Structure, dynamics, and ecological functions of rhizosphere fungal communities associated with maize (Zea mays L.) across contrasting rainfed agroecosystems

Résumé fourni par la source

Rhizosphere fungi play a critical role in maintaining soil health and enhancing crop productivity. However, knowledge of their diversity and population structure in maize fields across contrasting territories or agroecological zones (AEZs) remains limited, especially in Africa. This study aimed to characterize the diversity, composition, and distribution of fungal communities in the maize rhizosphere across three territories belonging three territories located in two distinct AEZs in South Kivu (Democratic Republic of the Congo). Maize Rhizosphere soils were collected from 19 sites across the territories (Kabare, Walungu and Uvira) and their associated fungal community was analysed by ITS sequencing using the Illumina MiSeq platform. Fungal richness varied significantly across territories and AEZs (lowland vs highland), with higher richness observed in Walungu (highland-). Fungal communities were dominated by Basidiomycota, accounting for 70.2% of the total relative abundance, followed by Ascomycota (13.4%), and Glomeromycota (7.25%). Together, they represented 90.85% of ASVs, although their distribution varied significantly among territories. Basidiomycota was relatively more abundant in Kabare and Walungu (highland), whereas Ascomycota and Glomeromycota were relatively more abundant in Uvira (lowland). Functional guild analysis indicated a predominance of putative saprotrophs, followed by putative symbiotrophs (including AMF and endophytes) and a smaller proportion of putative pathotrophs, with several guilds showing site-specific patterns. NMDS and RDA analyses showed that edaphic and microclimatic gradients strongly influenced fungal community structure. In Uvira, fungal abundance was positively associated with temperature, wind speed, soil organic matter, phosphorus, and CTI ( Compound Topographic Index ), but negatively correlated with slope and soil nitrogen. In Kabare, cation exchange capacity, potassium, soil moisture, and bulk density were the main drivers of fungal abundance. In Walungu, sodium content and landscape curvature positively shaped fungal communities, whereas soil organic matter negatively affected several taxa. Overall, these findings provide valuable insights into the environmental drivers of fungal communities in maize rhizospheres and may support future strategies to harness beneficial fungi for disease management and biofertilization in South Kivu.

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