SHOOT ORGANOGENESIS FROM LEAF EXPLANTS IN JAPANESE PEAR (PYRUS PYRIFOLIA)

Abstract

The effect of benzyladenine (BA) and thidiazuron (TDZ) in combination with -naphthaleneacetic acid and indole-3-butyric acid (IBA) on in vitro shoot regeneration from leaf segments of several Japanese pears was investigated. A regeneration protocol was developed and regeneration was achieved from six cultivars: – ‘Kosui’, ‘Hosui’, ‘Niitaka’, ‘Wasekaso’, ‘Okusankichi’ and ‘Whangkeumbae’ pears. The highest regeneration rate was obtained in most shoots from young leaves on a medium based on MS macroelements supplemented with 0.1-1.0 mg/L TDZ and 0.1-1.0 mg/L IBA and/or NAA in each cultivar. Physiological differences with BA and TDZ treatments were compared. In the regeneration medium with BA treatments, green foci appeared on the callus surface after 8 days. Then, some adventitious buds were induced on those green foci, resulting in normal shoots. On the other hand, in the medium with TDZ, callus surface turned compact and greenish, and many adventitious buds were formed over the whole area of the callus surface. In some shoots, cultured on the medium with TDZ, there were morphologically abnormal shoots, including vitrified shoots. A-fourth strength MS medium supplemented with 0.1 mg/L NAA produced plantlets in good quality of root number and root length.