Communities of arbuscular mycorrhizal fungi in two endemic species of the campo rupestre ecosystem

Abstract

The present work aimed to investigate and quantify the diversity of arbuscular mycorrhizal fungi (AMF) found in the soil adjacent to the roots of Vellozia ramosissima and Eremanthus incanus in two ferruginous campo rupestre environments (FCR) and two quartzitic campo rupestre environments (QCR) of Serra do Espinhaço, Brazil. Spore density of AMF in the soil, quantity of glomalin-related soil protein (GRSP), and degree of root colonization by AMF were analyzed. Eremanthus incanus exhibited 24 species of arbuscular mycorrhizal fungi (AMF) in its rhizosphere, with four being exclusive to quartzitic rupestrian fields (QCR) and six to ferruginous rupestrian fields (FCR). Vellozia ramosissima had 20 AMF, with five exclusive to QCR and one to FCR. The high richness of AMF associated with the rhizosphere of the two studied species may be the determining factor for the successful establishment of these plants in environments under adverse edaphoclimatic conditions and low productivity. The genera Acaulospora, Glomus, and Scutellospora were distributed among all the studied areas and had the greatest species richness. Species richness of AMF tended to be higher in environments with higher floristic richness, although these areas had lower spore density. There was a greater quantity of GRSP in the ferruginous environments while root colonization by AMF was higher for E. incanus than V. ramosissima. Principal component analysis of chemical attributes of the soil revealed two groups influenced by lithology (ferruginous vs. quartzitic). Indicator species analysis revealed the prevalence of five indicator species in the studied environments; two of the species were specific to QCR1, one to FCR1, and two to FCR2. Contrary to expectations, sites with lower species richness of AMF had higher values for the Shannon diversity index (H′), because the sampled spores in these environments were distributed more uniformly among the registered AMF species.