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Chemistry of Desmodium
root exudate and Striga control: research status and prospects
A. Hassanali, M.K. Tsanuo,
A.M. Hooper, Z. Khan, F. Kaberia, J. Pickett & L. Wadhams
Two
types of isoflavanoid constituents have been found in compositionally
complex root exudates of Desmodium
uncinatum: germination stimulants and haustorium inhibitors.
The combined action of these allelochemics provide a novel, in
situ mechanism of continuously depleting Striga
seeds from the soil, so far demonstrated in experimental Desmodium-maize
intercrops. Some of the
allelochemics have been isolated and characterized.
The differences in activities of these compounds suggest
relatively specific structural requirements for germination stimulatory
and haustorium inhibitory activities.
The implications for screening for Desmodium-type Striga
suppression attribute and for a biotechnological approach to
transferring this attribute to other crops will be highlighted.
Specifically, the presentation will address the following topics:
1) the diversity of Desmodium root chemistry and role, if any, in Striga suppression; 2) the occurrence of isoflavanoid biochemistry
in Leguminosae and 3) other families and probability of finding
Desmodium-type secondary compounds; and prospects of transferring
Desmodium biochemical attributes to other crops.
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