The widely spread onion belonging to Alium cepa L., is know to be severely
affected by the soil born disease, white rot. Infected soils totally prevents the
production of onion for a period up to ten years, which dramatically reduced the
economic production of onion in Egypt and limited the exportation of Egyptian onion
during the last decade. There were no source of resistance ¡n the cultivated onion. As
an attemptation to pick out a source for resistance, a survey was made among other
relatives belonging to Alium sp. Resistance was found in Alium odorum sp. and Alium
tuberosum sp. Interspesific crosses were made for many years to transfer resistance
ability to Egyptian onion cultivars, but normal crossing was always incomplete and
embryos fail to develop normally. Tissue culture techniques were used to resque the
embryos resulted from the cross between A. cepa and A. odorum. Embryos were
collected and an array of media with different hormone combinations were examined.
In this study a very rare percent of embryos succeeded to complete its development
and produced plantlets.