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The aim of the research was to make a preliminary determination of the effectiveness of the in duc tion of haploids in Capsicum frutescens L. In order to induce androgenesis red and yellow fruit forms of species were used, each bred by the re searchers on their own. The experiment was per formed in October. An ther cultures were conducted according to a modified me - thod developed by Dumas et al. (1981) for C. annuum L. The anthers were laid on CP medium con taining 0.01 mg·dm⁻³ 2.4-D and 0.01 mg·dm⁻³ kinetin, with the addition of 0.5 g·dm⁻³ of activated carbon and 5 mg×dm⁻³ of silvernitrate, solidified with 8 g·dm⁻³ of agar. The cul tures were in cu bated in the dark at 35 deg C for 8 days. Next they were trans ferred to 25 deg C under a 12-hour photoperiod. After 14 days of induction, anthers were trans ferred to R₁ medium supplemented with 0.1 mg·dm⁻³ kinetin. Obtained embryos were subsequently transplanted onto V₃ hormone-free me dium and well growing plants were planted in green houses. The efficiency of androgenesis for both C. frutescens L. forms was relatively low and it did not exceed 5 %. The ploidy level of the result ing plants was determined by flow-cytometric analysis. The regenerants con sisted of about equal numbers of haploids and diploids. Additionally, among plants regenerated from anthers of yellow fruit forms, two mixoploids were observed.
Microspore derivatives occurring in culture of maize microspores were studied by light and electron microscopy. The cultures showed a high degree of heterogeneity throughout the whole period of cultivation. Several types of androgenic structures at different developmental stages were observed, indicating a high level of asynchrony among microspores following the androgenic pathway. During the first 5 to 7 days of culture, multicellular structures developed inside the exine. At later stages of culture the developing microspores ruptured the pollen wall and formed structures variable in cellular characteristics. Three main types were distinguished: (i) one-domain structures consisting of small or large cells only; (ii) two-domain structures with large and small cells, the domains differing in size and cellular characteristics; (iii) callus-like structures. The two-domain structures seem to resemble zygotic proembryos which also contain two different parts, the suspensor and the apical region. The observed variability is most likely related to differences in gene activity during the inductive stage of androgenesis and the genetic properties of the microspores themselves, rather than to the conditions of in vitro culture.
The androgenetic response of several selected male sterilitymaintainer genotypes of triticale was investigated. Androgenesis induction was obtained in all cultivars, but a large genotypic variation in green plant regeneration was observed. The number of regenerated triticale plants varied from 0.1 to 4.7 green plants per spike, depending on genotype. Spontaneous doubling of chromosomes varied from 14 to 60 % for particular genotypes and, on average, reached the value of 34 % for all genotypes. Fertile DH lines obtained in this study will find practical application in the development of triticale male sterile lines that are desirable in hybrid breeding.
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