Pollen Mixture Research Articles

Evaluation of serum IgG4 antibodies specific to grass pollen allergen components in the follow up of allergic patients undergoing subcutaneous and sublingual immunotherapy

Background A number of reports suggest that induction of IgG ‘blocking antibodies’ may be important for successful allergen immunotherapy. Nevertheless, a significant increase in specific IgG and IgG4 antibodies has not been consistently demonstrated for sublingual immunotherapy (SLIT). Methods The present observation included three groups of grass pollen allergic patients all submitted to three different allergen immunotherapeutic regimens in an open, non-placebo controlled clinical study: (i) 16 patients underwent a modified ‘cluster’ regimen of weekly injections of a standardized aluminium-absorbed Phleum pratense extract for 5 weeks, followed by 3 weeks of maintenance injections. (ii) Fifteen patients were treated with standardized timothy grass pollen-allergen oral vaccine. In the first session of a SLIT protocol without up-dosing, each patient received 2.4 ml of sublingual vaccine containing about 57 μg of Phl p 5 and received a maintenance dose of 24 μg of Phl p 5 once a day for 120 days. (iii) Fourteen subjects were treated with a standardized allergen extract containing 5-grass pollen mixture; a SLIT protocol was performed without up-dosing, administering a dose corresponding to about 10.0 μg/ml grass-pollen Group 5 and a maintenance dose of 4 μg of grass-pollen Group 5 once a day for 135 days. Patients’ sera were characterized in detail by determining IgG4 antibodies to rPhl p 1, 2, 5, 6, 7, 11, 12 and nPhl p 4 and eosinophil cationic protein before the start of immunotherapy and during the peak of pollen season. Results No relevant systemic side effects were registered in patients treated with the modified cluster subcutaneous immunotherapy (SCIT) protocol and the two SLIT protocols without build-up phase. After SCIT all patients had high titres of serum allergen-specific IgG4 antibodies. High-dose SLIT led to an IgG4 increase comprising 25% of the SCIT level, while low-dose SLIT increased to 4% of the SCIT. Furthermore, the increase of specific IgG antibodies corresponds to a decrease of serum ECP during allergen exposure. Conclusions These preliminary data seem to indicate that: (i) pre-seasonal high-dose SLIT protocol without build-up phase is safe and well-tolerated by allergic patients; (ii) compared to IgG4 levels induced by SCIT, only a high-dose SLIT regimen results in an appreciable serum specific IgG4 increase.

Mating interactions between coexisting dipoloid, triploid and tetraploid cytotypes ofHieracium Echioides (Asteraceae)

Experimental crosses between diploids, triploids and tetraploids ofHieracium echioides were made to examine mating interactions. Specifically, cytotype diversity in progeny from experimental crosses, intercytotype pollen competition as a reproductive barrier between diploids and tetraploids, and differences in seed set between intra- and intercytotype crosses were studied. Only diploids were found in progeny from 2x × 2x crosses. The other types of crosses yielded more than one cytotype in progeny, but one cytotype predominated in each cross type: diploids (92%) in 2x × 3x crosses, tetraploids (88%) in 3x × 2x crosses, triploids (96%) in 2x × 4x crosses, triploids (90%) in 4x × 2x crosses, tetraploids (60%) in 3x × 3x crosses, pentaploids (56%) in 3x × 4x crosses, triploids (80%) in 4x × 3x crosses and tetraploids (88%) in 4x × 4x crosses. No aneuploids have been detected among karyologically analyzed plants. Unreduced egg cell production was detected in triploids and tetraploids, but formation of unreduced pollen was recorded only in two cases in triploids. Triploid plants produced x, 2x and 3x gametes: in male gametes x (92%) gametes predominated whereas in female gametes 3x (88%) gametes predominated. Cytotype diversity in progeny from crosses where diploids and tetraploids were pollinated by mixture of pollen from diploid and tetraploid plants suggested intercytotype pollen competition to serve as a prezygotic reproductive barrier. No statistically significant difference in seed set obtained from intra- and intercytotype crosses between diploids and tetraploids was observed, suggesting the absence of postzygotic reproductive barriers among cytotypes.

