Pollen viability and pollen vigor.

Investigations were carried out to correlate pollen viability, assessed on the basis of a fluorochromatic reaction (FCR) test, with pollen vigor, assessed on the basis of the time taken for in vitro germination in pollen grains subjected to high humidity (>95% RH) and temperature (38 °C) or storage stress of Nicotiana tabacum, Agave sp., Tradescantia virginiana, and Iris sp. Both high RH and temperature, as well as storage stresses, affected pollen vigor before affecting pollen viability. The results are discussed in the light of available data on the viability and vigor of stressed pollen and of aged seeds. The need for consideration of pollen vigor, particularly in stored pollen, the inadequacy of the methods presently used, and some of the methods suitable to assess pollen vigor are elaborated.

Temperature effects on self incompatibility in Lilium longiflorum.

Detached pistils of the clonal variety, Lilium longiflorum 'Aral No. 5', were submerged before pollination in 50°C water for 0, 1, 2, 3, 4, 5, 6 or 7 min and then immediately compatibly and incompatibly pollinated. Incompatibility, as indicated by pollen tube length after 48 h at 23.5°C, was eliminated by a 1-2 min submersion while compatibility was removed by a 4-5 min one. The 'window' of incubation temperatures at which incompatible and compatible pollen tubes are clearly differentiated occurred between 15 and 30°C.

Wall-bound proteins of pollen tubes after self- and cross-pollination in Lilium longiflorum.

Wall-bound proteins of Lilium longiflorum pollen tubes grown in vivo constitute 20-27% of the dry matter. Twenty-two-twenty-six percent of these proteins are NaCl soluble. Wall-bound proteins of in vivo pollen tubes are present in amounts 5-7 times that found in tubes grown in vitro. The protein pattern of wall-bound proteins is different between in vitro and in vivo grown pollen tubes. There are two kinds of pollen tube wall proteins: loosely bound and tightly bound. The latter are NaCl insoluble, contain hydroxyproline and are assumed to be covalently bound. No significant differences have been found in the amount of wall-bound proteins present between pollen tubes resulting after self-pollination and those resulting from cross-pollination. However, some band differences between self- and cross pollen tubes have been observed after gel electrophoresis. It can be supposed that some wall-bound proteins of pollen tubes are associated with the incompatibility reaction.

Cell-wall proteins in pollen and roots of Lilium longiflorum: extraction and partial characterization.

Cell-wall proteins of pollen grains, in-vitro-germinated pollen and young roots of Lilium longiflorum were studied by gel electrophoresis and amino-acid analysis. The proteins were removed from extensively purified walls by successive saline and alkali extractions. The major part including the hydroxyproline-containing proteins is covalently bound to the wall. Clear differences were observed between the proteins, especially the glycoproteins, of the pollen grain and the pollen tube. During elongation of the tubes some proteins decrease in quantity and many new proteins appear. The amount of protein in the cell walls is much lower in roots than in pollen and the root cell walls also contain fewer glycoproteins.

Studies on the self-incompatibility of Petunia hybrida in excised-style culture. Differences in self-incompatibility reaction among four clones.

In Petunia clones with different S-alleles, self- or cross-pollinated excised-styles of 5, 10, 15, 20 or 25 mm were incubated on a standard agar medium for 24, 48 or 72 h. The length and number of protruding incompatible pollen tubes were compared with those of compatible ones. Throughout the experimental period, the length and number of incompatible pollen tubes of pollen from the S1S1-clone were always less than those of compatible ones. In pollen from S2S2-, S3S3- and S2S3-clones the incompatible pollen tube growth was barely arrested in 5 and 10 mm excised-styles during the first 24 h of incubation. However, inhibition of incompatible pollen tube growth was strengthened with the increase of both excised-style length and incubation period: this was clearly evident in 15 mm or longer excised-styles incubated for 48 h. Ratios of incompatible to compatible pollen tube length in excised-styles incubated for 72 h, were for S3S3 pollen tubes = 0.28, S1S1=0.48, S2S3 = 0.50, and S2S2 = 0.60, and ratios on tube numbers were S3S3 = 0.01, S1S1 = 0.1, S2S2 = 0.21, and S2S3 = 0.21. These results were in agreement with those of in vivo self-pollination. The incompatibility reaction seemed strongest in S3S3-, weaker in S1S1 - and weakest in S2S2- and S2S{3}-clones, and therefore the intensity of S-allele expression would be S3> S1> S2.

