Indigenous arbuscular mycorrhizal fungi in oil palm soils in Colombia

Abstract

Generally monocultures have replaced tropical forests and other ecosystems, causing big changes and little is known about the influence of the practice of monoculture in density and biodiversity of mycorrhizal fungi (AMF) species. Spore production is highly depend of physiologycal parameters of the AMF and on environmental conditions, however it is known that in nutrient-poor soils of the humid tropics many plants are obligate mycotrophs or ecologically dependent on AMF. In Oil palm (Elaeis guineensis Jacq), the limited development of their root system and field observations of high levels of mycorrhizal colonization, suggest that this crop benefits greatly from the symbiosis.[1]Isolation of soil spores and subsequent microscopic examination is a routine procedure in the recognition of AMF species, however the study of walls by light microscopy is a difficult task; interpretation depends on several factors such as the type of microscope and lighting mounting means and observer experience.Based on the morphological characteristics of the AMF described approximately 200 species (2).As a complement to morphological studies AMF wall light microscopy has been used transmission electron microscopy (TEM) and scanning electron microscopy (SEM), however the publications in this field are limited. Another limitation of morphologycal identification is the fact that field- collected spores are often parasitized or degraded and therefore unidentifiable. A methodology for increased healthy spores are AMF trap cultures ,soil samples from the field site are brought into contact with suitable plant hosts of AMF under controlled conditions in order to propagate the species, additionally the plant species used in the trap cultures may have an influence on which AMF are detected , aditionaly the molecular identification is a good tool for the identification of AMF, almost all identification systems for AMF are based on the ribosomal DNA (rDNA) , this is highly polymorphic in single spores of AMF. The aim of this study was to determine the initial density of native mycorrhizal fungi spores in soils of oil palm monocultures, and the identification of AMF species increased in trap cultures under controlled greenhouse conditions . Mycorrhizal fungi spores were identified using optical and scanning microscopy, and molecular analysis was useful for identifying some species of Glomus.