Utilization of haploids for producing of mutants
--Valery Tyrnov

In our laboratory, the technology for matroclinal haploid production in great numbers was developed (Apomixis Newsletter, 1992, 6:6). Haploids were tested during 5 years of experiments as the objects for mutation breeding. Ionizing radiation and chemical mutagens were used. The apical meristem of seedlings, dry seeds with haploid embryos, ears and seeds of maternal forms were influenced. Haploids, in comparison with diploids, are 2-3 times more sensitive to irradiation (as to inhibition and lethal effects). However, the level of chromosomal aberrations in haploids was 30-90% lower. Perhaps it is conditioned by more extensive damage of haploid cells and their non-participation in mitotic cycles. All haploids after mutagenic treatments were changed. Diploids had no changes. Diploid self-pollinated mutant progeny, obtained from haploids, frequently were heterozygous, if apexes or even seeds with haploid embryos were influenced. Probably, this is connected with the appearance of different mutations in ears and panicles. The best variant for production of homozygous mutants from haploids consisted in treatment by mutagens of initial diploid maternal forms. The mutant forms with changed vegetation time, morphology, and color were obtained in different lines. In Mangelsdorf's tester, in addition, mutants for certain genes were produced. The appearence of white and light green stripes on leaves was a typical phenomenon after mutagenic treatment of seedlings and seeds with haploid embryos. It may be used as the test for estimation of different factors on mutagenic activity and also in ecological investigations of surrounding pollution.
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