Explaining Outcrossing Rate in Campanulastrum americanum (Campanulaceae): Geitonogamy and Cryptic Self‐Incompatibility

A flexible mating system may enable self‐compatible plants to prevent self‐fertilization under certain circumstances. Campanulastrum americanum is a self‐compatible, protandrous herb. Although within‐plant pollen transfer is likely and self pollen can produce a full set of seeds, selfing in natural populations is rare. We investigated explanations for the high outcrossing rate. One possibility was that self pollen contacts the stigma rarely. We surveyed floral displays in nature to gauge the potential for within‐plant pollen transfer. Floral displays in nature are large enough to enable frequent geitonogamous pollinator visits and subsequent self‐pollination. Alternatively, the high outcrossing rate could result from cryptic self‐incompatibility, a mechanism that favors outcross pollen over self pollen. To determine whether outcross pollen has a seed‐siring advantage over self pollen, we pollinated maternal plants with equal mixtures of self and outcross pollen. Genotyping the offspring revealed that outcross pollen sired significantly more seeds than self pollen. We explored whether differential growth rates of self and outcross pollen tubes produce cryptic self‐incompatibility. Growth rates did not differ, indicating that cryptic self‐incompatibility occurs by some other mechanism. Cryptic self‐incompatibility enables C. americanum to reduce inbreeding when outcross pollen is present yet ensure reproduction when only self pollen is available.

Effectiveness of new agri-environment schemes in providing foraging resources for bumblebees in intensively farmed landscapes

Intensive farming has contributed to the serious declines in abundance and geographic range suffered by several bumblebee species in Europe and North America. Recent UK agri-environmental policy aims to conserve and restore bumblebee populations by providing foraging habitats on arable field margins. We examined the effectiveness of strategies to achieve this, including sowing seed mixtures of (1) tussocky grass species, (2) wildflowers and (3) pollen- and nectar-rich plants. These were compared to conventionally managed cereal crops. Sampling was undertaken in 32 10 × 10 km squares throughout England, each containing a sample of the different field margin types. Bumblebee abundance in July and August was significantly higher on pollen and nectar margins (86 ± 14 bees per 100 m) compared with wildflower margins (43 ± 14), mature grass margins (6 ± 14) and recently sown grass margins (8 ± 4). Bees were virtually absent from the cereal crop (0.2 ± 0.1). Bumblebee species richness was significantly higher on margins sown with either wildflowers or the pollen and nectar mix. There was evidence that richness of the bumblebee assemblage at the 10 × 10 km square scale was positively correlated with land use heterogeneity, the proportion of grassland, and the abundance and richness of dicotyledon flowers. The abundance of long-tongued bees per margin was explained by the number of pollen and nectar agreements per 10 × 10 km square, together with flower abundance. Future research is required to determine the quantity and location of foraging habitat required to sustain bumblebee populations at the landscape scale.

Nesting biology, seasonality, and flower hosts of Epicharis nigrita (Friese, 1900) (Hymenoptera: Apidae: Centridini), with a comparative analysis for the genus

