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PubMed1995

Multiple origins of the yucca-yucca moth association.

The association of species of yucca and their pollinating moths is considered one of the two classic cases of obligate mutualism between floral hosts and their pollinators. The system involves the active collection of pollen by females of two prodoxid moth genera and the subsequent purposeful placement of the pollen on conspecific stigmas of species of Yucca. Yuccas essentially depend on the moths for pollination and the moths require Yucca ovaries for oviposition. Because of the specificity involved, it has been assumed that the association arose once, although it has been suggested that within the prodoxid moths as a whole, pollinators have arisen from seed predators more than once. We show, by using phylogenies generated from three molecular data sets, that the supposed restriction of the yucca moths and their allies to the Agavaceae is an artifact caused by an incorrect circumscription of this family. In addition we provide evidence that Yucca is not monophyletic, leading to the conclusion that the modern Yucca-yucca moth relationship developed independently more than once by colonization of a new host.

Animals↗
PubMed1997

Pronounced cytoplasmic pH gradients are not required for tip growth in plant and fungal cells.

The existence of pronounced cytoplasmic pH gradients within the apices of tip-growing cells, and the role of cytoplasmic pH in regulating tip growth, were investigated in three different cell types: vegetative hyphae of Neurospora crassa; pollen tubes of Agapanthus umbellatus; and rhizoids of Dryopteris affinis gametophytes. Examination of cytoplasmic pH in growing cells was performed by simultaneous, dual emission confocal ratio imaging of the pH-sensitive probe carboxy SNARF-1. Considerable attention was paid to the fine tuning of dye loading and imaging parameters to minimise cellular perturbation and assess the extent of dye partitioning into organelles. With optimal conditions, cytoplasmic pH was measured routinely with a precision of between +/-0.03 and +/-0.06 of a pH unit and a spatial resolution of 2.3 microm2. Based on in vitro calibration, estimated values of mean cytoplasmic pH for cells loaded with dye-ester were between 7.15 and 7.25 for the three cell types. After pressure injecting Neurospora hyphae with dextran-conjugated dye, however, the mean cytoplasmic pH was estimated to be 7.57. Dextran dyes are believed to give a better estimate of cytoplasmic pH because of their superior localisation and retention within the cytosol. No significant cytoplasmic pH gradient (delta pH of >0.1 unit) was observed within the apical 50 microm in growing cells of any of the three cell types. Acidification or alkalinisation of the cytoplasm in Neurospora hyphae, using a cell permeant weak acid (propionic acid at pH 7.0) or weak base (trimethylamine at pH 8.0), slowed down but did not abolish growth. However, similar manipulation of the cytoplasmic pH of Agapanthus pollen tubes and Dryopteris rhizoids completely inhibited growth. Modification of external pH affected the growth pattern of all cell types. In hyphae and pollen tubes, changes in external pH were found to have a small transient effect on cytoplasmic pH but the cells rapidly readjusted towards their original pH. Our results suggest that pronounced longitudinal gradients in cytoplasmic pH are not essential for the regulation of tip growth.

Benzopyrans↗
PubMed2000

Ontogenetic events in androgenesis of Brazilian barley genotypes.

This paper describes a simple procedure for obtention of barley (Hordeum vulgare L.) doubled haploid plants from Brazilian hybrid genotypes. Anatomical and histological examinations showed the reversion of barley pollen to an sporophytic mode of development. A sequence of mitosis led to the formation of multicellular pollen grains. Regeneration of plants occurred either by direct embryogenesis or callus formation followed by differentiation through direct embryogenesis or organogenesis. Plants were formed in the same medium used for induction dispensing an additional regeneration step. This procedure makes doubled haploid production simpler and faster. Plantlets were transferred to another medium for rooting and after that planted in pots with vermiculite and nutrient solution.

Journal Article↗
PubMed2002

Sexual interference of the floral kind.

Floral hermaphroditism results in conflicts and compromise in the parental roles of plants during pollination and mating. A potential cost of hermaphroditism is sexual interference between maternal and paternal functions resulting in gamete wastage and reduced fitness. Sexual interference may or may not be associated with self-pollination. In cases where self-pollination occurs, ovule or pollen discounting may reduce mating opportunities. Here I describe forms of sexual interference in flowering plants, distinguishing whether physical or biochemical interactions are involved and whether fitness costs associated with gamete wastage arise from intra-floral versus inter-floral processes. I review the limited experimental evidence for interference between sex functions and evaluate the hypothesis that some floral adaptations usually interpreted as anti-selfing mechanisms may serve an alternative function in reducing mating costs arising from this form of sexual conflict.

