Role of primary metabolites in plant defense against pathogens.

Summary Allelopathy plays an important role in the agroecosys-tems leading to a wide array of interactions between crop-crop, crop-weed and tree-crops. Generally, these interactions are harmful to the receiver plants but provide a selective benefit to the donor. Soil microbes play a key role in determining such interactions as they not only alter the nature of allelopathic interactions but also modify the expression of allelochemicals. Soil sickness problem in the croplands could also be attributed to the allelopathic property or even the autotoxicity. The allelochemicals released largely by the plant residues that are left in the fields after the harvest of crops add to the multifarious problems. If properly managed, these residues could be used for controlling weeds and pests. As is true for any chemical based response, allelopathic interactions are also concentration specific. The promotory functions that are inbuilt need to be worked out and exploited. Now a days allelopathic interactions, in general,...

Allelopathy in agroecosystems: an overview.

The effect of UV irradiation on the levels of the flavanone, naringin, and the polymethoxyflavone, tangeretin, in the peel of Citrus aurantium fruits is described, as changes in the synthesis and/or accumulation of these compounds after infection with Penicillium digitatum. The growth of P. digitatum on previously irradiated fruit was reduced by up to 45%. Changes in flavonoid levels were detected, associated with inhibition of fungus growth, the naringin content falling by 69% and tangeretin levels increasing by 70%. The possible participation of naringin and tangeretin in the defence mechanism of this Citrus species is discussed.

H. Hindorf

Papers

An effective treatment of legume seeds with flavonoids and isoflavonoids against storage fungi of the genus Aspergillus