Nesting biology and foraging behaviour of Epicharis nigrita were studied in a cerrado ecosystem in São Paulo State, Brazil. Epicharis nigrita is a univoltine and seasonal bee species that collects pollen and floral oils from Byrsonima (Malpighiaceae) flowers. Activity of adults was observed on nesting sites and on flowers from October to December. Epicharis nigrita builds nests in aggregations in sandy soil. A nest consists of a single tunnel, which leads to a single urn-shaped cell. Cells are provisioned with a mixture of pollen and floral oils from Byrsonima. Cleptoparasitic species of the genera Rhathymus, Mesoplia, and Tetraonyx were active at the nesting sites. The biology of E. nigrita is compared to that of other species in the genus. Resumo A biologia da nidificação e o comportamento de forrageamento de Epicharis nigrita foram estudados em um ecossistema de cerrado no estado de São Paulo, Brasil. Epicharis nigrita é uma espécie de abelha univoltina e sazonal, que coleta pólen e óleos de flores de Byrsonima (Malpighiaceae). Atividade dos adultos foi observada na área de nidificação e nas flores entre outubro e dezembro. Epicharis nigrita constrói ninhos em agregações em solo arenoso. O ninho consiste de um único canal que leva a uma única célula isolada, com forma de urna. Células são aprovisionadas com uma mistura de pólen e óleos florais de Byrsonima. Espécies de cleptoparasitos dos gêneros Rhathymus, Mesoplia e Tetraonyx foram encontradas em atividade nas áreas de nidificação. A biologia de E. nigrita é comparada a de outras espécies no gênero.

A Novel Method to Quantify Transport of Self- and Cross-pollen by Bees in Blueberry Plantings

Blueberry species (Vaccinium section Cyanococcus) benefit from cross-pollination. Outcrossing increases fruit set, berry size, and ripening rate. Although knowledge of pollen dispersal is essential for maximizing cross-pollination and achieving optimal planting designs, this process has not been quantified previously in blueberry plantings. A novel method was developed to estimate the proportion of self- and cross-pollen transported by blueberry pollinators. The proposed technique requires a consistent difference in pollen size between two cultivars to predict the composition of a pollen mixture based on frequency distributions of pollen diameter. Vaccinium ashei Reade `Brightwell' and `Climax' were chosen for this study because they produce pollen tetrads of different size. Tetrad diameter and number were analyzed with a particle counter. The technique was validated by predicting the proportion of `Brightwell' in pollen mixtures where the cultivar composition was known, and predicted and actual values were linearly correlated (r = 0.995, P < 0.0001). The technique was then applied to pollen samples extracted from the bodies of pollinators that were collected in a mixed `Brightwell' and `Climax' blueberry plot. Numbers of blueberry tetrads extracted per bumblebee (Bombus spp.) averaged 4595 and 797 in 2003 and 2004, respectively, which was considered adequate to make accurate predictions based on frequency distributions of tetrad diameter. The proportion of `Brightwell' pollen carried by bumblebees changed with the phenology of the crop following an expected pattern, indicating that the method performed well under field conditions. This technique could potentially be used to quantify the likelihood for outcrossing and establish the effect of cultivar arrangements on pollen dispersion, as well as to examine pollen collection and manipulation, and cultivar preference by bees.

Apple pollen as a supplemental food for the western flower thrips, Frankliniella occidentalis: response of individuals and populations

AbstractExperiments were performed to investigate the influence of apple pollen, plant diet, and relative humidity on the individual life‐history traits and on the population growth of the western flower thrips, Frankliniella occidentalis (Pergande) (Thysanoptera: Thripidae). In experiments with individual thrips, availability of bean pods plus a mixture of apple pollen and lycopodium shortened larval development time, and hence time from egg to adult, compared to bean pods alone. Similarly, the total number of eggs laid and the mean number of eggs laid per female per day were greater in the presence of pollen plus bean pods than on bean pods alone. Diet did not affect survival or length of the pre‐oviposition and oviposition periods. A diet including bean pods plus pollen shortened the generation time and population‐doubling time, and increased the net reproductive rate and the intrinsic rate of increase, compared to bean pods alone. In experiments on populations, growth was measured with different amounts of pollen on bean pods under two relative humidities, ca. 38% and 66%, and separately on two bean substrates, pods or leaves, at ca. 45% r.h. The presence or amount of pollen had no effect on population growth regardless of the other variables. Greater population growth occurred under the higher relative humidity regardless of substrate. Population growth was greater on bean pods than on bean leaves. Despite reports on the nutritional benefit of pollen for F. occidentalis, this benefit may be affected by pollen type, host plant, and other factors. In situations in which pollen has little influence on the growth of F. occidentalis populations, pollen that benefits a thrips predator could be used in an integrated management plan for controlling thrips.