Disorders of Sex Development↗
PubMed2001

Comparative floral development of Mir-grown and ethylene-treated, earth-grown Super Dwarf wheat.

To study plant growth in microgravity, we grew Super Dwarf wheat (Triticum aestivum L.) in the Svet growth chamber onboard the orbiting Russian space station, Mir, and in identical ground control units at the Institute of BioMedical Problems in Moscow, Russia. Seedling emergence was 56% and 73% in the two root-module compartments on Mir and 75% and 90% on earth. Growth was vigorous (produced ca. 1 kg dry mass), and individual plants produced 5 to 8 tillers on Mir compared with 3 to 5 on earth-grown controls. Upon harvest in space and return to earth, however, all inflorescences of the flight-grown plants were sterile. To ascertain if Super Dwarf wheat responded to the 1.1 to 1.7 micromoles mol-1 atmospheric levels of ethylene measured on the Mir prior to and during flowering, plants on earth were exposed to 0, 1, 3, 10, and 20 micromoles mol-1 of ethylene gas and 1200 micromoles mol-1 CO2 from 7 d after emergence to maturity. As in our Mir wheat, plant height, awn length, and the flag leaf were significantly shorter in the ethylene-exposed plants than in controls; inflorescences also exhibited 100% sterility. Scanning-electron-microscopic (SEM) examination of florets from Mir-grown and ethylene-treated, earth-grown plants showed that development ceased prior to anthesis, and the anthers did not dehisce. Laser scanning confocal microscopic (LSCM) examination of pollen grains from Mir and ethylene-treated plants on earth exhibited zero, one, and occasionally two, but rarely three nuclei; pollen produced in the absence of ethylene was always trinucleate, the normal condition. The scarcity of trinucleate pollen, abrupt cessation of floret development prior to anthesis, and excess tillering in wheat plants on Mir and in ethylene-containing atmospheres on earth build a strong case for the ethylene on Mir as the agent for the induced male sterility and other symptoms, rather than microgravity.

Carbon Dioxide↗
PubMed2004

Biology of three species of Agistemus (Acari: Stigmaeidae): life table parameters using eggs of Panonychus citri or pollen of Malephora crocea as food.

The biology and life table parameters of Agistemus industani Gonzalez, A. cyprius Gonzalez, and A. floridanus Gonzalez (Acari: Stigmaeidae) were studied under laboratory conditions using two food sources: Panonychus citri (McGregor) eggs or ice plant, Malephora crocea (Jacquin) Schwantes pollen at 25 degrees C. The larval, protonymph, deutonymph, and adult stages of A. industani fed on citrus red mite eggs. All active stages of A. industani, except the larva, fed on all P. citri stages and the larval stage could not feed on P. citri adults. All immature stages of A. industani fed on M. crocea pollen. Agistemus cyprius larvae fed on P. citri eggs and larvae or ice plant pollen. The nymphal stages fed on P. citri eggs, larvae, and protonymphs but not deutonymphs or adults while A. cyprius deutonymphs and adults fed on all P. citri stages. Adult and nymphal stages of A. cyprius fed on ice plant pollen and successfully completed their development while A. floridanus did not. Agistemus floridanus larvae fed only on P. citri eggs, while the other stages fed on P. citri eggs, larvae, and protonymphs. The developmental times from egg to adult for A. industani and A. cyprius when fed M. crocea pollen were 11.3 and 13.4 days, respectively. Agistemus floridanus was unable to complete its life cycle on a diet of only M. crocea pollen. Agistemus industani, A. cyprius, and A. floridanus completed development from egg to adult in 11.7, 13.8, and 10.8 days, respectively, when fed P. citri eggs. The intrinsic rate of increase (r(m)) values for A. cyprius and A. industani were 0.0311 and 0.1201 per day on the pollen diet. The net reproductive rate (Ro) was 3.58 for A. cyprius and 10.07 for A. industani with generation times (T) of 45.2 and 35.1 days, respectively, on the ice plant pollen diet. The r(m) values for A. cyprius, A. floridanus, and A. industani on the P. citri egg only diet were: 0.0562, 0.1001, and 0.1031 per day, respectively. The Ro values for each species fed P. citri eggs only were: 6.36, 7.90, and 18.70 for A. cyprius, A. floridanus, and A. industani and the generation times (T) for each of the three species were: 35.2, 29.9 and 37.8 days, respectively.

