NAA) and 0.5 mg/l 6-benzyiamlnopurlne (BAP). Stem explants of var. edulis and var. flavicaroa formed callus when Inoculated on MS media supplemented with 2 mg/1 NAA, with or without 0.5 mg/1 BAP. Stem segments with nodes formed shoots when Inoculated on MS medium with 2 mg/1 BAP or 2 mg/1 BAP and 0.2 mg/1 NAA. Leaf discs of var. flavlcarpa formed callus when inoculated on MS medium supplemented with 2 mg/1 NAA, 2 mg/1 indole-3-aceticacid ( IAA) and 0.4 mg/1 kinetin (K IN ). Those inoculated on medium with 2 mg/1 NAA or 2 mg/1 NAA and 0.5 mg/1 KIN formed callus and roots within 4 weeks. Shoots were observed on leaf discs of var. flavicaroa Inoculated on MS medium supplemented with 2 mg/1 BAP or 2 mg/1 BAP and 0.5 mg/1 KIN within 4 weeks. The shoots were then subcultured onto MS medium supplemented with 0.1 mg/1 BAP for further growth. Such shoots could be induced to root when subcultured onto MS media containing 0.1, 0.5 and 1 mg/1 NAA. Rooted plantlets could be obtained within 8 weeks. In this study, investigations were also carried out to determine whether passion fruit is a host for infection by Aarobacterium. Aorobacterium tuanefaciens is a Gram-negative soil bacterium that can cause the formation of tumours on certain wounded plants. This bacterium harbours an oncogenic Ti plasmid which enables it to induce crown gall tumours on most dicotyledonous and some monocotyledonous plants. The Ti plasmid has a segment, called the T-DNA, which is transferred from the bacterium and becomes stably Integrated into the plant genome. Hence, A. tumefaciens can be used as a vector to transfer foreign genes into plants. ix Results obtained showed that passion fru it is susceptible to Aorobacterium infection. Tumours were induced on the plant infected with the hypervirulent A. tumefaciens strain A 2 8 1. These tumours could grow on MS medium without hormones, free of the inciting bacteria. Agropine, a compound whose synthesis is directed by A. tumefaciens genes, could be detected in the tumor tissue. These findings open the possibility of improving passion fruit by genetic engineering. Experiments done to investigate the problem of seed dormancy in passion fruit confirmed that the tough seed coat could be the major cause. It was established that dormancy could be broken by scarification and subsequent treatment of the scarified seeds with gibberellic acid.