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Abstract The objective of this study was to determine the structure, diversity, composition and drivers of AMF communities in succession areas of Atlantic Forest. Soil and root samples were collected in three natural ecosystems (mature rainforests, early and late secondary forests) with three areas on each ecosystem. In total, 38 AMF taxa were identified in field samples and three more in trap cultures with a greater richness of Acaulospora and Glomus. Based on a richness estimator, 70% of the AMF species were identified. Highest rates of root colonization and number of glomerospores were recorded in the early secondary forest. AMF species diversity differed between early and late forests. The main drivers of AMF distribution were coarse and fine sand, silt, Al, P, Na, pH and base saturation. The greatest number of exclusive species was recorded in the mature rainforests. The distribution of AMF communities was influenced by different successional stages and some soil attributes.

The Seasonally Dry Tropical Forests (SDTF), distributed from Mexico to northern Argentina, are habitat to a unique biodiversity. Among these forests, the Caatinga stands out, occupying a large part of the Brazilian Northeast and is subject to cycles of anthropic disturbance and abandonment of exploited areas. Understanding how microbial communities respond to environmental changes is crucial, especially considering the various ecosystem services provided by microorganisms. Among soil microorganisms, arbuscular mycorrhizal fungi (AMF) play a significant role in the maintenance of terrestrial ecosystems. In this study, we aimed to evaluate the structure, composition, and distribution of AMF assemblages, as well as their main drivers, in regeneration areas of the Caatinga. Soil samples were collected in the Catimbau National Park (Pernambuco State), including an old-growth forest representing undisturbed areas, and in early, intermediate, and late regeneration areas. The composition of AMF assemblages differed among regenerating areas and old-growth forest, but their distribution is not related and conditioned to plant assemblages. Instead, soil properties and rainfall are the main factors structuring these assemblages in SDTF. A total of 83 taxa of AMF were identified. Glomus and Acaulospora , which exhibit respectively ruderal and stress-tolerant life strategies were the most abundant genera. The highest number of unique AMF species was recorded in the old-growth forest, contrasting with the late regeneration areas which had the lowest number. The results showed that deterministic processes (soil and rainfall) are structuring the AMF assemblages in areas under regeneration process in SDTF. Plants and AMF do not recover simultaneously over the evaluated regeneration times. • Rainfall and soil attributes drive AMF community structure in Dry Tropical Forests. • Plants and AMF do not recover simultaneously over the regeneration time in the studied areas. • AMF communities composition from old-growth forests differs from those of regeneration stages. [ABSTRACT FROM AUTHOR]

The use of microorganisms aiming to improve the availability of nutrients for plants is an important and necessary practice for agriculture. Thus, studies on the AMF occurrence in the brazilian northeastern and efficiency tests using native plants in the region have been intensified on recent decades. Aiming to determine the most probable number (MPN) of infective propagules in the area with native vegetation on the semi-arid region of Pernambuco, municipality of Sertânia, quantify the soil protein related to easily extractable glomalin (SPREEG) and to total glomalin (SPRTG), experiments were conducted in a greenhouse. For this study 10 composite soil samples were collected, with points randomly defined. Samples were homogenized and analyzed for physical and chemical characteristics. Being used for immediate examination and preparation trap cultures (one three-month cycle of propagation) to AMF, using as host plants sorghum (Sorghum bicolor L. Moench), and peanut (Arachis hypogaea L.). To determine the MPN of infective propagules of AMF in Haplic Luvisols, soil inoculum samples were diluted in the proportions of 0, 1:10, 1:100 and 1:1000 (soil inoculum: diluent soil, v:v) with 5 repetitions each, using maize (Zea mays L.) as host plant. The direct count (DC) differed significantly from the indirect (IC) of AMF with averages of 961.3 and 517.4 glomerospores per 100g soil, respectively. The NMP of infective propagules of AMF propagules found was 23 cm-3 and SPREEG and SPRTG were approximately 0.46 and 0.26 mg glomalin g-1 aggregate, respectively.

The diversity and community structure of arbuscular mycorrhizal fungi (AMF) associated with coconut (Cocos nucifera) roots was evaluated by next generation sequencing (NGS) using partial sequences of the 18S rDNA gene and by spore isolation and morphological identification from rhizosphere soil. Root samples from six different Green Dwarf coconut plantations and from one organic plantation surrounded by tropical dry forest along the coastal sand dunes in Yucatan, Mexico, were collected during the rainy and dry seasons. In total, 14 root samples were sequenced with the Illumina MiSeq platform. Additionally, soil samples from the dry season were collected to identify AMF glomerospores. Based on a 95–97% similarity, a total of 36 virtual taxa (VT) belonging to nine genera were identified including one new genus-like clade. Glomus was the most abundant genus, both in number of VT and sequences. The comparison of dry and rainy season samples revealed differences in the richness and composition of AMF communities colonizing coconut roots. Our study shows that the main AMF genera associated with coconut tree roots in all samples were Glomus, Sclerocystis, Rhizophagus, Redeckera, and Diversispora. Based on glomerospore morphology, 22 morphospecies were recorded among which 14 were identified to species. Sclerocystis sinuosa, Sclerocystis rubiformis, Glomus microaggregatum, and Acaulospora scrobiculata were dominant in field rhizosphere samples. This is the first assessment of the composition of AMF communities colonizing coconut roots in rainy and dry seasons. It is of importance for selection of AMF species to investigate for their potential application in sustainable agriculture of coconut. [ABSTRACT FROM AUTHOR]

The main goal of this study was to determine the diversity and activity of arbuscular mycorrhizal fungi (AMF) in an area degraded by limestone mining within the semi-arid region of Brazil known as the caatinga (shrublands). Near a limestone quarry, we selected two areas of caatinga (preserved and degraded) for study. The number of glomerospores did not differ significantly between the two areas. There was a trend toward the most probable number of infective propagules being higher in the degraded area. Twenty AMF taxa were identified in the two sampled areas, species richness, diversity and evenness being higher in the preserved area. Two species of Racocetra represent new records for the semi-arid region of Brazil. Glomerospore production and AMF species richness were unaffected by mining activity in the study area.

ABSTRACT This study aimed to thoroughly investigate communities of arbuscular mycorrhizal fungi (AMF) in six coastal, mined, reconstituted and revegetated dune areas in Northeast Brazil. AMF spore density and species richness as well as the numbers of infective AMF propagules and glomalin-related soil protein (GRSP) were analyzed. Four areas had been restored for 16, 12, 8 and 4 years, and after being mined, reconstituted and re-vegetated, the fifth was mined and reconstituted but not yet re-vegetated, and the sixth had a native and undisturbed coastal forest vegetation. The soil samples were sampled in the dry and wet seasons of 2005. The number of infective propagules was significantly higher in the dry than in wet season, except in the un-vegetated dune area, which had less than 0·2 propagules cm−3 soil. AMF spore density and especially GRSP contents changed little between the seasons. GRSP contents were positively correlated to Al and Fe soil levels and were highest in the restinga forest. In total, 29 AMF species were identified, and glomoid and gigasporoid species predominated in all areas. AMF species richness and viable propagules of AMF were lowest in the un-vegetated dune area. Remarkably, higher species richness (28) was found in the re-vegetated areas, compared with the forest area that had only 10 species. The numbers of infective propagules tended to be also lower in the forest than in the re-vegetated sites. In conclusion, re-vegetation appears to favour the AMF communities in terms of infective propagule numbers and AMF species richness. Copyright © 2011 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]