Pollen allelopathy

Murphy, S.D. (1999). Is there a role for pollen allelopathy in biological control of weeds. In Allelopathy Update, (Ed., S.S. Narwal) Vol. 2 321-332. Science Publishers, Enfield, Plymouth, USA. 

Flow cytometry is an alternative for the studies of pollen allelopathy that offers a more accurate census and a wider range of sizes of pollen that can be analyzed, though it is much more expensive, in terms of the cost and operation of the equipment. It is in fact expensive enough (typically several hundred thousand dollars for the equipment), that the idea has been vetted but few were willing to risk the expense for simply counting as opposed to more sophisticated uses to investigate cellular physiology. 

Just as a Coulter Counter or a flow cytometer can automate or at least increase efficiency in counting heterospecific pollen transfer, use of artificial germination media still is an effective method of screening for pollen allelopathy. The fundamental approach recommended has not changed much in the last decade, i.e. sequentially dilute extracts from non-macerated... 

Murphy, S. D. (2001). Field testing for pollen allelopathy A review. Journal of Chemical Ecology 26 2155-2172... 

Murphy, S. D. and Aarssen, L. W. (1989). Pollen allelopathy among sympatric grassland species In vitro evidence in Phleum pratense L. New Phytologist 112 295-305. 

Roshchina, V. V. (2001). Molecular-cellular mechanisms in pollen allelopathy. 

Roshchina, V. V. and Melnikova, E. V. (1996). Microspectrofluorometry A new technique to study pollen allelopathy. Allelopathy Journal 3 51-58 Roshchina, V. V. and Melnikova, E. V. (1998). Allelopathy and plant generative cells Participation of acetylcholine and histamine in signaling interactions of pollen and pistil. Allelopathy Journal 5 171-182 Roshchina, V.V. and Melnikova, E. V. (1999). Microspectrofluorometry of intact secreting cells applied to allelopathy. ln Principles and Practices in Plant Ecology., Inderjit, K. M. M. Dakshini, and C. L. Foy (eds) pp. 99-126. CRC Press, Boca Raton, Florida, USA. 

Shapiro, H. M. (2003). Practical Flow Cytometery. Wiley-Liss, New YorkUSA Sukhada, K.D. and Jayachandra (1980a). Pollen allelopathy - a new phenomenon. 

Pollen allelopathy is phenomenon when pollen chemicals (e.g., phenols, terpenoids, sesquiterpene lactones, etc.) inhibit sexual reproduction in heterospecific individuals due to influencing of fertilization (Murphy 1992). The phenomenon includes excretion of signaling compounds from the donor cell (pollens, pistil stigma), recognition of a specific signal, transmission of information (pollen), and the development of a characteristic response in the acceptor cell. The possible mechanism of the effect was described in Roshchina (2001). 

Pollen allelopathy can find utilization in field cultivations that could contain pollen of allelopathic crops or weeds. Pollen allelopathy could be an effective method for annual weed control that reproduce, at least in part, via wind pollination and flower concurrently with the allelopathic species. The effects of allelopathy should result in the loss of genetic variation and so in reduction of reproductive ability, but some plants are probably able to detoxify the pollen allelochemicals (Murphy and Aarssen 1995a, b). Murphy and Aarssen (1989) suggested possible delaying of weed flowering at later, less favorable times of the season or diurnal period, so decrease in weed pressure. However, infestation by perennial weeds can worsen due to compensation of pollen allelopathy through increase in the formation of rhizomes. 

The main advantage of pollen allelopathy is that allelochemicals occur in a natural form, i.e., pollen grains and are biologically active at low doses (10 grains mm-2 on stigmas) (Murphy 2001). hi case of pollen allelopathy, autotoxicity was not established (Murphy and Aarssen 1995a). 

Newly investigated pollen allelopathy could effectively reduce the reproductive ability of wind pollination of annual weeds. Pollen of allelopathic species could be artificially dusted on the stigmatic surface of other plants. This phenomenon needs study and field testing yet. 

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... 

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