Localization of phytic acid in the floral structure of Petunia hybrida and relation to the incompatibility genes.

In three clones of Petunia hybrida with different incompatibility genes, phytic acid is detected exclusively in pollen, stigma and style. These are all parts of the floral structure involved in the incompatibility reaction. Phytase activity was detected in these tissues as well as in the ovary. The level of phytic acid and phytase activity varied between clones with different S alleles. This difference was most evident in stigma and style. The pattern of phytic acid breakdown following pollination depends on whether pollen and style form a compatible or incompatible combination. Incompatible pollination results in a higher rate of degradation. Consideration is given to the relationship between breakdown of phytic acid to myo-inositol and cell wall thickening and plug formation, which occurs to a greater extent in the incompatible combination.

Protein synthesis in germinating pollen of Petunia: role of proline.

Pollen of Petunia hybrida was germinated in artificial medium. At the beginning of the incubation, a large amount of proline, which comprises about half of the total free amino acid pool, was released into the medium. Part of this proline is reutilized by the pollen. Uptake of radioactive amino acids and their incorporation into proteins were studied. The highest rate of protein synthesis was found directly after the onset of germination. The endogenous free proline pool was found to be compartmentalized; one of the compartments is the protein precursor pool; its size is probably much less than 50% of the total free proline in the pollen.

House-dust community (Fungi, mites) in different climatic regions.

House-dust flora and fauna were compared in the maritime cool temperate climate (in three degrees of continentality), the mediterranean warm temperate climate, the arctic climate and the tropical climate.An inverse relationship exists between continentality of the temperate climate and the numbers of arthropods and fungi (mesophilic as well as xerophilic) in the dust of the houses.The numbers of arthropods and fungi were lowest in mediterranean and arctic climates, most likely because of the limiting effect of the drier indoor climate. Fungi are more tolerant of dry conditions than house-dust inhabiting mites. Generally the highest numbers of fungal diaspores and arthropods were found in the tropics, where, however, the lowest number of positive samples was also found, especially for the species of the Aspergillus glaucus group and for Wallemia sebi. Maritime cool temperate climate showed the highest numbers of positive samples for fungi and mites.In general, a relationship exists between relative humidity and the density of fungal diaspores and arthropods.

The formation of allergens during the development of rye pollen (secale cereale).

During pollen development loading of pollen grains of rye with allergen(s) takes place in the anther. Young microspores after meiosis have no allergenic activity. Under greenhouse conditions rye pollen becomes allergenically active about 6 days before release of pollen grains from the anther.

Yield stability and population diversity in oats (Avena sp.).

The relationship between yield stability and populations containing various numbers and combinations of diverse homozygous and homogeneous lines was examined in an environment in which considerable variability occurs among and within growing seasons. Two groups (1,2), each containing 15 populations (4 pure lines grown singly and 11 multilines consisting of mechanical mixtures of all possible 2,3 and 4 way combinations of these 4 pure lines) were tested in each of 5 consecutive years. The pure lines in group 1 and 2 were selected on the basis of previous yield and yield variability respectively. In group 1, no significant differences were found among the 5 year means or the deviation mean squares of the 15 populations but highly significant differences among regression coefficients were present. The regression coefficients of the 4 pure lines differed considerably, indicating that this stability parameter was genetically influenced. The regression coefficients of the multilines tended towards unity regardless of the regression coefficients of the pure lines involved. In group 2, highly significant differences were found among the 5 year means, regression coefficients and deviation mean squares of the 15 populations. No consistent, predictable pattern was apparent between the mean and stability values of the pure lines and the multilines in which they were included. Differences between the 2 groups suggest that higher yield and greater stability result in the multilines if relatively high yielding pure lines are selected for inclusion. In general, the results indicated that multilines containing a number of diverse homozygous and homogeneous pure lines have satisfactory yields and enhanced yield stability. However, adequate testing of the pure lines and potential multilines over a broad range of environments is essential to determine desirable combinations.

The regulation of pollen tube growth in Douglas-fir following high doses of ionizing radiation.

