Fertile Pollen Grains Research Articles

Fertility and Viability of Pollen Grains of Taraxacum officinale Wigg. s.l. (Asteraceae, Magnoliopsida) in a Gradient of an Anthropogenically Transformed Environment

The fertility and viability of pollen grains of two morphological forms of Taraxacum officinale Wigg. s.l. were estimated. These forms compose common coenopopulations growing in various coenotic and edaphic conditions. The forms studied possess developed gynoecia—a large number of fertile pollen grains capable of germinating under certain temperature conditions. This fact points to the amphimictic properties of the plants. Comparison of the data on the fraction of fertile pollen grains and seed productivity allows assuming that some seeds develop without fertilization. This can be considered as evidence of the apomictic properties of plants. Therefore, the presence of facultative apomixis in the species considered was confirmed indirectly in our work. The fertility of pollen grains was shown to be a characteristic of the male gametophyte that was more environmentally dependent than its viability. Under favorable conditions, the share of fertile pollen grains in f. dahlstedtii and f. pectinatiforme differ insignificantly. Under stress, the differences between the dandelion forms by this index increase. This can be considered as a mechanism of adaptation to adverse environmental factors. The revealed differentiation of the morphological forms of dandelions by the index of pollen grain fertility suggests that edaphic and coenotic stresses increase the differences between them in the degree of apomictic and amphimictic properties. The morphological forms of dandelions, by realizing two reproductive strategies under stress, ensure both the abundance and the genetic heterogeneity of the coenopopulations. The morphological forms studied do not differ in the proportion of viable pollen grains. This index increases in the gradient of coenotic competition only to a certain extent, which can be considered as a manifestation of the properties of the facultative apomict.

Fertility and Viability of Pollen Grains of <i>Taraxacum officinale</i> Wigg. s.l. (Asteraceae, Magnoliopsida) in the Gradient of an Anthropogenically Transformed Environment

The fertility and viability of pollen grains of two morphological forms of Taraxacum officinale Wigg. s.l were estimated. These forms compose common coenopopulations growing in various coenotic and edaphic conditions. The studied forms have a developed gynoecia – a large number of fertile pollen grains capable of germination under certain temperature conditions. This points to the amphimictic properties of the plants. Comparison of data on the fraction of fertile pollen grains and seed productivity allows one to assume that some seeds develop without going through fertilization. This can be treated as evidence of the apomictic properties of the plants. Therefore, the presence of optional apomixis in the species in question was indirectly confirmed in the course of our work. The fertility of pollen grains was shown to be a more ecology-dependent property of the male gametophyte than its viability. In the favorable conditions the part of fertile pollen grains in f. dahlstedtii and f. pectinatiforme differs insignificantly. Under stress conditions, the differences between the forms of the dandelion by this indicator amplify. This can be considered as a mechanism of adaptation to adverse environmental factors. The revealed differentiation of the morphological forms of the dandelion by the indicator of the fertility of pollen grains enables one to assume that edaphic and coenotic stresses lead to an increase in the differences between them by the degree of apomictic and amphimictic properties. The morphological forms of the dandelion, realizing two reproductive strategies under stress conditions, support both the quantity and genetic heterogeneity of the coenopopulations. The morphological forms studied do not differ in the proportion of viable pollen grains. This indicator rises to a certain extent only in the gradient of coenotic competition. This can be considered as a manifestation of the properties of optional apomict.

Comparative transcriptome analysis reveals the mechanism of exogenous substances inhibiting fertility alteration induced by low temperature in TGMS rice line

