Tristyly in Pontederia cordata (Pontederiaceae)

1982 ◽  
Vol 60 (6) ◽  
pp. 897-905 ◽  
Author(s):  
Steven D. Price ◽  
Spencer C. H. Barrett
Keyword(s):  
Breeding System ◽  
Natural Populations ◽  
Pollen Grains ◽  
Pollen Production ◽  
Foraging Activity ◽  
Reproductive Parameters ◽  
Style Length ◽  
Flower Production ◽  
System A ◽  
Pontederia Cordata

Pontederia cordata L. (Pontederiaceae) is a perennial, entomophilous, emergent aquatic and possesses a tristylous breeding system. A survey of 74 North American populations indicates that populations usually contain the three floral morphs. A strong pollen trimorphism is associated with differences in stamen and style length among the morphs. Pollen size is proportional to stamen height, while pollen production is inversely proportional. There are two size classes of anthers in P. cordata. Long-level anthers of mid- and short-styled plants and mid-level anthers of the short-styled morph are significantly larger than short-level anthers of long- and mid-styled plants and the mid-level anthers of the long-styled morph. The larger mid-level anthers of the short-styled morph produce nearly twice as many pollen grains as the equivalent level in the long-styled morph. It is suggested that this difference may be associated with varying patterns of stamen insertion and development in the floral morphs.Comparisons of various reproductive parameters among the floral morphs in natural populations suggest that there are no significant differences in flowering patterns, inflorescence and flower production, seed production, and germination levels. In addition, bumble bees show no apparent preferences among the floral morphs during foraging activity. Tristyly appears to be a relatively stable breeding system in P. cordata in comparison with tristylous species of the related Eichhornia.

Dioécie cryptique chez Geniostoma borbonica, espèce pionnière endémique de La Réunion

2003 ◽  
Vol 81 (9) ◽  
pp. 897-904 ◽  
Author(s):  
Laurence Humeau ◽  
Dominique Strasberg ◽  
Thierry Pailler
Keyword(s):  
Breeding System ◽  
Natural Populations ◽  
Pollen Grains ◽  
Floral Biology ◽  
Breeding Systems ◽  
Plant Succession ◽  
General Context ◽  
Cryptic Dioecy ◽  
Unisexual Flowers ◽  
Evolution Of Dioecy

In the general context of conservation of insular habitats, the floral biology, natural fecundity, and breeding system of Geniostoma borbonica (Lam.) Spreng. was studied in natural populations. The species, which was initially assumed to be gynodioecious, presents two kinds of individuals, both with morphological hermaphroditic but functionally unisexual flowers. Some individuals produce pollen grains, but neither ovules nor fruit, whereas other fructiferous individuals have anthers without pollen grains. Geniostoma borbonica is the first species in this genus to be reported as dioecious; its floral morphology illustrates an example of cryptic dioecy. This species combines an apomictic breeding system, assuring a fast installation without reproductive constraints, and a reproductive breeding system assuring maintenance of genetic variability in the population. These two breeding systems allow adaptation to evolution of the habitat during plant succession. This point is discussed in the colonization context of pioneer habitats, where herma- phro ditic species are recognized to be advantageous, as well as in the context of the evolution of dioecy in this genus.Key words: cryptic dioecy, pioneer habitat, oceanic island, Geniostoma.

SELFING ABILITY AND MALE STERILITY IN SENECIO VERNALIS WALDST. ET KIT. (ASTERACEAE) FROM ISRAEL

1994 ◽  
Vol 42 (2) ◽  
pp. 89-103 ◽  
Author(s):  
H.P. Comes
Keyword(s):  
Male Sterility ◽  
Breeding System ◽  
Male Fertility ◽  
Dominant Gene ◽  
Pollen Grains ◽  
Preliminary Evidence ◽  
Pollen Production ◽  
Male Sterile ◽  
Ovule Number ◽  
Selfing Ability

