title: Optimizing micropropagation of drought resistantPyrus boissierianaBuhse.
abstract: The present study concentrated on introducing a micropropagation protocol for a drought resistant genotype fromPyrus boissieriana, which is the second most naturally widespread pear species in Iran with proper physiological and medicinal properties. Proliferating microshoot cultures were obtained by placing nodal segments on MS medium supplemented with BAP and IBA or NAA. The highest number of shoots (27 shoots per explant) were obtained with 1.5 mg l-1BAP and 0.05 mg l-1IBA, but this combination did not produce shoots of desirable length (>1.7 cm). Combination of 1.75 mg l-1BAP and 0.07 mg l-1IBA was the best for the shoot multiplication inP. boissierianawith a sufficient number of shoot production (22.33 shoots per explant) and relatively more appropriate shoot length. The larger and greenish leaves were obtained when PG was added to the best multiplication treatment. Microshoot elongation was carried out in 1/2 and 1/4 MS medium containing 50-100 mg l-1PG with different concentrations of IBA or NAA at intervals of 30-60 days. Significant increase in shoot length was detected after 45-60 days of culture in the presence of PG. The highest shoot length (8 cm) was recorded on 1/2 MS medium supplemented with 0.5 mg l-1IBA and 100 mg l-1PG. GA3negatively affected number and length of shoots and generally caused generation of red leaves. The highest percentage of root induction (100%) and root length (9 cm) were obtained on 1/6 strength MS medium supplemented with 0.005 mg l-1IBA. All plantlets were hardened when transferred to ex vitro conditions through a period of 25-30 days. The results suggest axillary shoot proliferation ofP. boissierianacould successfully be employed for propagation of candidate drought resistant seedling.
authors.affiliation: Department of Biotechnology, Faculty of New Technologies and Energy Engineering, Shahid Beheshti University, G. C., Tehran, Iran.
authors.forename: Maryam
authors.initials: M
authors.lastname: Zakavi
authors.affiliation: Department of Biotechnology, Faculty of New Technologies and Energy Engineering, Shahid Beheshti University, G. C., Tehran, Iran.
authors.forename: Hossein
authors.initials: H
authors.lastname: Askari
authors.affiliation: Department of Biotechnology, Faculty of New Technologies and Energy Engineering, Shahid Beheshti University, G. C., Tehran, Iran.
authors.forename: Neda
authors.initials: N
authors.lastname: Irvani
keywords: Micropropagation; Plant growth regulators; Pyrus boissieriana Buhse; Root induction; Shoot elongation