II. 30. Some aspects of tissue culture of barley.
S. Malepszy, Warsaw Agricultural University, Institute of Genetics and Plant Breeding, 02766 Warsaw, Nowoursynowska 166, Poland; and M. Gaj, Silesian University, Institute of Molecular Biology, 40032 Katowice, ul. Jagiellofiska 28, Poland.
The barley is a plant in which culture of somatic cells is not practically used for the purpose of genetics. This is so because the factors which limit the growth of callus and differentiation of buds or embryoids are not known. As yet only Cheng and Smith (1975) and Köblitz and Saalbach (1976) have obtained some plants originating from callus cultures initiated from shoot meristems.
Our work in culture of somatic tissue from barley has been started by the study of reaction of 23 varieties and 50 mutants on the medium EM1. The mutants have been obtained after chemical mutagenesis of seeds from variety "Julia" (in the M4 and M5 generations). The explants were isolated from 3-day old seedlings growing from excised embryos. The following explants were used: (1) root meristems, (2) non-meristematic roots parts, (3) leaf blades and coleoptile. On each medium 12-16 meristems and 20-24 other explants were tested (four explants in one Petri dish). The basal medium used was from Linsmaier and Skoog (1965) with various sucrose and growth regulator concentrations (Table 1).
On the medium EM1 great differences in the ability of mutants and varieties to callus formations and growth from root meristems are observed. All the genotypes (mutants and varieties) can be classified in the following four groups: (1) callus initiation by 50-90% of explants, rapidly growing white tissue, (2) callus initiation by 20-50% of explants, slower growing tissue, (3) callus initiation by about 20% of explants and later following browning and death, and (4) failed in callus initiation. The numbers of varieties and mutants were nearly the same in the first three groups, but to the fourth group only a few genotypes belonged.
On the same medium the non-meristematic root and shoot explants produced callus only sporadically. In the case of shoot explants only the coleoptile developed callus which was, however, very short lived.
The further experiments in culture of both root explants on the medium EM45 gave unexpected results (Figure 1), because all varieties and four mutants tested (two from the group IV and one from I and III) produced good callus (90-100%). Callus initiation and growth from coleoptile was frequently observed, but not from leaf blades.
The non-meristematic root parts isolated from 4 weeks old plants required in culture higher 2,4-D concentration (medium EM46) and gave good growing callus from about 90% of explants. The best callus growth by further culture has been obtained from varieties Amsel, Ortolan, Bulchi Gofa and Union using the medium EMr2. On this medium only the variety "Union" has differentiated some green shoots.
The following conclusion can be derived from our work: (1) the varieties and mutants of barley show great variability in callus formation and/or growth on the medium, (2) great genotypic differences for callus initiation and growth can be mostly eliminated through high osmotic pressure of the medium. One of the important findings is that, after mutagenesis in a variety which failed to grow in vitro ("Julia"), the same reaction spectrum can be obtained which exists in commercial varieties.
References:
Cheng, T.Y. and H.H. Smith. 1975. Planta 123:307.
Köblitz, H. and G. Saalbach. 1976. Biochem. Physiol. Pflanzen 123:307.
Saalbach, G. and H. Köblitz. 1977. Biochem. Physiol. Pflanzen 171:469.
Linsmaier E.M. and F. Skoog. 1965. Physiol. Plantarum 18:100.