Production of wheat doubled haploids (Triticum aestivumL.) by wheat × maize crosses using colchicine enriched medium for embryo regeneration

The effect of colchicine enriched culture media on embryo regeneration and the production of doubled haploid wheat plants in vitro were examined using two regeneration media enriched with 300 and 900 mg/ colchicine respectively and the results were compared with results from plants treated with colchicine after regeneration. Four German winter wheat varieties were pollinated with a pollen mixture collected from two sweet corn hybrids. The number of pollinated florets, caryopses, haploid embryos and regenerated plantlets were scored. In total 14,000 pollinated wheat florets produced 10,879 caryopses from which 2,704 embryos were excised; 1,288 embryos regenerated to plants and 958 plants survived till maturity. The regeneration of embryos to plants was influenced by the wheat varieties, the colchicine treatment and colchicine concentration. The percentage of doubled haploid plants varied depending on chromosome doubling technique, colchicine concentration and wheat variety. Plants were cultured till ripeni...

Pollen competition among two species of Senecio (Asteraceae) that form a hybrid zone on Mt. Etna, Sicily

Hybridization between interfertile, sympatric or parapatric, plant species can be reduced significantly by conspecific pollen advantage (CPA), whereby conspecific pollen has an advantage over heterospecific pollen in terms of ovule fertilization. We examined CPA in two interfertile species of Senecio, S. aethnensis, and S. chrysanthemifolius (Asteraceae), which form a hybrid zone on Mt. Etna, Sicily. Individuals of both species were pollinated with pollen mixtures containing 0, 25, 50, 75, or 100% heterospecific pollen, and offspring were genotyped to determine if they were products of conspecific or heterospecific pollen fertilizing the ovules. The mean proportion of hybrid offspring produced on S. aethnensis plants was not significantly different to that expected based on the proportion of heterospecific pollen applied to the flower head. However, S. chrysanthemifolius mother plants showed moderate CPA, with the proportion of hybrid offspring significantly less than expected. Seed set or seed germination was not reduced, hence the CPA found for S. chrysanthemifolius acts before ovule fertilization. The consequences of asymmetry in CPA on the reproductive isolation of S. aethnensis are briefly discussed, along with other mechanisms that may play a role in the maintenance of the hybrid zone on Mt. Etna.

Post-pollination mechanisms promoting outcrossing in a self-fertile conifer,Thuja plicata(Cupressaceae)

In conifers, polyembryony (multiple embryos within an ovule) may decrease the number of seeds lost to random embryo abortion, and (or) increase the proportion of outcrossed seeds if outcrossed embryos out-compete selfed ones. Western redcedar (Thuja plicata Don ex D. Donn, Cupressaceae) is a conifer with a mixed (selfed and outcrossed) mating system and high self-fertility with simple (archegonial) polyembryony. To test whether polyembryony can decrease seed abortion or the proportion of selfed seedlings, we conducted controlled pollinations in a seed orchard in southwestern British Columbia. Four trees received a total of 48 pollination treatments consisting of self, outcross, or mixtures of self and outcross pollen. Enzyme electrophoresis identified selfed seeds in the mixed pollen treatments. Reduction in the proportion of filled seeds (seed set) owing to selfing was approximately 30% for three of the trees and 93% for the fourth. Following mixed pollinations we did not observe an increase in seed set attributable to polyembryony. However, when trees received high ratios of self-pollen they produced fewer selfed seedlings than expected, suggesting embryo competition. The consequences of these results on the mating system of western redcedar are discussed.Key words: conifer, Cupressaceae, embryonic lethals, inbreeding depression, polyembryony, Thuja plicata.

