Genetic engineering offers an alternative method to the conventional breeding of ‘W. Murcott’ mandarin (Citrus sp.), one of the most commercially important cultivars grown in the world. Ahmad Omar from the University of Florida and Zagazig University in Egypt used genetic engineering to confer citrus canker resistance in W. Murcott mandarin.
Transformation of W. Murcott mandarin was achieved by protoplast transformation system using Xa21, a Xanthomonas resistance gene from rice. Ten transgenic lines were developed from the transformation and were subjected to the citrus canker pathogen by syringe inoculation under laboratory conditions. The transgenics showed a reduction in lesion number and bacterial populations within lesions compared to wild type control plants.
This study presents a new approach to confer canker resistance to mandarin oranges. However, the transgenic W. Murcott mandarin lines require further evaluation under field conditions to validate the level of resistance.