During two-line hybrid rice seed production, thermo-sensitive genic male sterile (TGMS) rice lines are susceptible to low temperature, leading to fertility alteration (from sterile to fertile) and production of false hybrids (self-pollination). To explore appropriate solutions to reduce the chance of seed production failure, two exogenous substances, d-Arg and ethephon, were applied to restrain the fertility alteration induced by low temperature (22.0 °C), respectively. The fertile pollen grains and bagged seed setting rate of TGMS rice line Jing 4155S (with the critical fertility/sterility alteration temperature of 23.5 °C) under low temperature could be reduced to 0% by spraying exogenous substances. Transcriptome analysis of young panicles of TGMS rice line Jing 4155S demonstrated that the expressions of multiple transcription factors (MYB, FAR1, and ERF, etc.) changed, and hence affecting various downstream related genes and metabolic processes, including hormonal signal transduction, plant pathogen interactions, circadian rhythm pathway, carbohydrate metabolism, cell wall synthesis, and lipid metabolism, etc. The enhanced ethylene biosynthesis and the prevented redox equilibrium from unbalance to balance in young panicles were one of the major reasons that fertility alteration was inhibited by exogenous substances. Our results made a contribution to the solution for inhibiting fertility alteration induced by low temperature in two-line TGMS rice lines during hybrid seed production.

Effects of air temperature, humidity and air pollution on fertility of birch pollen in urban environments

We studied effects of environmental factors on pollen fertility of Betula pendula Roth.) in 15 sites of the city of Barnaul (Russia, Altai Territory), differing in traffic intensity. We found that low temperature was more stressful for the development of birch pollen compared to high one. When the temperature drops below +8°C, the amount of sterile pollen in all locations significantly increased regardless of the anthropogenic load, on average exceeding 8%. With an increase in temperature of more than +10 °C, the proportion of sterile pollen also increased, but the jump was not as sharp as in cold weather. The optimum temperature for the formation of fertile pollen grains was in the range of 8–10 °С. The optimal humidity for the development of fertile pollen of B. pendula was 40–45%. The increase in air dryness led to a significant decrease in the quality of pollen grains, the proportion of sterile ones exceeded 8%. According to the transmission coefficient (Keff = 0.1514), the dominant factor in the development of sterile pollen grains of birch was the level of air pollution (concentration of carbon monoxide). Air temperature (Keff = 0.1427) and humidity (Keff = 0.1427) affected equally the quality of pollen. The proposed model makes it possible to predict the level of sterile birch pollen in the conditions of Barnaul depending on the weather conditions of vegetation and on the level of pollutants in the atmosphere.

A report of aneuploidy and cytomixis in rare and endemic species of central India: Cyathocline lutea Law ex Wight

Cytological analysis of rare and endemic species Cyathocline lutea Law ex Wight (Asteraceae) of Maharashtra, India have been reported in the present study. This is the first aneuploid report for this species revealing chromosome count of n = 9. Meiotic irregularity like cytomixis has been observed for the first time in this species resulting in the formation of hypoploid and hyperploid PMCs which in turn resulted in two types of pollens. The frequency of cytomixis in PMCs was calculated as 10.55%. Pollen grain study revealed some small sterile unstained pollen (12.35%) and large fertile stained pollen (87.64%). The size of fertile pollen grains was 21.02–33.83 × 20.92–24.39 µm while sterile pollens were 18.04–24.53 × 16.85–20.48 µm.

Functional androdioecy in the ornamental shrub Osmanthus delavayi (Oleaceae).

Androdioecy is one of the rarest sexual systems among plants, characterized by males co-occurring with hermaphrodites. Osmanthus delavayi (Oleaceae), an ornamental shrub from southern China, is known to have both male and hermaphrodite individuals, but little is known regarding the breeding system of this species and whether it is functionally androdioecious, and how this potentially evolved. In this study, we explore the characteristics of the breeding system of O. delavayi through the study of phenology, sex ratio, floral organ morphology, pollen number, stigma receptivity, artificial pollination, pollinators, and gene flow within and between populations, while also discussing the evolution and maintenance of androdioecy within the genus. The proportion of males was less than 0.5 and the out-crossing index (OCI) was 5. Morphological androdioecy was observed, with hermaphrodite flowers having fertile pistils, while male flowers had degenerated pistils. Males and hermaphrodites both had large amounts of small and fertile pollen grains, although the pollen number of males was ca. 1.21 × more than that of hermaphrodites, and pollen was generally smaller. Self-pollination was found to produce a much lower fruit set than outcrossing under natural conditions. Gene flow between males and hermaphrodites within a population was greater (1.007) than that between populations (0.753). All these results indicate that O. delavayi is functionally androdioecious, which may be an intermediate state in the evolutionary transition from hermaphroditism to dioecy.