Male-sterility induced by gamma-ray irradiation of African nightshade (Solanum nigrum L. ssp. villosum) seed

SummaryThe leaf yields of vegetables belonging to the Solanum nigrum complex are limited by prolific early flowering and berry set. Source-sink limitations and imbalances occur after anthesis, with dry matter partitioning directed more to pollen, seed and fruit formation and development. Each of these processes is associated with high respiratory costs, in competition with leaf expansion and productivity. To use male-sterility to redistribute biological biomass towards greater economic leaf yield, a range of mutants inducible by irradiation of seed with gamma-rays was investigated. On the basis of overall plant development from germination, seedling survival, production of M2 selfed-seed and the frequency of male-sterile mutants, 100 Gy of gamma-rays was determined to be the optimum dose. Four male-sterile mutant types were isolated during the Spring-Summer season from the M2 screen: (i) an acetocarmine-stained non-viable pollen type which stained black with potassium iodide solution (T-1); (ii) a defective pollen type not stainable with acetocarmine (T-2); (iii) a pollen-less type with defective anthers (T-3); and (iv) an extremely low pollen-producing type (T-4). An intermediate type (T-1/2) had a mixture of acetocarmine stainable and defective non-stainable pollen. All T-1, and some T-3 mutants were partially restored and set berries with selfed-seed, while T-1/2 set non-seeded berries in the Autumn-Winter season. Eliminating the reproductive function and subsequently fruits, which are the major sink organs of the plant, is expected to enable the male-sterile mutants isolated in this study to use the biomass no longer allocated to pollen (and eventually to berry and seed production), for extra leaf production.

Immunophenotyping of the cutaneous cellular infiltrate after atopy patch testing in cats with atopic dermatitis.

Cats with spontaneously occurring atopic dermatitis have clinical and immunocytochemical characteristics compatible with these in humans with atopic dermatitis (AD). The atopy patch test (APT) has proven to be a valuable tool in elucidating the disease process in humans. Additionally, the APT is very specific and bypasses the problem of conflicting results due to differences in chronicity of lesions of AD patients. We adapted the APT for use in cats to explore the suitability of the APT as a tool to study the onset of allergic inflammation in cats with atopic dermatitis. APT were performed in AD cats (n = 6) and healthy cats (n = 10). All cats were patch tested with two allergens in three different dilutions and a diluent control. The allergens for the APT were selected from positive intradermal test and /or prick test results and consisted of: Dermatophagoides farinae, D. pteronyssinus, Tyrophagus putrescentiae, and a grass pollen mixture. APT were read after 10, 24 and 48 h, and punch biopsies for immunohistochemical evaluation were collected at these time points. Macroscopically positive APT reactions were observed in three out of six cats at 24 and/or 48 h with allergen concentrations of 25,000 and 100,000 NU/ml. Reactions were not observed at negative control sites and neither in control animals. A significantly increased number of IL-4+, CD4+, CD3+, MHC class II+ and CD1a+ cells was found in one AD cat with positive APT reactions. Five out of six AD cats had significantly increased IL-4+ T cell numbers at 24 and/or 48 h. Our data indicate that in cats, macroscopically positive patch test reactions can be induced, which have a cellular infiltrate similar to that in lesional skin. We found a high specificity and a macroscopically positive APT reaction in half of the cats, which is similar to what is seen in humans. Hence, the APT in cats might be a useful tool in studying the immunopathogenesis of feline atopic dermatitis.

