THE EFFECTS OF WHOLE CHROMOSOME SUBSTITUTIONS DIFFERING IN ALLELES FOR HYBRID DWARFING AND PHOTOPERIODIC SENSITIVITY ON TISSUE-CULTURE RESPONSE (TCR) IN WHEAT

The wheat varieties Chinese Spring, Marquis and Thatcher and five inte rvarietal 'Chinese Spring' substitution lines for chromosomes 2B (2 li nes), 2D (2 lines) and 4A, differing from the recipient variety in al leles for hybrid dwarfing genes and/or the photoperiodic response gene s were analysed for tissue culture response (TCR). It could be demonst rated that only chromosome 2B has a major effect on TCR. Allelic varia tion at the hybrid dwarfing loci seems to have no effect on tissue cul ture performance, even in the combination D1D2D3 which gives the grass dwarf phenotype. Also the allelic constitution at the Ppd loci, gave no indication for a direct major effect of those alleles, however ther e seems to exist genetical factors for TCR on the homoeologous group 2 chromosomes which may be closely linked to the Ppd loci.