Effects of arbuscular mycorrhizal fungi on sugarcane growth and nutrient- related gene co-expression network under different fertilization levels

: Sugarcane is one of the important sugar crops in China. Arbuscular mycorrhizas (AM) fungi are widely distributed. Researches have shown that AM fungi infecting plant roots can promote nutrient absorption and growth of plants. In this study, pot experiment was used to set up with two fertilization levels of conventional fertilization (N) and reduced fertilization (R), and inoculated (AM) and control (CK). There were four treatments in total, and four replicates were set in each treatment. The results revealed that the plants inoculated with AM fungi did not only significantly increased the biomass accumulation, but also significantly affected the pH value, alkali hydrolyzable nitrogen and available phosphorus of sugarcane rhizosphere soil. The biomass accumulation in the AM fungus inoculation treatment under reduced fertilization was significantly higher than that of conventional fertilization. The turquoise module and darkgreen module with high specificity with nutrient phenotypes such as nitrogen and phosphorus were screened by weighted gene co-expression network analysis (WGCNA). The core genes of the module were screened with KME value greater than 0.7 as the threshold, and 408 and 21 core genes were screened, respectively. GO enrichment indicated that these core genes were mainly involved in nutrient transport, metabolism, and enzyme catalysis pathways. Based on annotation information and the connectivity of genes, 28 core genes related to the absorption and transportation of nutrients such as nitrogen and phosphorus and 108 related candidate genes were detected among the core genes screened. This study reveals the effects of AM fungi on sugarcane nutrient absorption, and provides a theoretical basis for further understanding of the molecular mechanisms of AM fungi affecting sugarcane nutrient absorption.