Composition of the root mycorrhizal community associated with Coffea arabica in Fifa Mountains (Jazan region, Saudi Arabia).

Arbuscular mycorrhizal fungi (AMF) constitute a key functional group of soil biota that can greatly contribute to crop productivity and ecosystem sustainability. They improve nutrient uptake and enhance the ability of plants to cope with abiotic stresses. The presence of AMF in coffee (Coffea arabica L.) plant roots have been reported in several locations but not in Saudi Arabia despite the fact that coffee has been in cultivation here since ancient times. The objective of the present study was to investigate the diversity of AMF communities colonizing the roots of coffee trees growing in two sites of Fifa Mountains (south-west Saudi Arabia): site 1 at 700 m altitude and site 2 at 1400 m. The AMF large subunit rDNA regions (LSU) were subjected to nested PCR, cloning, sequencing, and phylogenetic analysis. Microscopic observations indicated higher mycorrhizal intensity (24.3%) and spore density (256 spores/100 g of soil) in site 2 (higher altitude). Phylogenetic analysis revealed 10 phylotypes, six belonging to the family Glomeraceae, two to Claroideoglomercea, one to Acaulosporaceae and one to Gigasporaceae family. Glomus was the dominant genus at both sites and the genus Gigaspora was detected only at site 2. This is the first study reporting the presence of AMF in coffee roots and the composition of this particular mycorrhizal community in Saudi Arabia.

Mahdhi M ，Tounekti T ，Al-Turki TA ，Khemira H ... -  《-》

Diversity of arbuscular mycorrhizal fungi associated with acacia trees in southwestern Saudi Arabia.

Acacia species produce extensive, deep root systems with a capacity to develop mycorrhizal symbioses that facilitate plant nutrition via enhanced soil nutrient absorption. This study aimed to evaluate the mycorrhizal status and the diversity of arbuscular mycorrhizal fungi (AMF) associated with acacia trees in southwestern Saudi Arabia. The mycorrhizal status varied greatly between species. The highest values of AMF root colonization and spore density were observed in the roots and in the rhizospheric soil of Acacia negrii. DNA was extracted from plant roots and the AMF large subunit ribosomal DNA (LSU rDNA) was amplified by a nested polymerase chain reaction. A total of 274 LSU rDNA cloned fragments from roots of the three acacia trees were sequenced. Phylogenetic analysis revealed a high AMF diversity, especially in Acacia tortilis. On the basis of LSU rDNA sequences, AMF was grouped into five genera: Glomus, Claroideoglomus, Acaulospora, Gigaspora, and Scutellospora. The genus Glomus fungi were the dominant colonizers of all three acacia species, while the genus Scutellospora fungi were found only in A. tortilis roots. The high AMF-acacia diversity suggests that AMF plays an important role in the sustainability of acacia species in the arid environment.

Mahdhi M ，Tounekti T ，Abada E ，Al-Faifi Z ，Khemira H ... -  《-》

The diversity of arbuscular mycorrhizal fungi amplified from grapevine roots (Vitis vinifera L.) in Oregon vineyards is seasonally stable and influenced by soil and vine age.

Schreiner RP ，Mihara KL 《MYCOLOGIA》

Arbuscular Mycorrhizal Fungal Communities in the Roots of Maize Lines Contrasting for Al Tolerance Grown in Limed and Non-Limed Brazilian Oxisoil.

Gomes EA ，Oliveira CA ，Lana UG ，Noda RW ，Marriel IE ，de Souza FA ... -  《-》

Diverse communities of arbuscular mycorrhizal fungi inhabit sites with very high altitude in Tibet Plateau.

Diversity of arbuscular mycorrhizal fungi (AMF) is well studied in many ecosystems, but little is known about AMF in cold-dominated regions with very high altitude. Here, we examined AMF communities associated with two plant species in the Tibet Plateau. Roots and rhizosphere soils of Dracocephalum heterophyllum (pioneer species) and Astragalus polycladus (late-successional species) were sampled at five sites with altitude from 4500 to 4800 m a.s.l. A total of 21 AMF phylotypes were identified from roots and spores following cloning and sequencing of 18S rRNA gene, including eight new phylotypes and one new family-like clade. More AMF phylotypes colonized root samples of D. heterophyllum (5.4±0.49) than of A. polycladus (1.93±0.25). Vegetation coverage was the most important factor influencing AMF community composition in roots. Globally infrequent phylotype Glo-B2 in Glomus group B was the most dominant in roots, followed by globally frequent phylotype Glo-A2 related to Glomus fasciculatum/intraradices group. Our findings suggest that a diverse AMF flora is present in the Tibet Plateau, comprising both potentially habitat-selective and generalist fungi.

Liu Y ，He J ，Shi G ，An L ，Öpik M ，Feng H ... -  《-》