Establishment of somatic hybrid cell lines between Zea mays L. (maize) and Triticum sect, trititrigia MacKey (trititrigia)

Abstract

Somatic hybrid cell lines were constructed by the fusion of protoplasts isolated from cell suspensions of Zea mays L. (maize, 2n = 20) and Triticum sect, trititrigia MacKey (trititrigia, 2n = 35), a perennial hybrid of T. durum Desf. and Elytrigia intermedium (Host) Nevski. Iodoacetamide-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, approximately 0.002% of the total protoplasts cultured following fusion treatment developed into cell colonies, and 79 lines of them, almost a half, were singled out and subcultured. Among the subcultured lines three 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 DNAs with a mitochondrial gene, atpA., from pea, or a chloroplast gene, trnK, from rice, revealed that all the hybrids carried only the organellar DNAs of trititrigia, which excluded the possibilities of a chimeric callus or any DNA contamination. Cytogenetically, one hybrid was mixoploid with a 2n of 46-67 in which chromosomal endoreduplication, characterized by the appearance of diplochromosomes, was occasionally observed. Its hybridity was reconfirmed by the fact that it bore the satellite chromosomes of both maize and trititrigia, which were distinguishable from each other by size. In contrast, the other two hybrids were aneuploids. The potential of gene transfer between Zea and Triticum species was thus conclusively established.

Intergeneric somatic hybridization and its application to crop genetic improvement

“…Hall et al (1992a, b) found that more chromosome breakage was detected in the UV-treated cells than gamma-treated cells at the same biological dosage. In addition to the irradiation, restriction endonuclease, spindle toxin or chromosome condensation agents have also been and Dudits et al (1987) Petroselium Dudits et al (1980) Petunia Li et al (1982, Pental et al (1986) and Dragoeva et al (1999) Glimelius and Bonnett (1986) Xia et al (1998) and Zhou et al (2001aZhou et al ( , b, 2002a, b) Zea Wang et al (1993) and Szarka et al (2002) Xu et al (2003 …”

“…But major differences in chromosome morphology and size between the fusion parents could facilitate hybrid verification based on karyotype analysis, which can also reveal parental chromosome contribution to the hybrids. Verification of hybrids via chromosome morphology difference has been used in characterizing a number of somatic hybrids (Kao, 1977;Binding and Nehls, 1978;Chien et al, 1982;Gleba et al, 1982Gleba et al, , 1988Gupta et al, 1984;Kushnir et al, 1987;Endo et al, 1988;Hinnisdaels et al, 1991;Kostenyuk et al, 1991;Babiychuk et al, 1992;Ahuja et al, 1993;Wang et al, 1993;Skarzhinskaya et al, 1996;Kisaka et al, 1998;Xing et al, 2001;Szarka et al, 2002).…”

“…Protoplasts of the fusion parents have been treated with ionizing radiation or metabolic inhibitors that prevent the division of the unfused or homofused protoplasts Yamagishi et al, 2002). The heterokaryons could grow smoothly and finally develop into hybrid callus or plants, due to genetic or physiological complementation (Kostenyuk et al, 1991;Wang et al, 1993). In some cases low or no regeneration capacity of parental protoplasts could be used for hybrid selection because the morphogenic potential of the fusants could be restored due to complementation (O'Neill et al, 1996;Xia et al, , 2003Hansen, 1998;Zhou et al, 2001a, b;Hu et al, 2002a;Xu et al, 2003).…”

Using breeding and quantitative genetics to understand the C4 pathway

“…There have also been attempts to form hybrids between wheat and C 4 grasses. A cell suspension of Trititrigia (a perennial hybrid of Triticum durum and Thinopyrum intermedium ) was hybridized with maize ( Wang et al , 1993 ; Wang and Niizeki, 1994 ). Plants that regenerated were aneuploids carrying incomplete sets of chromosomes from both species.…”