Two major findings relating to the breeding system of Senecio vernalis from Israel are reported. First, isolation experiments failed to confirm the existence of a widespread, truly self-compatible and predominantly self-pollinating breeding system in Israeli populations of S. vernalis. However, a single S. vernalis plant derived from a natural stand at Jerusalem was found to be self- compatible and strongly self-pollinating. In its progeny, there were signs of inbreeding depression commonly associated with selfed offspring of outbreeding species. Selfing ability ratios in this progeny indicate a single dominant gene for selfing ability in S. vernalis. The implications of these observations for the origin of S. vulgaris are briefly discussed. Second, the occurrence of gynodioecy in S. vernalis populations from Israel is reported. Although male sterile plants are recognizable by the complete absence of pollen on their exposed stigmas, there probably exists a large amount of variation within and between plants for pollen production. Infertile pollen grains of male steriles differ in size, shape, and sculpturing from those of hermaphrodites. At the Mt. of Olives, in Jerusalem, the frequency of male steriles was found to be 9.1%. There is some preliminary evidence for differences in floret (= ovule) number between the two gender types. Although the inheritance of male sterility appears to be predominantly cytoplasmically controlled, additional mechanisms restoring male fertility have to be postulated to account for the data observed in one of the crosses. The male sterility system in S. vernalis should therefore be referred to as “nuclear-cytoplasmic.”

Mitigating environmental impacts of milk production via integrated maize silage planting and dairy cow breeding system: A case study in China

2021 ◽  
pp. 127343
Author(s):  
Xianlei Huang ◽  
Boyang Shi ◽  
Shu Wang ◽  
Changbin Yin ◽  
Linna Fang
Keyword(s):  
Environmental Impacts ◽  
Milk Production ◽  
Dairy Cow ◽  
Breeding System ◽  
Maize Silage ◽  
System A

POLLEN PRODUCTION AND DISSEMINATING PROPERTIES OF TRITICALE RELATIVE TO WHEAT

1972 ◽  
Vol 52 (4) ◽  
pp. 569-574 ◽  
Author(s):  
K. C. YEUNG ◽  
E. N. LARTER
Keyword(s):  
Seed Set ◽  
Marker Gene ◽  
Pollen Grains ◽  
Triticum Aestivum L ◽  
Hybrid Seed Production ◽  
Pollen Production ◽  
Hexaploid Triticale ◽  
Anther Length ◽  
Anther Extrusion ◽  
Wide Range

A study of the pollen production properties of three hexaploid triticale strains (Triticale hexaploide Lart.) showed that their anther length was significantly greater than that of wheat anthers (Triticum aestivum L. em Thell.) and the estimated number of pollen grains per anther ranged from 15,000 to 21,000. In comparison, a total of 8000 grains per anther was estimated for wheat, cult Manitou. Eighty-nine percent anther extrusion occurred in triticale cult Rosner, while Manitou averaged 70% anther extrusion. The period of anthesis of triticale varied according to strain but generally was of longer duration than in Manitou and thereby promoted outcrossing. Using a triticale strain carrying a dominant marker gene, 50% seed-set was obtained at a distance of 12 m leeward of the pollen source; however, a small percentage was still obtained at a distance of 30 m. It would appear from the limited number of triticales used in this study that a wide range of variability exists within this species in its pollen production and disseminating properties. With appropriate selection pressures, strains with an outbreeding habit could be developed for the purpose of hybrid seed production.

scholarly journals ATBS1-INTERACTING FACTOR 2 Negatively Modulates Pollen Production and Seed Formation in Arabidopsis

2021 ◽  
Vol 12 ◽  
Author(s):  
Yoon Kim ◽  
Sun-Ho Kim ◽  
Dong-Min Shin ◽  
Soo-Hwan Kim
Keyword(s):  
Pollen Grains ◽  
Starch Accumulation ◽  
Bhlh Transcription Factor ◽  
Pollen Production ◽  
Sucrose Transport ◽  
Seed Formation ◽  
Helix Loop Helix ◽  
Knockout Mutants ◽  
Auxin Signalling ◽  
Genes Encoding

