Submitted to: Journal of Japanese Society of Horticultural Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 6/28/1996
Publication Date: N/A
Interpretive Summary: New techniques are being characterized for breeding new citrus plants with better fruit quality and/or rootstalk traits that cannot be obtained using classical plant breeding techniques. An electrically induced combination of plant cells from two different plant species, called "cell fusion," is being used to create new varieties of citrus plants from exisiting citrus species and related, but sexually incompatible, plant species. Using this technique, this paper demonstrates that several additional wild relatives of citrus can be combined with commercial citrus species to create new citrus hybrids. These hybrids will be evaluated for use as new fruit varieties or as rootstocks for existing fruit cultivars. New fruit varieties will help increase the market for citrus fruit and juice, new rootstocks will be selected for better resistance to disease, cold stress, and increased fruit yields.
Technical Abstract: Electrofusions between embryogenic callus protoplasts from Citrus species and mesophyll protoplasts from other Aurantioideae representatives, including Clauseneae, Triphasiinae, Balsamocitrinae, and Citrinae, were performed to estimate the range within which fusion could produce embryos. Production and regeneration of hybrids between Citrus and allied species depended on the taxonomical distance of the parents; the closer the mesophyll parent were taxonomically to Citrus, the greater the potential of forming viable hybrid plants. The most successful fusions were obtained between Citrus and other Citrinae species. Most of these combinations produced embryos that generated normal plantlets with good rooting ability. Embryoids from fusions with Balasamocitrinae species initiated numerous adventitious buds, but they were incapable of rooting. When these shoots were grafted onto existing stocks, some produced deformed leaves. In fusions between Citrus and Clausenae species, most of the regenerated shoots were weak and abnormal, but a few normal plantlets were rescued. In fusions with Triphasiinae species, the embryos which survived failed to develop shoots. Thus, from fusions involving Triphasiinae species which are considered closer to Citrus than are Clausenae species, we were unable to regenerate any somatic hybrids.