Animals↗
PubMed2004

Prevention of allergic disease in childhood: clinical and epidemiological aspects of primary and secondary allergy prevention.

The development and phenotypic expression of atopic diseases depends on a complex interaction between genetic factors, environmental exposure to allergens,and non-specific adjuvant factors, such as tobacco smoke, air pollution and infections. Preventive measures may include both exposure to allergens and adjuvant risk/protective factors and pharmacological treatment. These measures may address the general population, children at risk for development of atopic disease (high-risk infants), children with early symptoms of allergic disease or children with chronic disease. The objective for this review was to evaluate possible preventive measures as regards prevention of development of allergic disease in childhood--primary prevention--and also some aspects of the effect of specific allergy treatment as regards secondary prevention in children with allergic asthma and allergic rhinoconjunctivitis. In one prospective observational study of a birth cohort of unselected infants we evaluated possible predictive/risk factors. In two prospective intervention studies including 1 yr birth cohorts of high-risk(HR) infants we investigated the effect of feeding HR infants exclusively breast milk (BM) and/or hydrolyzed cow's milk-based formula the first 4-6 months as regards: (i) the allergy preventive effect of BM/extensively hydrolysed formula (eHF) compared with ordinary cow's milk-based formula, (ii) the effect of two different eHFs, a whey (Profylac) and a casein-based (Nutramigen) formula, as regards development of cow's milk protein allergy (CMA), and (iii) a comparison of the preventive effect of eHF (Profylac/Nutramigen) with a partially hydrolyzed cow's milk-based formula (pHF) (NanHA) as regards development of CMA. None of the mothers had a restricted diet during pregnancy or lactation period. In two prospective randomized intervention studies we evaluated the preventive effect of specific allergen avoidance and specific immunotherapy (SIT) in children with allergic asthma and allergic rhinoconjunctivitis, respectively. The combination of atopic heredity and elevated cord blood IgE resulted in the best predictive discrimination as regards development of allergic disease. The optimal high-risk group was defined by either double parental atopic predisposition or single atopic predisposition, the latter combined with a cord blood IgE > or = 0.3 kU/1. 66% of unselected infants were daily exposed to tobacco smoke, which was a significant risk factor for recurrent wheezing until the age of 1.5 yr. HR infants were breastfed for a longer period and less exposed to tobacco smoke than unselected infants. Exclusively BM/eHF for at least 4 months was associated with a significantly reduced cumulative prevalence of CMA [3.6% (5/141) vs. 20%(15/75) in the control group] up to 5 yr. The effect of the two different eHFs was similar. Exclusively breastfed infants were significantly less exposed to tobacco smoke and pets, had solid foods introduced later and belonged to higher social classes. pHF was significantly (p = 0.05) less effective than eHF as regards prevention of development of CMA. A diet period of 4 months seems to be as efficient as 6 months or more as regards development of CMA. A few ongoing prospective, randomized intervention studies have produced the first indication that avoidance of indoor allergens such as house dust mite (HDM) in HR infants may reduce the incidence of severe wheeze and sensitization during the first 1-4 yr of age. Long-term follow-up is awaited. In a prospective, double-blind placebo-controlled study in children with doctors diagnosed asthma and documented HDM allergy, we found that semipermeable polyurethane mattress and pillow encasings (Allergy Control) when compared with placebo encasings resulted in a significant perennial reduction of HDM exposure and a significant reduction in the needed dose of inhaled steroids by approximately 50% (mean dose: 408 microg--227 microg/day) after 1-yr follow-up. In another randomized prospective study we investigated the possible preventive effect of SIT in children with allergic rhinoconjunctivitis and grass/birch pollen allergy as regards development of asthma. Among those without asthma significantly fewer in the SIT group developed asthma when compared with the control group (19/79 = 24% vs.32/72 = 44%) after the first 3 yr; and methacholinebronchial provocation test results improved significant in the SIT group. The results of our studies support the evidence that the risk for development of early allergic manifestations e.g. CMA and atopic dermatitis can be reduced significantly by simple dietary measures for the first4 months of life. In all infants breastfeeding should beencouraged for at least 4-6 months, and exposure to tobacco smoke should be avoided during pregnancy and early childhood. In HR infants a documented hypoallergenic formula (at present eHF) is recommended if exclusive breastfeeding is not possible for the first 4 months. In homes of HR-infants, current evidence supports measures to reduce the levels of indoor allergens. e.g. HDM and pets. In symptomatic children allergen-specific treatment may influence both the symptoms and the prognosis. Allergen avoidance can reduce the need for pharmacological treatment, SIT may have the potential for preventing the development of asthma in children with allergic rhinoconjunctivitis. and it may be possible to interfere with the natural course of allergic diseases.