ATBS1-INTERACTING FACTOR 2 (AIF2) is a non-DNA-binding basic-helix-loop-helix (bHLH) transcription factor. Here, we demonstrate that AIF2 negatively modulates brassinosteroid (BR)-induced, BRASSINAZOLE RESISTANT 1 (BZR1)-mediated pollen and seed formation. AIF2-overexpressing Arabidopsis plants (AIF2ox) showed defective pollen grains and seed production while two AIF2 knockout mutants, aif2-1 and aif2-1/aif4-1, displayed opposite phenotypes. Genes encoding BZR1-regulated positive factors of seed size determination (SHB1, IKU1, MINI3) were suppressed in AIF2ox and genes for negative factors (AP2 and ARF2) were enhanced. Surprisingly, BZR1-regulated pollen genes such as SPL, MS1, and TDF1 were aberrantly up-regulated in AIF2ox plants. This stage-independent abnormal expression may lead to a retarded and defective progression of microsporogenesis, producing abnormal tetrad microspores and pollen grains with less-effective pollen tube germination. Auxin plays important roles in proper development of flower and seeds: genes for auxin biosynthesis such as TCPs and YUCCAs as well as for positive auxin signalling such as ARFs were suppressed in AIF2ox flowers. Moreover, lipid biosynthesis- and sucrose transport-related genes were repressed, resulting in impaired starch accumulation. Contrarily, sucrose and BR repressed ectopic accumulation of AIF2, thereby increasing silique length and the number of seeds. Taken together, we propose that AIF2 is negatively involved in pollen development and seed formation, and that sucrose- and BR-induced repression of AIF2 positively promotes pollen production and seed formation in Arabidopsis.

scholarly journals Flowering dynamics and pollen production of Laburnum anagyroides Med. under the conditions of south-eastern Poland

2013 ◽  
Vol 57 (2) ◽  
pp. 103-115 ◽  
Author(s):  
Ernest Stawiarz ◽  
Anna Wróblewska
Keyword(s):  
Pollen Grains ◽  
Average Weight ◽  
Pollen Production ◽  
Full Bloom ◽  
Flowering Duration ◽  
The Third ◽  
Laburnum Anagyroides ◽  
Golden Yellow ◽  
Single Flower ◽  
The Common

Abstract A study on the flowering biology and pollen production of the common laburnum (Laburnum anagyroides Med.) was conducted under the conditions of Lublin during the period 2004 - 2006. The flowering of this species began in the second 10-day period of May and lasted for 2.5 - 4 weeks. The flowers of common laburnum are borne in showy golden-yellow pendulous racemes. They develop successively, starting from the base and moving to the tip of an inflorescence. During the growing season, one shrub produces 800 to 3200 racemes, with 14 to 35 flowers in a single raceme. On average, the flowering duration for a raceme was 12.8 days and 8.7 days for a single flower. Throughout the study years, the shrubs proved to be most attractive in the third 10-day period of May when they reached full bloom. The average weight of pollen produced was 6.08 mg per 10 flowers of Laburnum anagyroides, 14.02 mg per raceme, and 26.0 g per shrub. Pollen grains reached average dimensions of 24.01 μm × 24.26 μm.

scholarly journals Effect of high temperature on the reproductive development of chickpea genotypes under controlled environments

2012 ◽  
Vol 39 (12) ◽  
pp. 1009 ◽  
Author(s):  
Viola Devasirvatham ◽  
Pooran M. Gaur ◽  
Nalini Mallikarjuna ◽  
Raju N. Tokachichu ◽  
Richard M. Trethowan ◽  
...  
Keyword(s):  
Heat Stress ◽  
High Temperature ◽  
Pollen Germination ◽  
Pollen Viability ◽  
Pollen Grains ◽  
High Temperature Stress ◽  
Pollen Production ◽  
Seed Number ◽  
Controlled Environments

High temperature during the reproductive stage in chickpea (Cicer arietinum L.) is a major cause of yield loss. The objective of this research was to determine whether that variation can be explained by differences in anther and pollen development under heat stress: the effect of high temperature during the pre- and post-anthesis periods on pollen viability, pollen germination in a medium, pollen germination on the stigma, pollen tube growth and pod set in a heat-tolerant (ICCV 92944) and a heat-sensitive (ICC 5912) genotype was studied. The plants were evaluated under heat stress and non-heat stress conditions in controlled environments. High temperature stress (29/16°C to 40/25°C) was gradually applied at flowering to study pollen viability and stigma receptivity including flower production, pod set and seed number. This was compared with a non-stress treatment (27/16°C). The high temperatures reduced pod set by reducing pollen viability and pollen production per flower. The ICCV 92944 pollen was viable at 35/20°C (41% fertile) and at 40/25°C (13% fertile), whereas ICC 5912 pollen was completely sterile at 35/20°C with no in vitro germination and no germination on the stigma. However, the stigma of ICC 5912 remained receptive at 35/20°C and non-stressed pollen (27/16°C) germinated on it during reciprocal crossing. These data indicate that pollen grains were more sensitive to high temperature than the stigma in chickpea. High temperature also reduced pollen production per flower, % pollen germination, pod set and seed number.