The influence of urban environment on pollen grains of the silver birch (<i>Betula pendula</i> Roth) in conditions of Yakutsk

This paper studies variability of pollen grains of the silver birch in relation to the quality of urban environment. The material was collected in 12 sites. A total of 1,190 leaves and 24,000 pollen grains were examined and measured. The pollen fertility varied within 6992%. Statistically significant decrease in fertility was observed in conditions of high-intensity traffic load, in the central area of the city, and where the road surface was in poor condition. Under the same conditions a statistically significant increase in percentage of relatively fertile pollen grains is observed. We found significant correlation between the level of fluctuating asymmetry (FA) and the share of fertile and half-fertile pollen grains. For fertility Spearmans rho was 0,71; and for half-fertility, r = 0,66, p 0,05. A similarly significant correlation (r = 0,7, p 0,05) was found between the diameter of pollen grains and traffic load, which indicates a consistent organism response to environment deterioration. From the above, it follows that for assessment of environmental condition such characteristics of pollen grains as fertility, half-fertility, and pollen grain size can be used.

Quantitative and qualitative analysis of sunflower pollen (<i>Helianthus</i> L.) and it’s use in breeding work

Background. In breeding work, it is necessary to take into account such an important feature as male sterility of the hybrids obtained. If a plant has visually visible anthers and pollen, the quality of the pollen grains themselves may be low. It is necessary to carry out not only a visual analysis, but also a cytological study of pollen in order to properly assess the reproductive potential of plants.Materials and methods. Wild species, some cultivars, lines and hybrids of sunflower from the collection of the N. I. Vavilov All-Russian Institute of Plant Genetic Resources were taken as objects of research. The plants were grown on the fields of Kuban Experiment Station. Pollen was collected from preinsulated inflorescences, fixed in FAA solution and stained with acetocarmine. The ratio of fertile pollen grains to the total number of pollen grains (in %) was calculated, the diameter of the pollen grains was measured, and variability curves were drawn.Results. Mature pollen grains in sunflower are rounded, tricolpate-poral, threecelled; the average pollen diameter in cultivated sunflower is 28–32 μm; in wild species, the range is from 20– 22 μm to 32–34 μm. All accessions were divided into three groups. Fertile: high level of fertility (75–99%) and low morphological heterogeneity of pollen; the variation curve for the average diameter was characterized by one distinct peak. Most of the studied accessions were included here: cultivars, most of the lines and some of the wild species. Semi-fertile: the number of well-stained pollen grains is below 75%; there are differences in the degree of staining and size of the pollen; the variation curve had additional peaks. This group included some of the lines, hybrids and wild species. The greatest morphological heterogeneity was observed in the group of perennial interspecific hybrids. Sterile: pollen grains were absent or were observed very sporadically.Conclusion. To assess the fertility of plants, it is important not only to determine the degree of staining in pollen grains, but also to rank them by diameter and construct variation curves to reveal morphological heterogeneity of pollen.

Еколого-біологічна оцінка запилення та фертильність сортів фундука в умовах Правобережного Лісостепу України

