Pollen biology of the serpentine-endemic Orobanche nowackiana (Orobanchaceae) from Albania

The holoparasite flowering plant Orobanche nowackiana Markgr. is a rare endemic plant that parasitises the Ni hyperaccumulator species Alyssum murale Waldst. and Kit. in Komjan Mt. (Albania). The purpose of this study was to establish baseline data concerning aspects of its pollen biology. To achieve this goal three objectives were addressed: (1) describe pollen morphology; (2) study pollen production and fertility/sterility; (3) study the localisation of metals in anthers and pollen. Pollen morphology was investigated with light microscope and scanning electron microscope (SEM) observations. The pollen grains are 3-colpate, most often oblate-spheroidal, with long colpi reaching the poles. The ornamentation is microreticulate. The anther and pollen grains were micromorphologically analysed by SEM coupled with an energy-dispersive X-ray probe (SEM-EDX). Low concentration of Ni was recorded for anthers (0.38%) and pollen (0.1–5.6%). Variation in pollen production was found for the flowers of the same individual. The mean pollen production per flower and stamen was 59365 and 14938 pollen grains respectively. The sterile pollen was above the limit considered as a normal abortion and was between 10.1 and 38.0%. From a palynological point of view our results are important for taxonomy and support keeping the species in the genus Phelipanche.

Allergenic pollen emissions from vegetation—threats and prevention

Allergic diseases are caused by hypersensitivity of the immune system to a certain environmental exposure. Many different agents may induce an allergic reaction. This chapter concerns reactions to pollen. Although allergies to animals, for example dogs and cats, may be considered as part of nature-induced allergy, the focus here is on vegetation. Allergic reactions to pollen depend on the type of pollen, biological properties, location, and individual factors. Changes in our immune systems, our living environments and lifestyles, and climate change may play a role in the increasing prevalence of pollen allergies. This chapter contains three major sections: first, the basics of pollen biology are outlined; secondly, pollen’s impact on human health are introduced; and finally, the chapter includes a section on how practitioners and policymakers can plan our cities to be green, and yet limited in allergenic exposure.

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 &amp;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>

Regulation of fertilization and early seed development

Plant reproduction meetings often deal either with pre-fertilization processes such as flowering and pollen biology or post-fertilization processes such as embryogenesis and seed development. The Biochemical Society Focused Meeting entitled ‘Regulation of Fertilization and Early Seed Development’ was organized to close this gap and to discuss mechanistic similarities and future research directions in the reproductive processes shortly before, during and after fertilization. As an outcome of the workshop, invited speakers and a few selected oral communication presenters contributed focused reviews and technical articles for this issue of Biochemical Society Transactions. We provide here a short overview of the contents and highlights of the various articles.

Reproductive biology of seven taxa of Magnolia L. in the south of Russian Far East

This paper presents the phenology of seven taxa of the genus Magnolia L., pollen biology on germination and storage conditions, seed productivity, germinating ability of seeds and its dependence on stratification and germination conditions. It has been found that M. kobus DC, M. kobus var. boreales Sarg., M. obovata Thurb., M. officinalis Rehd. et Wils., M. salicifolia (Sieb. et Zucc.) Maxim., M. sieboldii K. Koch. and M. tripetala L. in cultivated condition produce pollen at a low viability rate (9.4 - 31.7%). Real seed productivity of the taxa being studied is less than their potential productivity. However, M. obovata, M. officinalis and M. tripetala are characterized by high seed germinating ability, up to 94%. Optimal germination conditions for seeds of M. tripetala, M. officinalis and M. obovata require protected ground (greenhouse) and stratification at 4ºC during 30 days. The high germinating ability of M. sieboldii seeds in the open ground is explained by stratification duration and temperature required for this species. Sarcotesta effects on higher seed germinating ability have been observed in M. obovata only.DOI: http://dx.doi.org/10.3329/bjpt.v20i2.17390Bangladesh J. Plant Taxon. 20(2): 163-170, 2013

Pollen Biology of Calligonum mongolicum in the Middle Reaches of Heihe River

The pollen–ovule ratios, pollen fertility rate, pollen viability and longevity, pollen histochemistry of Calligonum mongolicum flowers were determined in the field by the middle reaches of Heihe River. The main results were as follows: Calligonum mongolicum is completely fertile and has starchy pollen. Anthers matured heterotypically. The pollen longevity was about 10h. The pollen viability was higher than 70% at the beginning of anthesis on sunny days. No difference in the pollen production of single anther was found between different flower morphes, but significant difference was in that of single flower. The pollen-ovule ratios of different morph flowers were 1625±125, 1750±177, 1500±102, 1563±120, 1875±72. Pollen–ovule ratios (P/O) reveal that C. mongolicum is facultative autogamous.