AFRICAN MISTLETOES (Tapinanthus spp): BIOLOGY AND PATHOLOGY.

UNIVERSITY OF NIGERIA, NSUKKA.

DEPARTMENT OF PLANT SCIENCE AND BIOTECHNOLOGY.

NAME: OHAKAWA, NKECHI. C.

REG. NO: 2009/169214.

COURSE: BOT 482(SEMINAR).

TOPIC: AFRICAN MISTLETOES (Tapinanthus spp): BIOLOGY AND PATHOLOGY.

DATE: 20^TH MARCH, 2013.

SUMMARY.

     African mistletoes are partial parasites of plants; they have a wide range of host plants which are of economic value like Irvingia gabonensis, Persea americana and Theobroma cacao (3, 13, 15). They can be defined as chlorophyllous semi-parasites that parasitize the stems of trees by means of haustoria for absorption of nutrients and water. These haustoria come in contact with the xylem and vascular bundles of the plants thereby causing a blockage of the flow of water and nutrient to other parts of the plants (1, 6).

     African mistletoe is a parasitic plant which grows mostly on woody trees. The leaves are yellow-green in color and the berries are whitish, opaque and sticky. The mode of dispersal of the sticky seeds of Tapinanthus is by birds and wind which dry on exposure to air and germinates on contact with the host, penetration and proliferation of the haustoria leads to the death of adjacent host tissues (2). The host-parasite relationship is in such a way that the host provides the parasite with water and nutrient while the parasite carries out photosynthesis (5). The haustorium grows through the host xylem and phloem causing the host to die gradually by desiccation (2, 9).   

      African mistletoe belongs to the family Loranthaceae and it is of two species namely: Tapinanthus bangwensis and Tapinanthus globiferus .T.bangwensis produces red flowers while T. globiferus produces yellow flowers (7, 11).

     Tapinanthus species infection causes a noticeable decrease in vigor of the branches above the point of attachment of the parasite, followed by galls, branch bending and sometimes even death may occur.  Infection of mistletoe affects the seed yield, growth of shoot, alters the wood quality of the infected plant (4, 14). Abiotic factors such as moisture stress, pest infection and low tree density increase the incidence of parasitic plants (9). Mistletoes are serious agents of deforestation and erosion. Host-parasite compatibility may be due to physiological factors present in the host which promotes or reduces the growth of the parasite, age or host abundance (8, 10). Spread of mistletoe can be controlled by regular pruning of infected branches, cutting, removing the shoots, chemical growth regulators etc. Mistletoes are distributed in various parts of the world like Nigeria, Togo, Ghana and Europe and it is an excellent medicinal plant (12).

REFERENCES.

1.      Bassey. M. E (2012). Phytochemical investigation of Tapinanthus globiferus (loranthaceae) from two hosts. International Journal of Chemical, Environmental and Pharmaceutical Research 3, 2:174. 

2.      Bassey, P. and Sowemimo, A (2012). Biological activities of Tapinanthus bangwensis leaves. African Journal of Biotechnology 11: 13821.

3.      Beryl, B. S and Molly C.O (1986). Economic Botany. Mc Graw-Hillbook Company, New York 640pp

4.      Boussim, I. J (2002). Les Phanerogames Parasites du Burkina Faso. Sciences Naturalles, 1: 285-380.

5.      Boussim, I. J., Guiko, S., Tuquet, C and Salle, G (2004). Mistletoe of the Agroforestry Parklands of Burkina Faso. Agroforest System, 60: 39-49.

6.      Dawson, T. E., King, E. J and Ehleringer, J. R (1990). Xylem-tapping mistletoe: Inferences from a Non-Destructive Morphological Index of Age. American Journal of Botany, 77: 573-583.

7.      Engler and Krause, K (1971). Establishment of in-vitro cultures of Tapinanthus bangwensis and the Effects of Sugars on Growth. Annals of Botany 35 (5): 1113-1129.

8.      Lopez, B and Ornelas J. F (1999). Host Compatibility of Mistletoe. American Journal of Botany 1-5.

9.      Lopez, B., Ornelas J. N and Garcia Franco J. G (2002). Mistletoe Infection of Trees. Forest Ecology and Management 164: 293-302.

10.   Martinez, C., Silva, A and Medel, R (1996). Seed Dispersers as Disease Vectors: Bird Transmission of Mistletoe Seeds to Plant Hosts. Ecological Society of America 77: 3.

11.   Norton D. A (1997). Distribution and Population of the Loranthaceous Mistletoe. New Zealand Journal of Botany 35: 323-336.

12.    Onyeke, C. C., Ugwuoke, K. I., Osayi, E. E and Atama, C. I (2010). African Mistletoes: Infection on some Economic Plants in Nsukka, Enugu State. Proceedings on the Sixth National Conference of the Society for Occupational Safety and Environmental Health (SOSEH). 65-73pp.

13.   Room P. M (1971). Physiological aspects of the relationship between Theobroma cacao (cocoa) and Tapinanthus bangwensis (mistletoe). Annuals of Botany Journal 35,169-174.

14.   Ukwueze, S. E and Osadebe, P. O (2012). Determination of Anti-fungal Properties of the African Mistletoe. International Journal of Pharmacy and Biological Science, 3:1.

15.   Watson, D. M (2001). A Keystone Resource in Forests. Annual Review of Ecology and Systematics 32: 219-249.