Optimization of hairy roots induction in purslane (Portulaca oleracea L.) by Agrobacterium Rhizogenes

Common purslane (Portulaca oleracea L.), is a member of the Portulacaceae, which consists of more than 120 species of often succulent herbs and shrubs. It has been used as a folk medicine in many countries as a diuretic, febrifuge, antiseptic, antispasmodic and vermifuge. Hairy roots are adventitious roots derived from cells transformed by the root-inducing plasmid Ri of Agrobacterium Rhizogenes, and they grow in the absence of phytohormones. The hairy root harbors the T-DNA segment of plasmid Ri within its nuclear genomes. In this research four different explant (leaf, stem, Cotyledon, hypocotyl) in three different ages were used for infected by ATCC11325 strain of A. Rhizogenes that grown on 25 ml Liquid LB medium containing 50 mg/l of antibiotic rifampicin. The frequencies of hairy root induction for different types of explants were considerably different. Among the different explants that were tested, maximum transformation frequency was documented in 30-day-old leaf explants (80%) whereas the minimum transformation frequency (30%) was recorded in 30-days-old stem which was comparatively lower than other explants. Maximum number of roots (4.6 roots per explant) and maximum length of root (3.3 cm) were induced from 30-day-old leaf explants. The results of this research show that induction of hairy roots in purslane by A. rhizogenes is possible with high efficiency and these results may be useful in genetic manipulation of P. oleracea L. and use of hairy root culture to produce high-value secondary metabolites.

Keywords:

Agrobacterium rhizogenes , Hairy roots , rolB gene , Secondary metabolites.