Adolescent↗
PubMed1993

Ultrastructural changes of Arabidopsis thaliana pollen during final maturation and rehydration.

Several ultrastructural changes occur during dehydration and subsequent rehydration of Arabidopsis thaliana pollen. The cytoplasmic channels, present in the outer part of the intine of the mature, dehydrating pollen grain, degenerate and develop into electron-dense inclusions. At the same time a large quantity of electron-dense material is deposited in the cavities of the exine. A large number of vesicles is produced in the vegetative cell, and they become predominantly located in the peripheral region near the intine. Starch of amyloplasts is consumed and the lipid bodies which originally surround the sperm cells become randomly distributed. In addition, the individual lipid bodies become enveloped by single rough endoplasmic reticulum cisterns.

Arabidopsis↗
PubMed2003

Characterization and localization of the transmitting tissue-specific PELPIII proteins of Nicotiana tabacum.

The class III pistil-specific PELP proteins (PELPIII) of Nicotiana tabacum includes at least two members of highly soluble glycoproteins containing glucan modules that are characteristic for arabinogalactan proteins (AGPs). PELPIII accumulates in the style transmitting tissue (TT) during pistil development and, at flower anthesis, is present in the intercellular matrix (IM) of non-pollinated pistils. After pollination, PELPIII appears to be directly and completely translocated from the IM into the pollen tube callose walls, no significant accumulation was observed in the primary wall in the tip. In the spent parts of the pollen tubes these proteins become detectable against the remnants of the tube cell membrane and in the callose plugs. Different protein extraction procedures of PELPIII from pollinated tobacco pistils showed that these proteins remain in the highly soluble protein fraction and are not modified by the growing pollen tubes. These data concur with a role in IM development and pollen tube growth. In addition, the data show that the PELPIII are able to reach the cell membrane, facilitated by an already present or induced high porosity of the tube wall and an additional, yet unknown, mechanism. The differences in behaviour between the three related classes of style IM glycoproteins of Nicotiana, namely, PELPII, TTS and the 120 kDa glycoprotein, are proposed to connect more to their differences in glycosylation than to major differences in amino acid sequence.

Blotting, Western↗
PubMed2003

Flexible mating: cross-pollination affects sex-expression in a marine clonal plant.

Many functionally hermaphroditic plants have evolved mechanisms to reduce interference between the sex functions and to optimize reproductive output. In addition to physical mechanisms such as the spatial (herkogamy) and temporal (dichogamy) separation of male and female functions, plasticity in sex expression by means of mate-recognition (flexible mating) could be important in plants with variable access to cross-pollen. This applies particularly to clonal plants because of their modular growth form. We experimentally tested for the effects of pollen source and vegetative neighbourhood on instantaneous sex ratio and seed production in the self-compatible clonal marine angiosperm Zostera marina L. To this end, we exposed the (monoecious) flowering shoots to self and cross-pollen and to neighbourhoods of their own and a mix of foreign vegetative shoots. Flowering shoots that had been exposed to cross-pollen showed (1) a significantly lower female/male ratio at peak flowering, evidence for mate-recognition, and (2) a significantly higher seed set by the end of the season. Both effects were independent of the genetic composition of their vegetative neighbourhood. The results suggest that Z. marina maintains a cryptic self-incompatibility system not previously described for angiosperms with sub-aqueous pollination. In Z. marina, and possibly other self-compatible clonal plant species, mate-recognition could be a means of increasing the out-crossing probability for flowering shoots with central positions within their clone.

Biological Evolution↗
PubMed1989

A simple method for staining nuclei of mature and germinated maize pollen.