Наведено результати досліджень фертильності та життєздатності пилку сортів фундука в умовах Правобережного Лісостепу України. У досліді використано свіжозібраний пилок і через кожні дві години зафіксовано початок та динаміку його проростання. Частка життєздатного пилку визначено через 24 години за кількістю пророслих пилкових зерен у 10 полях зору мікроскопа. Пророслими вважали пилкові зерна, трубки яких мали довжину не менше, ніж діаметр пилкових зерен. Використано пилковий матеріал сортів фундука Лозівський кулеподібний, Дар Павленка, Софіївський 15, Галле, Футкурамі, Черкеський-2. Проведені дослідження свідчать про те, що розміри пилкового зерна більш вирівняні та трапляються від 25,5 до 34 мікрон, за формою фертильні пилкові зерна округлі, рідко зустрічаються трикутні. Стерильні пилкові зерна відрізняються від фертильних менш інтенсивним забарвленням та мають не чітку округлу форму. Після оцінювання якості пилку видно, що частка фертильних пилкових зерен високий і становить від 95,1 % у сорту Лозівський кулеподібний до 45,4 % у сорту Футкурамі, стерильних від 52,4 до 3,5 %, а деформованих у межах 4 %. Внаслідок проведених досліджень встановлено, що для пилку фундука властива досить висока життєздатність і фертильність. Так для максимального проростання пилку оптимальним є середовище з 15 % розчину сахарози, на якому найвища частка пророслого пилку зафіксовано в сорту Лозівський кулеподібний – 69,8 %, найнижчий показник у сорту Черкеський-2-33,1 %. Збільшення концентрації сахарози призводило до зменшення кількості пророслих зерен, пилкові трубки ставали коротшими і викривленими. Найвища частка фертильності пилку спостережено в сорту Лозівський кулеподібний – 95,1 %, найнижчий у сорту Футкурамі – 45,4 %.

Influence of Pollen Germination Capacity on a Successful Artificial Hybridization in Cyclamen sp

The artificial hybridization is one of the most important methods to create variability in breeding programs. The success of artificial hybridization very often depends on the fertility of pollen grains which require a minimum 30% germination level. The aim of the present study was to identify the correlation between the level of pollen grain fertility and success of hybridization in several cyclamen cultivars. There were taken under study seven cultivars of Cyclamen sp. very different from phenotypic point of view (maxi, midi, mini). In the first step it was determinated the germination capacity of pollen grains trough viability and germinability percentage and the correlation between these two determinations. The results show a higher ratio of viability then germinability in all cultivars. The best results of artificial hybridization were registered in hybrid combinations in which there were used cultivars with the highest percentage of pollen fertility. Out of seven cyclamen cultivars tested in 18 hybrid combinations, three cultivars showed the highest level of fertility when used as male genitor (Curly White; Curly Magenta Picotee and Allure Salmon Flamed)for a further study on phenol biodegradation especially areas with phenol contamination containing some heavy metals.

Cytogenetical Assessment of Apiaceae Lindl. From District Sirmaur, Himachal Pradesh, India

During the present study, population-based meiotic studies were carried out on 10 species of Family Apiaceae from selected localities of district Sirmaur of Himachal Pradesh in the Western Himalayas (India). New chromosome counts in Heracleum canescens (2n=22) and Pleurospermum brunonis (2n=22) have been reported for the first time on world-wide basis. Furthermore, meiotic course was noted to be normal in Bupleurum lanceolatum, B. longicaule, Heracleum brunonis, Sanicula elata, Selinum tenuifolium, S. vaginatum and Vicatia coniifolia, it varied from normal to abnormal in the populations of Bupleurum hamiltonii and Heracleum canescens whereas it was invariably found to be abnormal in all the populations of Pleurospermum brunonis. These anomalous taxa were marked with meiotic abnormalities in the form of cytomixis, chromosomal stickiness, unoriented bivalents, formation of laggards and bridges resulting in abnormal microsporogenesis, and production of heterogeneous-sized fertile pollen grains along with reduced pollen fertility.

Flower development and pollen vitality of Moringa oleifera Lam. grown in a humid temperate climatic condition

Moringa oleifera is a tropical tree cultivated in many countries. This species has acquired a great importance in human nutrition and it was recently indicated as a “novel food” by the European Commission. Recently, moringa plants have been introduced in humid temperate climatic areas, among which Moreno (Buenos Aires Province - Argentina). In such area, the cultivation is possible for the production of leaves, but plants need protection during winter time in order to overcome damages due to low temperatures and hence to produce capsules and seeds. The main objective of this research was to study flower morphology and anatomy of M. oleifera, as well as microsporogenesis and viability of pollen grains of plants cultivated in Moreno in comparison with those produced in a humid sub-tropical climatic area of Argentina (San Miguel de Tucuman). Flowers grown in the temperate environment resulted similar for morphological parameters to those observed in the sub-tropical environment. Nevertheless, pollen grain fertility depended directly on air temperature and it was negatively affected by the lower temperatures registered in the temperate site. According to the observed results, pollen viability increases with mean monthly temperatures above 16°C.