Acute irradiation of Douglas-fir (Pseudotsuga menziesii [Mirb.] Franco) pollen by X-rays enhances pollen tube elongation. To determine whether this effect was due to physical damage of the pollen membranes or to metabolic processes, irradiated and control pollen were grown under conditions of anoxia. Thus, it was determined that physical damage only could be of minor importance. As parameters for metabolic processes RNA- and protein synthesis were studied. The only difference between irradiated and control pollen with respect to RNA synthesis was the time at which it started. Protein synthesis in vitro revealed that polyribosomes from irradiated pollen were more active than those from control pollen at lower concentrations. These results were confirmed by in ovo experiments with both polysomal preparations. The results indicate that X-ray irradiation is interfering with the main regulatory mechanism of pollen tube growth, which is de- and re-masking of, mainly, presynthesized mRNA.

Ultraviolet irradiation of maize (Zea Mays L.) pollen grains : I. Pollen genotype effects on kernel development.

Mature pollen grains from two single cross hybrids, Wf9 × H55 and K64 × K55, were exposed to eleven levels (0 to 6.80 erg/cm(2) × 10(5) at 0.68 intervals) of ultraviolet irradiation and then were used to pollinate their genetic source. The number and weight of the normal and shrunken (partially aborted) kernels on each ear were tabulated. In general, the number of normal kernels decreased and the number and percentage of shrunken kernels increased with increasing exposure. However, significant exposure X hybrid interactions were present indicating that the amount of change depended on the hybrid. No consistent relationship between exposure and either normal or shrunken kernel weight was apparent, but pollen source hybrid was a contributing factor. The embryo weight and coleoptile length after germination were also determined for the normal kernels. Changes in these characters by irradiation were also strongly influenced by the hybrid. These results indicate that the direction and magnitude of the changes in kernel development produced by ultraviolet are modified considerably by the genetic source of the pollen grains. Presumably, genetic variation for ultraviolet response is present and selection would be successful.

Ultraviolet irradiation of maize (Zea Mays L.) pollen grains : II. Pollen genotype effects on plant characteristics.

Mature pollen grains from two single cross (F1) hybrids, Wf9 X H55 and K64 X K55, were exposed to eleven levels (0 to 6.80 erg/cm(2) × 10(5) at 0.68 intervals) of ultraviolet irradiation and then were used to pollinate their source. Height and kernel characteristics (kernel weight, weight/100 kernels, kernel number) of individual F2 plants produced by the normal F2 kernels obtained from these pollinations were measured within each level and population. Highly significant exposure X population interactions were found for all characters, indicating that the effect of irradiation depended on the genetic source of the pollen grains. Increasing exposure increased or did not change the mean of Wf9 X H55 and decreased the mean in K64 X K55 for all characters. For coefficient of variation values, the interaction, exposure X population, was not significant for any character measured, indicating that irradiation-induced variability was unrelated to pollen source. The results indicate that pollen source strongly influenced the effect of ultraviolet irradiation on plant means but had no influence on variability.

Identification of soybean cultivars by the surface relief of the seed coat.

The relief of the outer surface of the seed coat of 16 diverse cultivars of soybeans, Glycine max (L.) Merrill, was compared on the basis of pattern, mound number and mound height in both air and water media. Significant differences among cultivars were found indicating that surface relief characteristics were cultivar-specific and could be used to describe and distinguish cultivars.

Genotypic effects on the amino acid relationships in maize (Zea mays L.) pollen and style.

The free amino acid content of the pollen grains and the style from three single cross hybrids (Wf9 x H55, Ky49 x Ky27, K64 x K55) and two inbred lines (Oh43, H55) was determined. No tyrosine was detected in the pollen grains of any genotype. Significant differences between pollen genotypes were found for aspartic acid, threonine, serine, lysine and histidine with no effect resulting from the vigor of the pollen source. No proline was found in the style of any genotype. Significant differences between style genotypes were obtained for threonine, serine, glutamic acid, leucine, tyrosine, ethanolanine, α aminobutyric acid and histidine with a relationship between vigor of the style genotype present for tyrosine, ethanolanine and α aminobutyric acid. The relationship between the pollen and style level for each amino acid as influenced by genotype was analyzed. A significant negative correlation was found only for threonine. Apparently, a complementary relationship between the pollen and style exists for some amino acids. Proline and tyrosine are available only from the pollen and style respectively. Threonine levels are balanced with varying contributions from both pollen and style depending on the genotype.