A sugar acetocarmine staining technique has been developed for staining the sperm and vegetative nucleus of mature and germinated maize pollen grains. This procedure is simple, stable and highly repeatable. The physiological properties of the mature maize pollen grains are first adjusted by using an in vitro germinating culture solution. This solution is 15% sucrose and contains 360 ppm calcium chloride dihydrate, and 120 ppm boric acid. One part fresh pollen grains is uniformly mixed with nine parts of the solution and left at room temperature for at least 5 hr. One part of this solution is then mixed with two parts of regular acetocarmine stain and left overnight. The color of this mixture is pinkish red or raspberry. The sugar in the mixture helps to increase color contrast between the pollen cytoplasm (light pink) and the nuclei (reddish purple), decreases the frequency of burst pollen, increases pollen expansion, stabilizes pollen figures and automatically seals the coverglass.

Anthraquinones↗
PubMed2001

Quantification in mass units of group 1 grass allergens by a monoclonal antibody-based sandwich ELISA.

BACKGROUND: Grass pollen extracts currently used for allergy diagnosis and immunotherapy are a complex mixture of proteins of which only a few have allergenic activity. Lol p 1 is one of the most important allergens in grass pollen extracts. OBJECTIVES: To develop a two-site enzyme-linked immunosorbent assay for the quantification of Lol p 1 and other group 1 allergens from grass species, and to assess its suitability for quantifying this group of allergens. METHODS: Balb/c mice immunized with recombinant Lol p 1 were used for the production of monoclonal antibodies. Screening of hybridomas was performed by direct ELISA, and selected monoclonal antibodies were immobilized on ELISA plates and incubated with samples containing group 1 allergens. Bound allergens were detected by a combination of biotinylated Lol p 1-specific monoclonal antibody and peroxidase-streptavidin conjugate. RESULTS: The assay is based on three Lol p 1-specific monoclonal antibodies with different epitope specificities. The optimized ELISA measured Lol p 1 concentrations ranging from 125 to 1000 ng/mL and could quantify group 1 allergen from grass species belonging to the Pooidea subfamily. The assay does not depend on anti-sera production or availability of human sera and thus reactives can be produced in unlimited amounts. CONCLUSION: This sensitive and specific Lol p 1 assay will be helpful both for quantifying the group 1 allergen content of Pooideae pollen extracts intended for clinical use and for studying cross-reactivities among pollen extracts.

Allergens↗
PubMed1993

Pollen.

This review deals first with basic knowledge about pollen, especially its biology, morphology and physiology, and then discusses the connection of pollen with medical problems such as hay fever (pollinosis). The next sections cover the historical development of methods for trapping and counting airborne pollen grains to produce reliable quantitative data, and the development of a European network of pollen-reporting stations.

Environmental Monitoring↗
PubMed2006

Search for low-allergenic apple cultivars for birch-pollen-allergic patients: is there a correlation between in vitro assays and patient response?

BACKGROUND: Due to the cross-reactivity between Bet v 1 and proteins present in vegetable foods, birch pollen allergic patients frequently develop allergy to fruits and vegetables, mostly apples. Since many apple cultivars exist some of them might contain sufficiently low amounts of Mal d 1 to be tolerated by most allergic patients. OBJECTIVE: To assess whether apple cultivars containing low amounts of Mal d 1 are better tolerated by apple-allergic patients. METHODS: Mal d 1 content was determined in many apple cultivars by ELISA. Selected cultivars containing high (Golden Delicious) or low (Orim, G 198 and Vienna) amounts of Mal d 1 were compared in apple allergic patients both by SPT and oral challenges. RESULTS: The 3 different apple cultivars induced wheals of similar size in most patients. Upon oral challenges no patient reported the total absence of oral symptoms following the ingestion of either high or low allergenic apples. Golden Delicious and G-198 elicited OAS of similar severity 3/7 cases. The 2 cultivars induced significantly more severe symptoms in 2 cases each. CONCLUSION: Allergy to Mal d 1 is characterized by significant inter-patient variability. Moreover, marked inter-apple and intra-apple variability exists. As a consequence, the amount of Mal d 1 in apples classified as containing low concentrations of allergen may be sufficient to induce both clinical symptoms and skin reactivity in birch pollen-allergic patients. The search for low allergenic apples therefore should be continued and extended to other germplasm accessions, be it cultivars, breeding lines or wild species.

