The effect of arbuscular mycorrhizal fungi on the growth of wheat seedlings with contrasting phosphorus use efficiencies under low phosphorus stress.

BACKGROUND

Arbuscular mycorrhizal fungi (AMF) can stimulate root development in plants and enhance their ability to adapt to stress conditions. This study investigated the effects of arbuscular mycorrhizal fungi (AMF) inoculation on the growth, hormone dynamics, and phosphorus (P) metabolism of two wheat cultivars with differing phosphorus utilization efficiencies under both normal and low phosphorus concentration conditions. The research focused on the symbiotic interaction between AMF and these wheat varieties to elucidate their responses to varying phosphorus availability.

RESULT

The experiment showed that phosphorus inefficient wheat SW14 inoculated with AMF for 30 days under low phosphorus stress showed significant enhancement in plant height, biomass, leaf width, stem thickness, root surface area, and vegetative phosphorus content, while total root length and primary root length were reduced, This change in root length was attributed to the fact that the root system undergoes elongation and growth to adapt to the adversity under low phosphorus stress in crops, and inoculation with AMF effectively alleviated the extent of this low phosphorus stress. while IAA, SL, cellulose and lignin hormone levels and APC enzyme activities were significantly elevated, and stem structure was significantly optimized; whereas, the phosphorus-efficient variety, SW2, did not show significant improvement due to its own unique tolerance to low phosphorus stress (Table 2). Transcriptomic profiling identified 2,500 differentially expressed genes (DEGs: 983↑/1,517↓), enriched in ABC transporters (ko02010), Plant hormone signal transduction (ko04075), and MAPK signaling pathway - plant (ko04016), Cutin, suberin and wax biosynthesis(ko00073). WGCNA further resolved that AMF responded to low phosphorus stress by up-regulating the expression of cellulose, lignin, APC synthesis, and IAA/SL-related genes in SW14, with the most relevant phenotypes shown to correlate to primary root length, total root length, root dry weight and stem diameter.

CONCLUSION

AMF inoculation significantly enhanced growth and dry matter accumulation in the low-phosphorus-use-efficiency wheat variety SW14 under phosphorus-deficient stress. This treatment concurrently stimulated IAA, SL, and APC activities, resulting in increased phosphorus uptake/accumulation, notable accumulation of cellulose and lignin, and consequently significantly improved stem strength. Although AMF inoculation improved growth in the high-phosphorus-use-efficiency wheat variety SW2, these enhancements failed to reach statistical significance.