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1

Gene segregation in a barley DH population

100%

Szarejko I., Maluszynski M., Polok K., Zbieszczyk J.

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vol. 38

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issue 4

415-424

EN

A large population of anther culture-derived barley regenerants and their progeny was tested for allele segregation at 1 isozyme and 8 morphological marker loci. The segregation of genetic markers was examined separately for haploid, diploid and polyploid regenerants. All the 9 analysed genes except al (albino lemma) on chromosome 3 segregated according to the expected 1 : 1 ratio in the microspore-derived barley population. There was no difference in allele distribution between haploid and diploid regenerants. Among the limited number of 34 analysed tetraploids a significant excess of the dominant allele at locus o (orange lemma) of chromosome 6 was also observed. The recombination frequency between linked genes (n - lk2 on chromosome 1 and r - s on chromosome 7) estimated in the DH population did not differ significantly from recombination rates calculated in F2 progeny or presented in barley chromosome maps. The phenomenon of gametic selection is discussed in relation to the genotype dependency of anther culture response and procedures used for DH production in barley.

2

Cytological and genetic evaluation of anther culture-derived doubled haploids in barley

100%

Szarejko I., Fakl D. E., Janusz A., Nabialkowska D.

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vol. 38

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issue 4

437-452

EN

Gametoclonal variation among anther culture-derived plants of three barley genotypes was estimated on the basis of cytological analysis (DH1, DH2 generation), observation of morphological variants (DH2, DH3) and chlorophyll mutation test (DH2, DH3). Individual head rows were grown in the field to detect possible chimeric structure of regenerants and to assess the number of variants and mutations in each line. Spontaneously doubled plants were the most frequent class (70%) among regenerants and almost 90% of them were completely fertile. There was a difference in proportion of haploids produced by different genotypes, but the highest frequency observed did not exceed 21%. The remaining regenerants were tetraploid, and contained chromosomal mutations or chimeras. In total, there were about 15% of polyploids and plants carrying chromosomal aberrations (translocations, inversions) among DH1 individuals. The changes in chromosome number and structure were the main source of observed variation. The level of gene mutation induced in vitro was relatively low. No more than 1% of microspore-derived plants expressed visible morphological changes in DH2 progeny. Only two morphological variants derived from the Bruce cultivar proved to be homozygous mutants (dwarf type) stable up the to third generation. The frequency of DH plants carrying chlorophyll mutation was 5.8%, but most of them (82%) were chimeric and had only a small mutation sector. The level of gametoclonal variation depended on the donor plant genotype. The highest proportion of variants and mutations was observed among DH plants derived from the Bruce cultivar, while the lowest was recorded among plants regenerated from anther culture of the doubled haploid line H930-36. Mechanisms leading to the observed variation and implications resulting from the presented experiments concerning implementation of anther culture in barley breeding were discussed. It was concluded that this method resulted in a high frequency of spontaneous doubling, a low frequency of genetic changes, and being less time and effort-consuming than the 'Bulbosum' technique, can be applied to most barley breeding programs.

3

Somaclonal selection of physiological mutants and several problems related to rice cell breeding

75%

Kinoshita T., Mori K.

Journal of Applied Genetics

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1998

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vol. 39

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issue 1

9-35

EN

Tolerance to a new herbicide, pyributycarb, was evaluated both at the plant and cellular levels. Several highly or moderately tolerant strains chosen at the plant level, showed a parallel relation of to tolerance at the cellular level. However, on the whole, correlation between total tolerance indices and survival rates of calli was not significant in 18 out of the 80 studied strains. As a result of somaclonal selection for two herbicides, lines NB-200 and NM-100 were regenerated from the tolerant calli screened with benthiocarb at 200 ppm, and molinate at 100 ppm, respectively. In the R2 generation, both the lines displaned a stable tolerance both at the plant and cellular levels. Thus the highly tolerant mutant lines were developed from a moderately tolerant line, N-61, via in vitro selection. To achieve a short-cut method in the interspecific genetic exchange, a series of techniques related to cell fusion were established in rice and related species. Two kinds of somatic hybrids between the cultivar Kitaake and tetraploid Oryza species, O. punctata and O. officinalis, were successfully produced. Among the somatic hybrid plants, a wide range of chromosomal variation was observed. Aneuploid plants with a chromosome number around 2n = 72 (hexaploid), which are expected from a symmetric fusion between diploid and tetraploid strains, were obtained showing mixoploidy within a plant. Most of the somatic hybrids were characterized by intermediate features of plant-type showing high sterility, shattering of spikelets and reduced plant height. As an exception, a diploid plant, which was identified by RFLP analysis using the rDNA gene probe, closely resembled Kitaake and produced viable seeds. A tetraploid hybrid plant was also promising for the introduction of economically important characters through the reduction of chromosome numbers by doubled haploids. Gametoclonal variation and gamma radiation was applied to Kitaake. The mutation frequency was prominently increased by gamma ray treatment, especially at high doses of 200 Gy or 300 Gy. In the M3R2 or M4R3 generations, most of the variants showed unfavourable characters. Most of the mutant characters were governed by single or double recessive genes. Several mutants such as short culm and early flowering time might be used for rice breeding.

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3 Journal of Applied Genetics

1 1998

2 1997

2 Szarejko I.

1 Fakl D. E.

1 Janusz A.

1 Kinoshita T.

1 Maluszynski M.

1 Mori K.

1 Nabialkowska D.

1 Polok K.

1 Zbieszczyk J.

Gene segregation in a barley DH population

Cytological and genetic evaluation of anther culture-derived doubled haploids in barley

Somaclonal selection of physiological mutants and several problems related to rice cell breeding