Administration, Oral↗
PubMed1997

Stochastic Dispersal Processes in Plant Populations

A dispersal model for airborne pollen based on assumptions about wind directionality, gravity, and a wind threshold at which pollen is taken by the wind is developed, using a three dimensional diffusion approximation. The bivariate probability distribution of pollen receipt by flowers at the same height as the pollen source is derived. Gravity, vertical random movements, and vegetation density turn out to have similar effects on this distribution. Maximum likelihood methods for estimating the combined parameters from data with multiple point or continuous pollen sources, and one or more plant varieties, are developed. Using an example data set from the literature, it is shown that our model gives a better fit than more traditional descriptive dispersal models of the form e-ar b. We also show that estimates of important properties of the dispersal distribution, such as the variances, become considerably smaller using our model than for the more traditional models. Finally, we discuss potential extensions and evolutionary implications of these types of models. Copyright 1997 Academic Press

Journal Article↗
PubMed1997

Promoter sequences of two homologous pectin esterase genes from Chinese cabbage (Brassica campestris L. ssp. pekinensis) and pollen-specific expression of the GUS gene driven by a promoter in tobacco plants.

The promoter regions of two genomic clones, GBAN215-6 and GBAN215-12 from Chinese cabbage (Brassica campestris L. ssp. pekinensis), were sequenced. The nucleotide sequences of their promoter regions were compared with that of the Bp19 pollen-specific gene of Brassca napus. High nucleotide sequence homologies were observed among these three genes in the region between 210 bp upstream and the putative transcription start site. A sequence motif TGTGGTG, which is similar to that of the PB core motif (TGTGGTT) of two tomato pollen-specific genes, LAT52 and LAT56, was present in these two cloned genes. To determine regulatory sequences responsible for the anther-specific expression of the gene BAN215-6, two recombinant plasmids, pBPE3 (-274- + 109) and pBPE4 (-816- + 109) containing different lengths of the promoter fused with the GUS gene, were constructed and introduced into tobacco plants by Agrobacterium-mediated transformation. The result showed that the 383 bp (-274- + 109) of the BAN215-6 promoter region was sufficient for the anther-specific expression of the GUS gene. The GUS expression in a tobacco plants transformed with these constructs was first detected in uninucleate microspores and persisted at in vitro germinated pollen tubes. The expression level was increased during anther development, reaching the highest level in mature pollens.

Brassica↗
PubMed1998

Adaptation of hypopharyngeal gland development to the brood status of honeybee (Apis mellifera L.) colonies.

We studied pollen consumption, head weight, hypopharyngeal gland (HPG) acini diameter, and protein synthesis and transfer in honeybee workers reared in colonies with normal and with decreasing amounts of brood. We found that head fresh weight is correlated with size of the glands and that pollen consumption is positively correlated with gland development. An effect of brood on size of the glands could be confirmed, but was not as profound as in previous studies. Similarly, no difference in the amount of protein synthesized or transferred in workers living under the two brood conditions was found. We suspect this is due to the fact that HPGs also supply food to young bees and in our study young bees were always present while in previous studies, colonies often lacked both brood and young bees.

Journal Article↗
PubMed1999

[Cyto-embryologic investigation of super dwarf wheat grown on board of the Mir orbital complex].

The cytoembryologic analysis of wet and dry samples of super dwarf wheat cultivated in greenhouse SVET aboard the MIR station over the whole cycle of vegetation was made with the use of light microscopy. Characteristic features of wheat development in space flight are plentiful early tillering, and formation and rapid growth of side shoots. Elementary spikelets in the composite head were more numerous but the top spikelets were rudimentary and, therefore, the ripe head contained less of these spikelets as compared with the ground controls (9-13 and 14, respectively). The number of florets in a spike was also higher reaching 14-16 vs. 7-8 in the control. Typically, no more than 4 to 5 florets vs. 3 in the control were fully differentiated while the others died off earlier in development. The fact that there were no caryopses found in the flight crop is explained by absolute male sterility appearing at different stages of staminal development: before archesporium formation, on the stage of differentiated archesporium, during meiosis, on the stage of microspores or uninucleate "pollen". The female generative system developed mainly without abnormalities. An assumption was made that elevated ethylene concentrations in the MIR atmosphere at the time of the wheat experiment were the cause for abnormal development of the male generative system which led to barrenness of the super dwarf wheat crop.

Animals↗