Investigation Of Arbuscular Mycorrhizal Fungi In The Roots Of21Wheat Cultivars

Arbuscular mycorrhizal (AM) fungi, a type of renowned plant-associated microbes, can form mutualistic symbiosis with the roots of most crops. AM fungi can efficiently promote plant uptake for phosphorus and nitrogen, reduce the damage of root pathogens and protect plants against several types of stress, and, consequently, the potentials of AM fungi in agricultural practices have been widely appreciated. Breeding new cultivars with high AM dependency is a promising technique for future sustainable agriculture, but this technique is developing slowly since we have not fully understood the structural and functional differences of AM fungal communities among crop cultivars. To elucidate the relationships between cultivars and AM fungi, we performed a field experiment in the Loess Plateau of China, in which21winter wheat cultivars were planted at a same field, and the root AM colonization, extraradical hyphal biomass, spore community, AM fungal community colonizing roots and some agronomic parameters were measured. The main results are listed below.(1). All studied wheat cultivars were colonized by AM fungi. The mean of percent root of AM colonizaiton was31.8%, vesicular colonization was1.1%, arbuscular colonization was2.6%, extraradical hypal length density was7.73m g-1dry soil and the spore density was49spores per20g dry soil. Surprisingly, all AM fungal variables described above were similar among21cultivars. AM colonization and vesicular colonization were correlated negatively with soil available phosphorus, and the spore density showed positive correlations with both soil organic carbon and available nitrogen; these results suggest that the variations of soil characteristics would influence the colonization and sporulation of AM fungi.(2). Eleven AM fungal spore morphotypes were isolated from rhizosphere soils of all wheat cultivars, and the richness of spore morphotypes were similar among21cultivars. The spore communities were highly correlated with soil pH, available nitrogen and organic carbon, whereas none of wheat variables were correlated significantly with the spore communities.(3). Sixteen AM fungal phylotypes were detected from63root samples. ZYW-Glo10was the most dominant phylotype (48%abundance, related to Funneliformis geosporum), followed by ZYW-GIo6(17%abundance, related to Rhizophagus intraradices), and these two dominant phylotypes were detected from roots of all cultivars, with an exception of no ZYW-G1o6in one cultivar. The richness of AM fungal phylotypes were much similar among19out of21cultivars, and it showed no significant correlations with all wheat and soil variables except the soil available phosphorus and soil total nitrogen. The communities of AM fungal phylotypes, however, were highly correlated with cultivar, wheat height, degree of drought resistance and the soil total nitrogen, suggesting the AM fungal communities colonizing roots were co-determined by the cultivar and soil characteristics.(4). In summary, the present study showed that the AM colonization, extraradical hyphal length density, spore density and some other AM fungal variables were much similar among21winter wheat cultivars, but the AM fungal communities colonizing roots varied among different cultivars. Future studies need to address whether the functions of AM fungal communities vary among different wheat cultivars, and also need to select a suitable combination of cultivar and AM fungal partners.