ESTABLISHMENT OF SOMATIC HYBRID CELL-LINES BETWEEN ZEA-MAYS L (MAIZE)AND TRITICUM SECT TRITITRIGIA-MACKEY (TRITITRIGIA)

Somatic hybrid cell lines were constructed by the fusion of protoplast s isolated from cell suspensions of Zea mays L. (maize, 2n = 20) and T riticum sect. trititrigia MacKey (trititrigia, 2n = 35), a perennial h ybrid of T. durum Desf. and Elytrigia intermedium (Host) Nevski. Iodoa cetamide-inactivated protoplasts of maize were fused with trititrigia protoplasts, which were sensitive to the PEG/DMSO fusion treatment at high pH and high calcium. Based on physiological complementation, appr oximately 0.002% of the total protoplasts cultured following fusion tr eatment developed into cell colonies, and 79 lines of them, almost a h alf, were singled out and subcultured. Among the subcultured lines thr ee were, in comparison with the parents, identified as somatic hybrids by their coupled XbaI restriction patterns of total DNAs probed with the ribosomal DNA of rice. Southern analysis of the digested total DNA s with a mitochondrial gene, atpA, from pea, or a chloroplast gene, tr nK, from rice, revealed that all the hybrids carried only the organell ar DNAs of trititrigia, which excluded the possibilities of a chimeric callus or any DNA contamination. Cytogenetically, one hybrid was mixo ploid with a 2n of 46-67 in which chromosomal endoreduplication, chara cterized by the appearance of diplochromosomes, was occasionally obser ved. Its hybridity was reconfirmed by the fact that it bore the satell ite chromosomes of both maize and trititrigia, which were distinguisha ble from each other by size. In contrast, the other two hybrids were a neuploids. The potential of gene transfer between Zea and Triticum spe cies was thus conclusively established.