Pollen–pollen interactions in Pinus sylvestris

Direct pollen–pollen interactions can influence pollen fertilization ability when pollen from different donors and origins germinate on the same flower. In this study, in vitro germination tests were used to study direct pollen–pollen interactions in Scots pine (Pinus sylvestris L.). Pollen from southern (S, latitude 61° N) and northern (N, latitude 68° N) origins was germinated separately and in pairs at two temperatures (16 and 20°C), and pollen germination percentages and pollen tube lengths of the samples were analysed. The observed pollen performances of the two-donor pollen mixtures were compared with the mean performances of the pure pollen samples germinated in isolation. The significant difference between the observed and expected pollen performances indicated pollen–pollen interactions. Among S×S mixtures, only negative pollen–pollen interactions (= interference) were detected, while only positive interactions were found among N×N mixtures. Both types of interaction were substantially more frequent at the lower temperature. In general, direct pollen–pollen interactions during in vitro germination were rather infrequent and are not likely to have substantial influence on fertilization abilities in vivo in seed orchards or in natural forest stands of Scots pine. However, direct pollen–pollen interactions can be more pronounced among certain genotypes, which should be considered in artificial crossing experiments using pollen mixtures.

Effect of pollinator on haploid production in durum wheat crossed with maize and pearl millet

AbstractThe aim of this work was to analyse the influence of the male parent on the production of embryos and haploid plants in durum wheat crossed with maize and pearl millet, to find a proper trait to identify the most efficient pollinators and to evaluate the mixtures of pollen. Two genotypes of durum wheat, low and high responding, were crossed with eight pollen samples: (i) three maize hybrids, (ii) three pearl millet inbred lines, (iii) a mixture of maize pollen and (iv) another mixture of pearl millet pollen. No significant differences on embryos and haploid plant production were observed among the four samples of maize pollen, but there were clear genotypic differences for the production of haploids between genotypes of pearl millet. The best pearl millet genotype produced significantly more haploid plants than the other two and the mixture of pollen. There was no correlation between the production of embryos and haploid plants. Therefore, the production of haploid plants must be the criterion to identify superior pollinators. In addition, a mixture of pollen is inappropriate except when using genotypes previously identified as good pollinators.

Profile of pollen allergy in hungarian children having respiratory allergic diseases between 1992 and 2000

Rationale Between 1992 and 2000 allergy skin prick tests (SPT) were performed on 2,124 children suspected of having respiratory allergic diseases. Previous studies showed that grass pollen was the most frequent allergen (32.8%), while ragweed allergy occurred in 24% of children. Methods In this study children who produced a positive reaction to tree or weed pollen mixtures were investigated by SPT to other aero-allergen pollens (Bencard allergens), including tree pollens (471 children) and weed pollens (476 children). 22% of the tested children reacted to at least one tree pollen. Results Between 1992 and 2000 the frequency of reactivity to ash pollen increased from 3% to 11%, and to birch pollen, from 3.6% to 10.7%. In 2000, all trees produced a positive skin reaction in at least 7% of the 2,124 children. The prevalence of allergy to maize and rye was constant (13.7%) during the investigated years, whereas reactivity increased from 6% to 16%, almost always (254 cases) associated with ragweed allergy. 22% of the investigated children were allergic to at least one tree pollen, most commonly ash (11%) and birch (10.7%). Conclusions The clinical importance of tree pollen allergy in Hungary is less than in northern Europe, but weed allergy is rapidly increasing related to mugwort and ragweed.

Assimilation of carbon and nitrogen from pollen and nectar by a predaceous larva and its effects on growth and development