Pollen, Allergens, and Human Health

2019 ◽  
Author(s):  
Rachel N. McInnes
Keyword(s):  
Management Practices ◽  
Dna Analysis ◽  
Pollen Grains ◽  
Health Impact ◽  
Meteorological Conditions ◽  
Day Length ◽  
Allergenic Pollen ◽  
Pollen Production ◽  
The Public ◽  
The Impact

Allergenic pollen is produced by the flowers of a number of trees, grasses, and weeds found throughout the world. Human exposure to such pollen grains can exacerbate pollen-related asthma and allergenic conditions such as allergic rhinitis (hay fever). While allergenic pollen comes from three main groups of plants—certain trees, grasses, and weeds—many people are sensitive to pollen from one or a few taxa only. Weather, climate, and environmental conditions have a significant impact on the levels and varieties of pollen grains present in the air. These allergenic conditions significantly reduce the quality of life of affected individuals and have been shown to have a major economic impact. Pollen production depends on both the current meteorological conditions (including day length, temperature, irradiation, precipitation, and wind speed/direction), and the water availability and other environmental and meteorological conditions experienced in the previous year. The climate affects the types of vegetation and taxa that can grow in a particular location through availability of different habitats. Land-use or land management is also crucial, and so this field of study has implications for vegetation management practices and policy. Given the influential effects of weather and climate on pollen, and the significant health impacts globally, the total effect of any future environmental and climatic changes on aeroallergen production and spread will be significant. The overall impact of climate change on pollen production and spread remains highly uncertain, and there is a need for further understanding of pollen-related health impact information. There are a number of ways air quality interacts with the impact of pollen. Further understanding of the risks of co-exposure to both pollen and air pollutants is needed to better inform public health policy. Furthermore, thunderstorms have been linked to asthma epidemics, especially during the grass pollen seasons. It is thought that allergenic pollen plays a role in this “thunderstorm asthma.” To reduce the exposure to, or impact from, pollen grains in the air, a number of adaptation and mitigation options may be adopted. Many of these would need to be done either through policy changes, or at a local or regional level, although some can be done by individuals to minimize their exposure to pollen they are sensitive to. Improved aeroallergen forecast models could be developed to provide detailed taxon-specific, localized information to the public. One challenge will be combining the many different sources of aeroallergen data that are likely to become available in future into numerical forecast systems. Examples of these potential inputs are automated observations of aeroallergens, real-time phenological observations and remote sensing of vegetation, social sensing, DNA analysis of specific aeroallergens, and data from symptom trackers or personal monitors. All of these have the potential to improve the forecasts and information available to the public.

Self-Incompatibility, Protandry, Pollen Production and Pollen Longevity in Banksia menziesii

1991 ◽  
Vol 39 (5) ◽  
pp. 497 ◽  
Author(s):  
M Ramsey ◽  
G Vaughton
Keyword(s):  
Natural Population ◽  
Pollen Grains ◽  
Reproductive Traits ◽  
Pollen Production ◽  
Self Incompatibility ◽  
Cross Pollination ◽  
Pollen Vectors ◽  
Pollen Longevity ◽  
Pollen:Ovule Ratio

Controlled self- and cross-pollination indicated that a natural population of Banksia menziesii (Proteaceae) was self-incompatible. Flowers were protandrous. Deposition of pollen into the stigmatic cavity was regulated by opening of the stigmatic groove. Stigmatic grooves opened 24-48 h after the flowers opened. Pollen production was high and the pollen:ovule ratio was approximately 10000. Over 90% of pollen grains were viable when flowers first opened. Viability decreased rapidly with time and most pollen was inviable within 24 h. These results indicate that B. menziesii requires pollen vectors to produce seed and suggest that pollinators may have influenced the evolution of the reproductive traits that were examined.

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