Growing season stage determines the stability of root symbiotic and pathogenic fungi associated with Pinus sylvestris var. mongolica in a semi-arid desert

The stability of symbiotic and pathogenic (Sy-Pa) fungal communities in roots is closely related to plant growth and health, especially in a desert ecosystem. Knowledge on stability of symbiotic and pathogenic fungi will improve advantageous interactions and forest ecosystem stability. The stability of Sy-Pa fungi is influenced by biotic and abiotic interactions among species. Previous studies have suggested that growing season stage and stand age are the two main factors of biotic factors. Nonetheless, we know little about the effect of growing season stage, stand age and abiotic factors on the stability of symbiotic and pathogenic fungi communities in roots. Therefore, we sampled roots of Pinus sylvestris var. mongolica in the different growing season stages: the rising stage of growing season (May), the peak of the growing season (July), and the end stage of growing season (September) across different stand ages: half-mature (27 years), nearly mature (33 years), and mature (44 years) in the Mu Us Desert, to explore the variations in the stability of Sy-Pa fungi communities. The results indicated that (1) The natural connectivity values among stand ages were mostly lower than those among the growing season stages. Co-occurrence networks of Sy-Pa fungi communities had more stable structures in the peak of the growing season and half-mature forests. (2) Mortierella and Geopora were the core keystone taxa in the networks of the different growing season stages and stand ages, respectively. Most of the core keystone taxa were symbiotic fungi. (3) Climate factors contributed more to Sy-Pa fungi networked communities than soil factors. The vari-ations of soil factors in different growing season stages were more significant than that in different stand ages. Our results showed the effect of growing season stage on the stability of Sy-Pa fungi communities was stronger than that of stand age, and climate factors were major driver of the stability of Sy-Pa fungi communities among different growing season stages and stand ages. We provide a new insight into the variation of co-occurrence patterns and community stability of Sy-Pa fungal communities in desert ecosystems.