RESUMEN
KEY MESSAGE: Short-term heat stress during male meiosis causes defects in crossover formation, meiotic progression and cell wall formation in the monocot barley, ultimately leading to pollen abortion. High temperature conditions cause a reduction of fertility due to alterations in meiotic processes and gametogenesis. The male gametophyte development has been shown to be particularly sensitive to heat stress, and even short-term and modest temperature shifts cause alterations in crossover formation. In line with previous reports, we observed that male meiosis in the monocot barley exposed for 24-45 h to heat stress (32-42 °C) partially or completely eliminates obligate crossover formation and causes unbalanced chromosome segregation and meiotic abortion. Depending on the severity of heat stress, the structure and organization of the chromosomes were altered. In addition to alterations in chromosome structure and dynamics, heat treatment abolished or reduced the formation of a callose wall surrounding the meiocytes and interrupted the cell cycle progression leading to cytokinesis defects and microspore cell death.
Asunto(s)
Hordeum , Infertilidad Masculina , Citocinesis , Respuesta al Choque Térmico , Hordeum/genética , Humanos , MeiosisRESUMEN
Camelina sativa L. Crantz (Brassicaceae family), known as camelina, has gained new attention as a re-emerging oil seed crop. With a unique seed oil profile, with the majority of the fatty acids consisting of linolenic (C18:3), oleic (C18:1), linoleic (C18:2), and eicosenoic (C20:1), camelina oil is reported to be useful as a food oil and biofuel. However, there are still many unknown factors about the structure and genetic variability of this crop. Chromosomal localization of ribosomal DNA was performed using fluorescence in situ hybridization (FISH) with 5S rDNA and 25S rDNA sequences as molecular probes on mitotic chromosomes of enzymatically digested root-tip meristematic cells. Here, we present for the first time a comparative analysis of selected genotypes (cultivars, breeding lines and mutants) of C. sativa with the use of cytogenetic techniques. The main aim of the study was to determine the intraspecific and interspecific polymorphisms in the structure of chromosomes of selected accessions using conserved 5S and 25S rDNA repetitive sequences as molecular probes. The results were compared with C. microcarpa (closely related to C. sativa) rDNA gene loci distribution. The presence of minor rDNA sites was discussed and compared with other Brassicaceae species. In addition, demonstration karyograms of C. sativa and C. microcarpa mapped with rDNA probes were prepared based on the cv. "Przybrodzka" and GE2011-02 genotype, respectively. The use of 5S and 25S rDNA probes provided an insight on the genome structure of C. sativa at the cytogenetic level and can help to understand the genome organization of this crop. The putative role of cytogenetic markers in phylogenetic analyses of camelina was discussed, as well.