Allelopathic interactions in mycorrhizal associations

Mycorrhiza is a symbiotic association between the plant roots and certain soil fungi: Arbuscular Mycorrhizae (AM) and Ectomycorrhizae (ECM) are two most common types of these fungi. AM are common in agricultural crops and weeds, while ECM are,associated with trees. In mycorrhizal relationships, there is bidirectional movement of nutrients. In allelopathy, the living or dead plants release allelochemicals, which mostly exert negative effects on the neighbour plants and. adversely affect the mycorrhizal colonization. The plants of Brassicaceae and Chenopodiaceae are non-mycorrhizal, because of exudation of specific allelochemicals from their roots. These non-host species exhibit negative effect on mycorrhizal colonization of plants growing in their vicinity and also on plant species cultivated after their harvest. AM inoculations enhance the crop growth by alleviating the allelopathic stress possibly through increased nutrient uptake. The ECM often experience the chemical stress from forest floor allelochemicals. ECM fungi are able to alleviate the toxic effects of allelochemicals in host plants through detoxification of allelochemicals and enhanced nutrient uptake. The allelopathic stress alleviating potential of mycorrhizal fungi may be best exploited by selecting well-adopted mycorrhizal species in different habitats.