نتایج جستجو برای: immature pollen
تعداد نتایج: 47880 فیلتر نتایج به سال:
Successful sexual reproduction in animals and plants requires communication between male and female gametes. In flowering plants, unlike in animals, eggs and sperm cells are enclosed in multicellular embryo sacs and pollen grains, respectively; guided growth of the pollen tube into the ovule is necessary for fertilization. Pollen tube guidance requires accurate perception of ovule-emitted guida...
Pollen allergies have been rapidly increasing over the last decades. Many allergenic proteins and non-allergenic adjuvant compounds of pollen are involved in the plant defense against environmental or microbial stress. The first aim of this study was to analyze and compare the colonizing microbes on allergenic pollen. The second aim was to investigate detectable correlations between pollen micr...
Pollen morphology characterization is important in taxonomy, conservation and plant breeding, and pollen viability studies can support breeding programs. This study investigated pollen morphology and male fertility in 18 species of Bromeliaceae with ornamental potential. For morphological characterization, pollen grains were acetolyzed and characterization of exine was done using scanning and t...
We evaluated a 4x accession of Ipomoea batatas (L.) Lam. and four 2x accessions of Ipomoea triloba for 2n pollen production. Approximately 90% of the genotypes of accession 81.2 (I. batatas, 4x) produced 2n pollen with different frequencies. In contrast, none of the genotypes of I. triloba produced 2n pollen. The diameter of the 2n pollen was approximately 30% ((3) sqrt 2) larger than that of t...
Despite much effort, a robust protocol for in vitro germination of Arabidopsis thaliana pollen has been elusive. Here we show that controlled temperatures, a largely disregarded factor in previous studies, and a simple optimized medium, solidified or liquid, yielded pollen germination rates above 80% and pollen tube lengths of hundreds of microns, with both Columbia and Landsberg erecta (Ler) e...
There is little clinical evidence for a correlation between the severity of atopic eczema (AE) and pollen exposition. To obtain more data, we performed a clinical cohort pilot study about the influence of pollen on AE between sensitized and nonsensitized subjects and an experimental study addressing the cutaneous penetration of pollen into the skin. Fifty-five patients were monitored during bir...
Variation in the number of pollen apertures has been widely described among and within angiosperm species. Apertures are weak points of the pollen wall where the pollen tube germinates. Pollen aperture heteromorphism (pollen grains with different numbers of apertures in a single individual) is common in flowering plants, whereas polymorphism (among-individual variation) is rare. Previous work o...
BACKGROUND Aeroallergen sampling provides information regarding the onset, duration and severity of the pollen season that clinicians use to guide allergen selection for skin testing and treatment. OBJECTIVES This atmospheric survey reports (1) airborne pollen contributions in Adana in one-year period (2) pollen onset, duration and peak level (3) the relationship between airborne pollen and s...
BACKGROUND Specific allergen from various pollen types has been found to be carried through the outdoor air, not only by intact pollen grains, but also by much smaller, paucimicronic particles. There is no complete agreement on whether, for birch (Betula), the seasonal appearance of atmospheric pollen allergen follows the fluctuation pattern of the pollen season. METHODS Assessment of birch-p...
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