PRODUCTION OF MICROPROTOPLASTS FROM Citrus SUSPENSION CELLS FOR USE IN CHROMOSOME TRANSFER

Texas A&M University-Kingsville, Citrus Center, P.O. Box 1150, Weslaco, TX 78599 USA

Microprotoplast mediated chromosome transfer(MMCT) provides a direct way to transfer a single chromosome from a donor to a recipient species.In mammalian cells, this procedure has been a powerfull tool for gene mapping and to study the regulation of gene expression. Until recently, no treatment was known for an efficient induction of micronuclei in plants, which delayed the application of MMCT in plants. Recently, Amiprophos methyl and Cremart was found to be very efficient for mass induction of microprotoplasts in the Solanaceae family, and an MMCT procedure was established in that family. For crops with strong breeding barriers such as citrus, MMCT could be a alternative breeding strategy. A limited portion of the genome of a donor species could be transferred to a recipient species creating the genetic variability needed in cultivars of sweet orange and grapefruit. Additionally, MMCT would open new opportunities for genetic studies in citrus. An overview of the MMCT technology and its potential use in fruit crops will be presented with enphasis on the procedure being developed in our laboratory.