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Title: HIGH FREQUENCY PLANTLET REGENERATION FROM LEAF AND PETIOLE EXPLANTS OF COMMERCIAL PEAR (PYRUS COMMUNIS L.) CULTIVARS 'ONWARD' AND 'OLD HOME'

Author
item SUN, QINGRONG - TAIAN SHANDONG CHINA
item SUN, HONGYAN - TAIAN SHANDONG CHINA
item Hammond, Rosemarie
item Davis, Robert
item Zhao, Yan

Submitted to: Plant Cell Reports
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/1/2006
Publication Date: 8/1/2006
Citation: Sun, Q., Sun, H., Hammond, R., Davis, R.E., Zhao, Y. 2006. High frequency plantlet regeneration from leaf and petiole explants of commercial pear (pyrus communis l.) cultivars 'onward' and 'old home'. Plant Cell Reports.

Interpretive Summary: Being high in fiber, low in calories, and rich in vitamins and minerals, pear is a nutrient-dense fruit with strong consumer demand. However, pear production has often been threatened by diseases caused by bacteria, fungi and viruses. Because pear possesses a highly variable genetic background and takes five to six years to flower, conventional breeding for disease resistance is very difficult and time-consuming. Artificially engineered resistance is a new strategy for plant disease control. This involves introduction of foreign genes into parent tissues and subsequent regeneration of transgenic plants with desired characters. An important prerequisite for successful implementation of such genetic manipulation is establishment of an efficient regeneration protocol so that genetically altered plants can be grown back from individual cells. In the present study, we examined the major factors that affect plant regeneration from cells of parent leaf tissues of two commercial pear cultivars, ‘Onward’ and ‘Old Home’. Optimal conditions, including the composition of culture medium and growth regulators, were established for high-frequency plantlet regeneration required to carry out genetic engineering of the pear cultivars. The findings will be of greatest interest to research scientists and professionals in plant biotechnology.

Technical Abstract: Major parameters affecting adventitious shoot formation from in vitro explants of two commercial pear cultivars, ‘Onward’ and ‘Old Home’, were examined. Optimal conditions were established for high-frequency plantlet regeneration needed to carry out genetic transformation of the pear cultivars. The regeneration frequency of cultivar ‘Onward’ reached 90% on NN69 medium containing 4 mg/L thidiazuron (TDZ) and 0.7 mg/L indole 3-butyric acid (IBA). The regeneration frequency of cultivar ‘Old Home’ reached 100% when leaf explants were subjected to a two-phase culture regimen. In the shoot primordium induction phase, leaf segments were cultured on NN69 medium supplemented with 4 mg/L TDZ and 0.3 mg/L alpha-naphthalene acetic acid (NAA); in the subsequent shoot elongation phase, emerging shoots were cultivated on MS medium supplemented with 0.3 mg/L 6-benzylaminopurine (6-BA) and 0.1 mg/L IBA. While shoot regeneration from ‘Onward’ explants occurred via direct organogenesis, regeneration from ‘Old Home’ explants followed an indirect organogenesis pathway.