|dc.description.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.
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