In pollen

Keijzer, C.J. (1983). Hydration changes during anther development. In Pollen Biology and Implications for Plant Breeding, ed. N.L. Matching F.A. Oha-viane, pp. 199-202. Elsevier. 

Xiao, C.-M. Mascarenhas, J.P. (1985). High temperature-induced thermotolerance in pollen tubes of Tradescantia and heat-shock protein. Plant Physiology, 78, 887-9. 

Rak S. Lowhagen O, Venge P The effect of immunotherapy on bronchial hyperresponsiveness and eosinophil cationic protein in pollen-allergic patients. J Allergy Chn Immunol 1988 82 470-480. 

Each plant tissue tends to have an obviously distinctive profile of flavonoids. The flavonoid content can reach about 0.5% in pollen, 10% in propolis, and about 6 mg/kg in honey. Havonoid aglycones appear to be present only in propolis and honey, while pollen contains flavanols in herosidic forms. The flavonoids in honey and propolis have been identified as flavanones and flavanones/flavanols (Campos et ah, 1990). The antimi-crobially active flavanone pinocembrine was foimd to be a major flavonoid in honey (Bogdanov, 1989). Amiot et ah (1989) studied two blossom and two honeydew Swiss honey samples and foimd that pinocembrine was the main flavonoid. Pinocembrine concentration varied between 2 and 3 mg/kg (Bogdanov, 1989). Berahia et ah (1993) analyzed sunflower honey samples and detected six flavone/flavols, four flavanone/ flavols, and pinocembrin, of which pinocembrin is the main flavonoid. The flavonoids in sunflower honey and propolis were characterized and assessed for their effects on hepatic drug-metabolizing enzymes and benzo [fl]pyrene-DNA adduct formation (Sabatier et ah, 1992 Siess et ah, 1996). 

Coffey, M. F. and Breen, J. (1997). Seasonal variation in pollen and nectar sources of honey bees in Ireland. J. Apicult. Res. 36, 63-76. 

Roshchina V.V. (2001b). Molecular-cellular mechanisms in pollen alllelopathy. Allelopathy Journal 8 11-28. 

One key issue is why Phleum pretense does not exhibit autotoxicity. Its pollen does fluoresce at 520 nm on conspecific stigma but it is possible that this masks more subtle changes in pollen chemistry or metabolism and detoxification of conspecific allelochemicals, in situ. Therefore, it is yet to be elucidated if the specific mechanism prevents autotoxicity though the... 

Based on previous experiments in tobacco and Arabidopsis, the USP promoter fragment we used was considered to be highly seed specific. However, thorough examination of the field-grown pea plants revealed some promoter activity in pollen, albeit 100-fold lower than the activity seen in seeds (Fig. 12.3). To test whether or not the pollen expression is restricted to pea, we also examined pollen from transgenic... 

Rizvi SJH, Mishra GP, Rizvi V (1989) AUelopathic effects of nicotine on maize I. Its possible importance in crop rotation. Plant Soil 116 289-291 Roshchina VV (2001) Molecular-cellular mechanisms in pollen allelopathy. Allelopathy J 8 11-28 Roth CM, Shroyer JP, Paulsen GM (2000) Allelopathy of sorghum on wheat under several tillage systems. Agron J 92 855-860... 

The weevils do not linger to feed and breed in seed cones as they do in pollen cones, even though starch is plentiful here as well. This behavioral difference is not yet completely understood, but it seems that the cones of female plants contain an active poison called beta-(methylamino)alanine (BMAA). This substance is a recognized neurotoxin for mammals and is believed to affect insects as well. The male plants pollen cones also contain BMAA, but in a bound form that renders it harmless, allowing the weevils to nest and feed with impunity. In contrast, seed cones contain free toxic BMAA that presumably repels weevils and causes them to depart after quick examination and inadvertent pollination. 

Androgenic compounds occur in various plants. Celery stalks and parsnip roots contain trace amounts of androstenedione (Fig. 11.12), the same compound found in boar odor (Claus and Hoppen, 1979). Testosterone is also found in pollen of Scots pine Pinus sylvestris). 

TABLE III. Relative Stability of Oxytetracycline in Pollen Patty Bee Diets (% Recovered)... 

Present Label Implicitly Applies to Harvested Pollen. For beekeepers who use oxytetracycline for medication, the present label (Table I) is explicit in defining the proper use and precautions that need to be followed when honey is to be harvested and marketed for human consumption. Presumably the label implicitly applies to pollen collected for human consumption as well. This does, however, pose an interesting question - if fresh pollens were collected in pollen traps placed at the hive entrance of medicated colonies before the 4 week restriction elapsed, as stated on the use label for collecting marketable honey, would the oxytetracycline be transferred by the honey bee to the pollen. To answer the question field colonies were medicated by feeding freshly prepared solutions of medicated sugar syrup for several weeks at recommended and twice recommended levels. Immediately at the end of medication, and every 3 to 4 days thereafter, pollen traps were sampled and emptied to trap samples of pollen freshly collected by the foraging bees. 

CS137 Yamane, H., H. AbeandN. Takahashi. CS147 Jasmonc acid and methyl jasmonate in pollens and anthers of three Camelliaspecies. Plant Cell Physiol CS148 1982 23 1125-1127. 

Flavonoids in Pollen, and Their Role in Plant Sexual... 

Alternative hypotheses for pollen pigments hold that flavonoids are involved in pollen-style incompatibility relationships via pollen germination, or else serve as growth regulators for pollen tube development. Certain flavonoids have also been postulated to ameliorate the effects of heat stress during fertilization. 

In order to understand the role of flavonoids in pollen, flavonoid-deficient mutants have been produced through artificial methods, such as cosuppression, antisense expression, chemical mutagenesis, and ionizing radiation. Examples include and A. thali-... 

Song, K.S. et al., Phenolic function in pollen growth in Arabidopsis thaliana, Acta Hortic., 447, 223,... 

Wakelin, A.M., Biochemistry and Inheritance of Pollen/Petal Colour Mutants in Californian Poppy — Investigating the Role of Carotenoid Pigments in Pollen, PhD thesis, Lincoln University, New Zealand, 2001. 

Evolutionary shifts from reward to deception in pollen flowers. In The Pollination of Flowers by Insects, ed. A. J. Richards, pp. 89-96. London Academic Press. 

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