Abstract. 1. Predaceous insects may benefit from feeding on non‐prey foods, such as pollen, nectar, and honeydew, because they can provide nutrients that help maintain metabolism and enhance overall nutrient intake. Yet, the extent to which predaceous insects can assimilate non‐prey food and the importance of diet mixing during particular life history stages is poorly understood. In this study the relative contribution of an omnivorous diet to the growth and survivorship of a predaceous larva was tested in a hypothetical situation in which nutritionally optimal prey was not available. The study system comprised a predaceous larva (second‐ and third‐instar larvae of the green lacewing Chrysoperla carnea), nutritionally poor prey (larvae of Drosophila melanogaster), and non‐prey food (pollen suspension, a mixture of bee pollen and artificial nectar (1 M sucrose solution)). Chrysoperla carnea larvae in the mixed diet treatment were provided with both Drosophila larvae and pollen suspension, while those reared on the prey and non‐prey diet treatments received only Drosophila larvae or pollen suspension respectively.2. The inclusion of pollen and sucrose in their diet enhanced the growth of C. carnea larvae. Second instars reared on the mixed diet developed significantly faster than their cohorts reared on the prey diet, however third instars reared on the mixed diet did not develop faster than their cohorts reared on the prey diet. Larvae reared on the mixed diet became larger adults than did those reared on either the prey or non‐prey diets. Third instars reared on the non‐prey diet completed their development while second instars in the non‐prey diet treatment failed to pupate.3. Stable isotope analysis indicated that the larvae obtained most of their carbon (55–73%) and nitrogen (71–73%) from Drosophila but acquired only a minor amount of carbon (2–5%) and nitrogen (3–11%) from pollen. Larvae reared on the mixed and non‐prey diets acquired a relatively significant amount of carbon (23–51%) from sucrose.4. A model, which included a novel fractionation factor to account for the isotopic effect of metamorphosis, was developed to explain the proportion of larval growth attributable to each diet item. It explained the adult δ13C values to within 0.2‰ and adult δ15N values to within 0.7‰ in all treatments.5. Adults fed 15N‐labelled pollen as larvae retained the 15N signal of the pollen as adults.6. The collective results of this study support the view that, despite their dependence on prey arthropods to obtain most of their dietary nitrogen, omnivorous lacewing larvae can enhance their growth and development by supplementing their diets with alternative non‐prey food resources. This finding is consistent with the notion that omnivory has evolved as a feeding strategy to acquire both additional nitrogen as well as trace nutrients.

Maize ROP2 GTPase provides a competitive advantage to the male gametophyte.

Rop GTPases have been implicated in the regulation of plant signal transduction and cell morphogenesis. To explore ROP2 function in maize, we isolated five Mutator transposon insertions (rop2::Mu alleles). Transmission frequency through the male gametophyte, but not the female, was lower than expected in three of the rop2::Mu mutants. These three alleles formed an allelic series on the basis of the relative transmission rate of each when crossed as trans-heterozygotes. A dramatic reduction in the level of ROP2-mRNA in pollen was associated with the three alleles causing a transmission defect, whereas a rop2::Mu allele that did not result in a defect had wild-type transcript levels, thus confirming that mutation of rop2 causes the mutant phenotype. These data strongly support a role for rop2 in male gametophyte function, perhaps surprisingly, given the expression in pollen of the nearly identical duplicate gene rop9. However, the transmission defect was apparent only when a rop2::Mu heterozygote was used as the pollen donor or when a mixture of wild-type and homozygous mutant pollen was used. Thus, mutant pollen is at a competitive disadvantage compared to wild-type pollen, although mutant pollen grains lacked an obvious cellular defect. Our data demonstrate the importance in vivo of a specific Rop, rop2, in the male gametophyte.

Desempenho de híbridos de linhagens parcialmente endogâmicas de milho em regiões dos estados de Roraima e Minas Gerais

