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Historically, traditional crossbreeding schemes have predominated in oat breeding. In vitro culture techniques seek to expedite the breeding process and enhance selection efficiency. Maximum yields are achieved from hybrid plants produced by crossing pure (homozygous) lines with the desired traits. Homozygous lines can be produced through conventional breeding methods, which are time-consuming and costly. Alternatively, the production of homozygous lines can be accelerated by producing doubled haploid (DH) plants derived from (haploid) male gametophytes or their microspores (androgenesis). This method condenses the various stages required for producing homozygous lines in a single generation, resulting in significant time and cost savings. These and other advantages render androgenic DHs the preferred choice in numerous important crops where any of the various in vitro experimental techniques (anthers culture or isolated microspores culture) are well-established. However, in the case of oat (Avena sativa L.), an efficient plant regeneration method remains not very effective compared to the most common cereals, possibly due to the known recalcitrance of this cereal to in vitro culture. This review presents the methods through anther and microspore cultures utilized in the production of oat DHs revealing the crucial factors influencing the efficiency of this method in oat (Avena sativa L.). [ABSTRACT FROM AUTHOR]

As a result of oat (Avena sativa L.) × maize (Zea mays L.) crossing, maize chromosomes may not be completely eliminated at the early stages of embryogenesis, leading to the oat × maize addition (OMA) lines development. Introgression of maize chromosomes into oat genome can cause morphological and physiological modifications. The aim of the research was to evaluate the leaves' anatomy, chlorophyll a fluorescence, and yield parameter of oat doubled haploid (DH) and OMA lines obtained by oat × maize crossing. The present study examined two DH and two disomic OMA lines and revealed that they differ significantly in the majority of studied traits, apart from: the number of cells of the outer bundle sheath; light energy absorption; excitation energy trapped in PSII reaction centers; and energy dissipated from PSII. The OMA II line was characterized by larger size of single cells in the outer bundle sheath and greater number of seeds per plant among tested lines. [ABSTRACT FROM AUTHOR]

A critical step in the production of doubled haploids is a conversion of the haploid embryos into plants. Our study aimed to recognize the reasons for the low germination rate of Avena sativa haploid embryos obtained by distant crossing with maize. Oat cultivars of 'Krezus' and 'Akt' were investigated regarding embryo anatomy, the endogenous phytohormone profiles, and antioxidant capacity. The zygotic embryos of oat were used as a reference. It was found that twenty-one days old haploid embryos were smaller and had a less advanced structure than zygotic ones. Morphology and anatomy modifications of haploid embryos were accompanied by extremely low levels of endogenous auxins. Higher levels of cytokinins, as well as tenfold higher cytokinin to auxin ratio in haploid than in zygotic embryos, may suggest an earlier stage of development of these former. Individual gibberellins reached higher values in 'Akt' haploid embryos than in the respective zygotic ones, while the differences in both types of 'Krezus' embryos were not noticed. Additionally to the hormonal regulation of haploid embryogenesis, the poor germination of oat haploid embryos can be a result of the overproduction of reactive oxygen species, and therefore higher levels of low molecular weight antioxidants and stress hormones. [ABSTRACT FROM AUTHOR]

Background. Development of new cultivars is one of the vital options for adapting agriculture to climate change, and the production of doubled haploid (DH) plants can make a significant contribution to accelerating the breeding process. Oat is one of the cereals with particular health benefits, but it unfortunately still remains recalcitrant to haploidization. Our previous studies have clearly demonstrated that post-pollination with hormone treatment is a key step in haploid production through wide hybridization and indicated it as the most effective method for this species. Therefore, we subsequently addressed the problem of the influence of 2,4-dichlorophenoxyacetic acid (2,4-D) concentration on consecutive stages of DH production. Methods. Twenty-nine genotypes were tested, 9,465 florets were pollinated with maize pollen 2 days after emasculation and then treated with 2,4-D at 50 mg/L and 100 mg/L. Results. The applied treatments did not reveal any differences in the number of obtained haploid embryos. However, almost twice as many haploid plants formed on MS medium after applying a higher auxin concentration and 20% more successfully acclimatized. Moreover, 100 mg/L 2,4-D treatment resulted in twice as many DH lines that produced almost three times more seeds compared to 50 mg/L treatment. Nevertheless, the results have confirmed the existence of strong genotypic variation, which may significantly limit the development of an effective and economically feasible method that could be incorporated into breeding programs. [ABSTRACT FROM AUTHOR]

The development of embryos requires interaction of many endogenous hormones. The aim of the study was to determine which endogenous phytohormones are involved in the process of oat (Avena sativa L.) haploidization. Oat haploids were obtained by wide crossing with Zea mays L. The hormonal profiles of the ovaries with (OE) and without developed embryo (OWE) were compared. Phytohormone contents were measured by UHPLC coupled with mass spectrometer. The total content of indole-3-acetic acid (IAA), trans-zeatin (tZ), and kinetin (KN) in OE was significantly higher than in OWE. 4-Chloroindole-3-acetic acid was detected only in OWE. There were no differences between OE and OWE in the content of gibberellins (GA1, GA3, GA4, GA6, GA7) and stress hormones (abscisic, salicylic, jasmonic acids). Content of endogenous KN was highly negatively correlated with the percentage of haploid embryos, germinated haploid embryos, haploid plants on MS (in vitro), haploid plants in soil (ex vitro), and doubled haploid lines. The tZ content negatively correlated with the frequency of haploid embryo formation, germination, and haploid plants obtained in vitro, as opposed to GA1, which correlated positively. A positive correlation was found between IAA and tZ in OE, whereas in OWE it was a negative correlation. The profiles of phytohormones in OE and OWE were determined; however, their mode of action needs to be clarified. [ABSTRACT FROM AUTHOR]

The objective of this study was to facilitate the resistance of barley to Fusarium culmorum according to direct (disease rating (DR), fresh weight) and indirect (physiological and biochemical) parameters. Significant correlations were detected between most measured parameters. Hulled lines revealed less root susceptibility to infection of F. culmorum expressed in DR and fresh weight. Infection in roots significantly increased phenolics content, especially in most hull-less genotypes, but decreased soluble sugars, pigment content and overall performance index of the PSII photosystem. Significant correlations suggest the possibility of applying the measured indirect parameters in selection of barley DH lines resistant to F. culmorum infection. [ABSTRACT FROM AUTHOR]