Evaluation of in-vitro grown apple shoot sensitivity to Venturia inaequalis using a detached leaf assay

Silfverberg-Dilworth E., Patocchi A. and Gessler C.

IOBC/WPRS Bulletin 29 (1): 67-74, 2006

Assessment of scab susceptibility or resistance of apple plantlets, grown in-vitro, is important for early assessment of individuals transformed with putative scab resistance genes. Useful clones can be selected and only these plants need be grown further and acclimatised to the greenhouse. Here we describe a detached leaf assay carried out using in-vitro grown shoots of the cultivars Florina, Enterprise and Gala. We define resistance reaction classes observed on a microscopical level that enable us to distinguish resistant (Vf) cultivars from susceptible ones. Under the conditions described statisttically significant differences are seen between Florina (Vf) and Gala. Also tested are Florina shoots that have been re-generated from calli, as transformed plantlets would be. No significant variation was observed between the results from these plants and those of Florina shoot tip cultures.