Entre as alternativas de tipos de híbridos de milho (Zea mays L.), os que envolvem linhagens parcialmente endogâmicas (LPE) S2 possuem a vantagem de maior rapidez na obtenção, se comparados com linhagens de endogamia completa. Essas LPE S2 podem ser obtidas a partir de qualquer tipo de população, porém, uma boa opção seria aquelas derivadas de híbridos simples comerciais, que associam produtividade e grande proporção de locos segregantes. Com esse intuito, o presente trabalho foi conduzido visando à avaliação de híbridos de LPE S2 derivados de três híbridos simples comerciais. Para obtenção dos híbridos, foram selecionados 30 LPE S2 de três populações distintas das cultivares híbridas comerciais: AG-9012, C-333B e Z-8392. Os cruzamentos foram realizados em esquema de dialelo circulante, em que cada LPE S2 de uma população foi cruzada com outras três LPE S2 de outra população. Para os cruzamentos, as LPE S2 foram semeadas em linha com dez metros cada uma. No aparecimento das primeiras espigas, as mesmas foram protegidas e, por ocasião da polinização, uma mistura de pólen de cada LPE S2 foi utilizada para polinizar pelo menos dez plantas de uma outra população LPE S2. Os híbridos obtidos foram avaliados em Boa Vista, Roraima e em Lavras, Minas Gerais, utilizando-se o delineamento látice simples 12x12, envolvendo os 135 híbridos LPE S2 obtidos e mais nove testemunhas, sendo elas as gerações F1 dos híbridos simples AG-9012, C-333B e Z-8392, um híbrido duplo (C 435) e cinco outros híbridos intervarietais. A parcela experimental foi constituída por uma linha de três metros de comprimento, espaçada de 90 cm entre linhas e permanecendo um total de cinco plantas por metro linear após o desbaste. As seguintes variáveis foram avaliadas: peso de espiga despalhada (PESP), altura de planta (ALTP) e altura de espiga (ALTE). Para a PESP, 81% dos híbridos S2 foram superiores às médias das testemunhas. Observou-se que 17% dos híbridos de LPE S2 tiveram desempenho superior ao híbrido simples C-333B C (10,76 t/ha) e 46% apresentaram desempenho superior à testemunha C-435 (9,56 t/ha), um híbrido duplo amplamente utilizado nos dois estados. Para ALTP e ALTE, os resultados foram semelhantes a PESP, salientado que o contraste H vs T foi não-significativo, inferindo-se que os híbridos S2 e as testemunhas apresentaram, em média, as mesmas ALTP e ALTE. Com esse fato, evidencia-se que os híbridos LPE S2 são semelhantes aos híbridos comerciais e mostra o potencial da utilização desse tipo de híbridos no Brasil, que pode substituir com vantagens alguns híbridos comerciais disponíveis no mercado.

Pollen from Different Olive Tree Cultivars Contains Varying Amounts of the Major Allergen Ole e 1

Background: Commercial olive pollen from uncertain cultivar origin is the common material used for clinical and biological studies. We aimed to assess the putative heterogeneity of olive cultivars with regard to the presence of the major pollen allergen Ole e 1 and to determine whether these differences have clinical relevance. Methods: The Ole e 1 content of several cultivars was determined by immunoblotting and ultrastructural immunocytochemistry and compared to that of a commercially available olive pollen extract designed for diagnosis. Reverse transcription-polymerase chain reaction analysis of Ole e 1 transcripts was also performed. Crude protein extracts were used to carry out skin prick tests (SPTs) on 30 allergic patients in order to evaluate the clinical importance of such differences. Results: Ole e 1 was present in all cultivars, although significant quantitative differences were detected. Ole e 1 transcripts positively correlated with the amount of the allergen. Significant variations in the average reactivity of allergic patients to SPTs were observed depending on the cultivar considered. Conclusions: The presence of the Ole e 1 allergen in all the cultivars suggests that this allergen may play an essential biological role. The expression of the allergen is controlled at the transcriptional level. The significant differences in the Ole e 1 content are likely responsible for the different average reactivity exhibited by patients to the cultivars studied, although the role of other allergens cannot be excluded. Our results suggest that the use of the commercial pollen mixtures currently available may lead to mistakes in allergy diagnosis and to limited success in immunotherapy. Therefore, further standardization is strongly recommended.

Characterization of six microsatellite loci in Echium vulgare (Boraginaceae)

Abstract Echium vulgare is a tetraploid plant with a very low selfing rate in the field. We suspect that cryptic self incompatibility plays a role in this species. In order to show lower success of self pollen/selfed embryos, after pollination with a mixture of self and outcross pollen, a paternity analysis has to be done. For the purpose of such analysis we developed microsatellites in E. vulgare. In this study, we report on six microsatellite loci which are easy to score, polymorphic, with a number of alleles per locus ranging from two to eight and, therefore, suitable for paternity analysis.