Introduction species of the genus Eupatorium L. in the southern taiga subzone of Western Siberia

The article contains results of six years of observations of introduced populations of Eupatorium cannabinum L., E. maculatum L., E perfoliatum L. and E purpureum L. Seasonal rhythms of development are revealed, some antecological features are investigated, elements of seed productivity are counted and laboratory germination of seeds is estimated. It is established that the studied species are in the full cycle of seasonal development in the southern taiga subzone of Western Siberia: all species are stable vegetate, bloom and bear fruit. Plants are referred to a group of long-term vegetation and summer flowering period cultures. It was found that the flowers of the Eupatorium are characterized by dichogamy in the form of protandry. Species are inherent by high coefficients of seed productivity and fertility of pollen grains. Size indicators of seeds and pollen grains are stable, have a low level of coefficient of variation. Stratification increases the germination of seeds in two times. The studied species can be recommended for use in mixborders, various compositions of landscape style, in the design of garden reservoirs.

Genome-Wide Gene Expression Disturbance by Single A1/C1 Chromosome Substitution in Brassica rapa Restituted From Natural B. napus.

Alien chromosome substitution (CS) lines are treated as vital germplasms for breeding and genetic mapping. Previously, a whole set of nine Brassica rapa-oleracea monosonic alien addition lines (MAALs, C1-C9) was established in the background of natural B. napus genotype “Oro,” after the restituted B. rapa (RBR) for Oro was realized. Herein, a monosomic substitution line with one alien C1 chromosome (Cs1) in the RBR complement was selected in the progenies of MAAL C1 and RBR, by the PCR amplification of specific gene markers and fluorescence in situ hybridization. Cs1 exhibited the whole plant morphology similar to RBR except for the defective stamens without fertile pollen grains, but it produced some seeds and progeny plants carrying the C1 chromosome at high rate besides those without the alien chromosome after pollinated by RBR. The viability of the substitution and its progeny for the RBR diploid further elucidated the functional compensation between the chromosome pairs with high homoeology. To reveal the impact of such aneuploidy on genome-wide gene expression, the transcriptomes of MAAL C1, Cs1 and euploid RBR were analyzed. Compared to RBR, Cs1 had sharply reduced gene expression level across chromosome A1, demonstrating the loss of one copy of A1 chromosome. Both additional chromosome C1 in MAAL and substitutional chromosome C1 in Cs1 caused not only cis-effect but also prevalent trans-effect differentially expressed genes. A dominant gene dosage effects prevailed among low expressed genes across chromosome A1 in Cs1, and moreover, dosage effects for some genes potentially contributed to the phenotype deviations. Our results provided novel insights into the transcriptomic perturbation and gene dosage effects on phenotype in CS related to one naturally evolved allopolyploid.

Effect of flower density on pollen viability and fruit set of Calceolaria tripartita Ruiz &Pav. (Scrophulariaceae) in Darjeeling Himalaya

<p>There are many populations in a 16 km east-west distribution and populations are usually small with fewer than 100 plants/clumps. The pollen biology in terms of pollen production, pollen-ovule ratio estimation, pollen viability and pollen fertility was studied to determine the impact of plant and flower density on pollen viability and fruit set of <em>Calceolaria tripartita</em> Ruiz &Pav. (Scrophulariaceae) in Darjeeling Himalaya. It is revealed that higher the density of the plants and flowers, the productivity of pollens and ovules and the viability and fertility of pollen grains become higher showing a positive correlation between plant-flower density vs. pollen biology. Fruit set is higher in high dense flowering site than low ones which might be due to higher pollen fertility rate, low sterility and greater number of pollen load upon stigma. Thus, it reflects that plant and flower density has a crucial role upon the reproductive fitness of this taxon.</p>

