Arbuscular Mycorrhizal Fungi - Methods and Protocols

Arbuscular mycorrhizal (AM) fungi are soil inhabitants that form the most ancient and widespread symbiosis with plants, including major crops. They all belong to the subphylum 54 Glomeromycotina of the Mucoromycota. The emergence of AM fungi and land plants 55 coincided at nearly 450 million years ago, suggesting that these fungi probably facilitated 56 land plant colonization. AM fungi are complex but extremely successful organisms. Since 57 their appearance, they have accompanied plants through evolution and persisted along 58 periods of important environmental change to become ecologically and agronomically 59 important symbionts that improve fitness of most extant plant taxa across the globe. 60 Nutrient acquisition appears to be the dominant role of AM fungi, as they provide access 61 to low soil mobility mineral nutrients, mainly phosphorus, through the large network of 62 extraradical mycelium they develop in the soil. Additional benefits arise from the symbiosis, 63 including higher tolerance to biotic and abiotic stresses and major contributions to relevant 64 ecosystem functions such as soil aggregation and reduced nutrient loss. AMfungi represent, 65 therefore, a very promising tool for agroecology to reduce the amount of fertilizers and 66 pesticides required for food production. AM fungi have some singular biological traits, which have to some extent limited 68 experimental approaches for the study of their complexity and for their successful exploita- 69 tion in agriculture. One peculiarity is that they are obligate biotrophs that depend on living 70 root tissue for carbon supply, either in the form of carbohydrates or lipids, to complete their 71 life cycle. Another peculiarity is that they develop a coenocytic mycelial network and large 72 asexual spores having multiple nuclei. Each nucleus within a coenocytic hypha or spore 73 contains different polymorphic DNA sequence variants, and hyphae of different isolates of 74 the same species can anastomose and exchange genetic material. Although no sexual 75 reproduction has been described so far, they possess genetic information essential for sexual 76 reproduction processes, including meiosis and recombination. These distinctive features 77 have made it difficult to define the concepts of species and individual in this group of fungi 78 and have limited the possibility of applying standard methodologies for their study. 79 The aim of this book is to compile the most comprehensive and up-to-date collection of 80 cutting-edge protocols used in AM fungal research. It is a practical and experience-based 81 book that includes methods for isolation, cultivation, detection, and quantification of AM 82 fungi, the use of metagenomics for community studies, and experimental procedures for 83 functional genomics. This book will hopefully help researchers—from newcomers to expe- 84 rienced—to perform experiments that fill the gaps in our knowledge of the basic biology, 85 functions, and ecology of AMfungi. This basic understanding willmake it possible to deploy 86 these plant fungal symbionts in agriculture more effectively, which, in turn, will have a 87 considerable economic, social, and environmental relevance. 88 Finally, we would like to thank all authors for their commitment and contribution to 89 this book.