Characterization of Ectomycorrhizal species through molecular biology tools and morphotyping

Mycorrhizae are mutualistic associations between fungi and plant roots. These symbiotic associations are abundant and occur in 75 to 80 % of plants. Ectomycorrhizal fungi are very important in ecosystems, because their mutualistic association with plants of different species helps nutrients and water absorption, as well as protection of the host plant against pathogens and abiotic stresses. Most ectomycorrhizal fungi belong to the Basidiomycota class, such as the following genera: Amanita, Hebeloma, Hysterangium, Laccaria, Lactarius, Rhizopogon, Russula, Scleroderma, Suillus, Tricholoma, among others. Morphological studies on ectomycorrhizae report important results in understanding the species biodiversity. However, the use of molecular biology nowadays is indispensable. Among the various molecular tools available, there is consensus about the use of tools based on sequencing of the Internal Transcribed Spacer (ITS) of fungi rDNA, aiding in species characterization and construction of phylogenetic studies. The ITS region is of easy amplification, it has multicopy nature and enables differentiation between species. The objective of this study was to show that the use of molecular biology tools associated with morphotyping to characterize species of ectomycorrhizae is more effective than when they are used on their own.

Characterization of Ectomycorrhizal species through molecular biology tools and morphotyping

Mycorrhizae are mutualistic associations between fungi and plant roots. These symbiotic associations are abundant and occur in 75 to 80 % of plants. Ectomycorrhizal fungi are very important in ecosystems, because their mutualistic association with plants of different species helps nutrients and water absorption, as well as protection of the host plant against pathogens and abiotic stresses. Most ectomycorrhizal fungi belong to the Basidiomycota class, such as the following genera: Amanita, Hebeloma, Hysterangium, Laccaria, Lactarius, Rhizopogon, Russula, Scleroderma, Suillus, Tricholoma, among others. Morphological studies on ectomycorrhizae report important results in understanding the species biodiversity. However, the use of molecular biology nowadays is indispensable. Among the various molecular tools available, there is consensus about the use of tools based on sequencing of the Internal Transcribed Spacer (ITS) of fungi rDNA, aiding in species characterization and construction of phylogenetic studies. The ITS region is of easy amplification, it has multicopy nature and enables differentiation between species. The objective of this study was to show that the use of molecular biology tools associated with morphotyping to characterize species of ectomycorrhizae is more effective than when they are used on their own.(AU)

Early changes in arbuscular mycorrhiza development in sugarcane under two harvest management systems

Sugarcane (Saccharum spp.) is grown on over 8 million ha in Brazil and is used to produce ethanol and sugar. Some sugarcane fields are burned to facilitate harvesting, which can affect the soil microbial community. However, whether sugarcane pre-harvest burning affects the community of arbuscular mycorrhizal fungi (AMF) and symbioses development is not known. In this study, we investigated the early impacts of harvest management on AMF spore communities and root colonization in three sugarcane varieties, under two harvest management systems (no-burning and pre-harvest burning). Soil and root samples were collected in the field after the first harvest of sugarcane varieties SP813250, SP801842, and RB72454, and AMF species were identified based on spore morphology. Diversity indices were determined based on spore populations and root colonization determined as an indicator of symbioses development. Based on the diversity indices, spore number and species occurrence in soil, no significant differences were observed among the AMF communities, regardless of harvest management type, sugarcane variety or interactions between harvest management type and sugarcane variety. However, mycorrhiza development was stimulated in sugarcane under the no-burning management system. Our data suggest that the sugarcane harvest management system may cause early changes in arbuscular mycorrhiza development.

Arbuscular mycorrhizal fungi in saline soils: vertical distribution at different soil depth

Arbuscular mycorrhizal fungi (AMF) colonize land plants in every ecosystem, even extreme conditions such as saline soils. In the present work we report for the first time the mycorrhizal status and the vertical fungal distribution of AMF spores present in the rhizospheric soil samples of four species of Chenopodiaceae (Allenrolfea patagonica, Atriplex argentina, Heterostachys ritteriana and Suaeda divaricata) at five different depths in two saline of central Argentina. Roots showed medium, low or no colonization (0-50%). Nineteen morphologically distinctive AMF species were recovered. The number of AMF spores ranged between 3 and 1162 per 100 g dry soil, and AMF spore number decreased as depth increased at both sites. The highest spore number was recorded in the upper soil depth (0-10 cm) and in S. divaricata. Depending of the host plant, some AMF species sporulated mainly in the deep soil layers (Glomus magnicaule in Allenrolfea patagonica, Septoglomus aff. constrictum in Atriplex argentina), others mainly in the top layers (G. brohultti in Atriplex argentina and Septoglomus aff. constrictum in Allenrolfea patagonica). Although the low percentages of colonization or lack of it, our results show a moderate diversity of AMF associated to the species of Chenopodiaceae investigated in this study. The taxonomical diversity reveals that AMF are adapted to extreme environmental conditions from saline soils of central Argentina.