First Report of Intraspecific Polyploidy (2<i>x</i>, 4<i>x</i>) in <i>Physochlaina praealta</i> (Decne.) Miers. (Family: Solanaceae)

Physochlaina praealta (family: Solanaceae), a widely distributed species of Indian cold deserts, is studied for male meiotic studies. We here report for the first time the existence of intraspecific polyploidy (2x, 4x) in the species. Both the 2x and 4x individuals show perfectly normal meiotic behavior and nearly 100% fertile pollen grains. The 4x plants show allopolyploid like meiotic behavior characterized by normal chromosome pairing and regular segregation of chromosomes. The 2x and 4x plants grow under similar type of habitats but the 4x individuals were noticed to be more pubescent. The 4x plants can also be differentiated from the 2x on the basis of micro-characters like trichome (size, density), stomata (size and frequency) and pollen grain size which increases with ploidy.

Фертильність і життєздатність пилкових зерен рослин сортів Iris hybrida hort., інтродукованих за умов Лісостепу України

Фертильність і життєздатність пилкових зерен рослин сортів Iris hybrida hort., інтродукованих за умов Лісостепу України

Evidence for Division of Labor and Division of Function Related to the Pollen Release in Papilionoideae (Leguminosae) with a Heteromorphic Androecium

Premise of research. Heterostemony occurs in all three traditional subfamilies of Leguminosae, but it is most commonly found in the Papilionoideae, which are characterized by papilionaceous corollas and complex pollen-releasing mechanisms. Our objective was to evaluate evolutionary and reproductive advantages of heterostemony in papilionoid legumes.Methodology. We investigated the functionality of pollen grains and floral ontogeny of two heterostemonous papilionoid species, Lupinus “The Governor” and Cytisus scoparius, using SEM, LM, and TEM techniques.Pivotal results. Lupinus showed differences in pollen viability between the two stamen morphs. The antesepalous stamens (producing fertile pollen grains) are initiated in reversed unidirectional order and develop before the antepetalous stamens (producing sterile pollen grains). During the development, the keel petals fuse at their ventral and dorsal regions, forming a tube, which surrounds the reproductive column, leaving an apical opening through which th...

Cytological Studies of Some Vigna (L.) Walp. Species

Cytological studies were carried out on twenty-five accessions of six species of Vigna in order to assess their genetic relationships. The accessions composed of 6 accessions of V. unguiculata, ten accessions of V. vexillata, four accessions of V. luteola, one accession of V. ambacensis, two accessions of V. oblongifolia, and two accessions of V. racemosa. Somatic chromosome counts of 2n=22 were made for all the Vigna accessions studied and meiosis was observed to be regular in all the accessions with formation of eleven bivalents. The pollen studies revealed that all the accessions produced highly fertile pollen grains, which is the direct effect of regular meiosis observed in all the accessions. The mitotic metaphase chromosomes are very small and are largely metacentrics or submetacentrics. The study indicated that the karyotype number would not itself contribute to genetic incompatibility in interspecific crosses.

Morphological traits in an androdioecious species, Chionanthus retusus (Oleaceae)

Androdioecy is a reproductive system in which males coexist with hermaphrodites, which have both male and female functions. We present here the morphological differences in the sexual morph of flowers in Chionanthus retusus, an androdioecious species. Hermaphroditic floral organs, such as the corolla, calyx, and anther, are relatively larger than male ones (P<0.001), and they also produce well-structured, fertile pollen grains, demonstrating male function. However, pollen quality (productive and viability) of males is significantly higher than that of hermaphrodites (P<0.001). Both hermaphrodites and males have osmophores in the outer corolla and calyx, papillose inner corolla epidermal cells, and pollenkitt. These differences and similarities in traits and the completely sterile gynoecium of male flowers confirm that C. retusus is an androdioecious species. Moreover, mapping the breeding system onto the recently studied phylogenetic tree indicates that a clade belonging to C. retusus might be represent a shared androdioecious system.