Striga parasitism

Unidentified Stimulators. Growth-inhibitory materials in, or secreted by, plants have for the most part been emphasized in this paper. However, root secretions of many plants also contain constituents required for the germination of seeds of angiospermous root parasites (Striga, Orobanche, Alectra, and Sopubia genera). This phenomenon has been reviewed by Brown (17). Striga asiatica was identified for the first time in the western hemisphere in 1956 in two... 

Matusova, R. et ah, The strigolactone germination stimulants of the plant-parasitic Striga and Orobanche spp. are derived from the carotenoid pathway, Plant Physiol. 139, 920, 2005. 

Strigol is a natural product with unusually strong properties as a germination stimulant for parasitic weeds of the genera Striga (witchweed) and Orobanche (broomrape). 

Allelopathy found hopeful utilization in plant protection against parasite weeds. The main world parasitic species are the witchweeds (Striga spp.), broomrapes (Orobanche spp.), and eventually dodder (Cuscuta spp.). Witchweeds and broom-rapes attack many economically important crops especially throughout the semi-arid regions. Early detection of parasitic weed infestation and protection is difficult because of the growth habit of a root parasite and huge production of dust-like seeds viable up to 20 years (Kebreab and Murdoch 1999). 

R. Brown and coworkers observed that seeds of Striga, known as witchweed, a semi-parasitic plant of grasses and corn, germinated only in the presence of root exudates from the living host. They isolated the sirupy exudate, [VJ > + 20° (water), resembling a pentose, but did not specifically identify the active substance. A study of many carbohydrates, mostly pentoses, showed that only D-ihreo-pentulose, C 3) — 32° (water), had the required activity L-[Pg.416]

Worldwide, the competitive effect of weeds causes a 10% loss in agricultural production. Yield losses in rice and other grass crops in West Africa have been reported to range from 28-100% if weeds such as witchweed (Striga hermonthica) -a parasitic weed-are not controlled the greatest reductions occur on nutrient-poor soils. Left unchecked, weeds cause dramatic reductions in food production that eventually can... 

Butler, L.G Chemical communication between the parasitic weed Striga and its crop host. A new dimension of allelochemistry. In Allelopathy Organism, Processes and Application. Inderjit, Dakshini K.M.M., Einhellig, F.A. eds. ACS Symposium Series Washington, DC 1995 582 158-168. 

Ethylene is a potent inductor of Striga spp. germination.26 It has been hypothesized as a possible mechanism for parasitic seed germination that attachment of the inductor to the receptor s site triggers a cascade of biosynthetic reactions leading to the synthesis of the enzymes necessary for ethylene production.12... 

The continuous search for germination inductors to control parasitic weeds has led to testing a great variety of natural products. Some positive results have been obtained for Striga with compounds such as the coumarin scopoletin (11), the... 

Verkleif, J. A. C., and Zwanenburg, B. 1999. Dose-response of seeds of the parasitic weeds Striga and Orobanche toward the synthetic germination stimulants GR24 and Nijmegen 1. J. Agric. Food Chem. 47, 1705-1710... 

Musselman, L. J. 1980. The biology of Striga, Orobanche, and other root-parasitic weeds. Annu. Rev. Phytopathol. 18, 463-489... 

---