Adaptability of plants to phosphorus deficiency shapes bacterial community and spatial patterns of enzyme activities in rhizosphere

Abstract

Phosphorus (P) availability influences the spatial distribution of carbon (C)-cycling enzyme activities in the rhizosphere through its effects on plant growth and microbial activity. However, the influence of P availability on the spatial patterns of C and P hydrolase activities remains unclear in the rhizosphere of Maize (Zea mays L.) and narrow-leaf lupine (Lupinus angustifolius L.), which exhibit contrasting P deficiency adaptation and acquisition strategies. This study analyzed the spatial patterns of C and P hydrolase activities through zymography and correlated them with bacterial community structure in maize and lupine rhizospheres. Under P-deficient conditions, maize exhibited severe growth restriction while demonstrating a 2.2–9.6-fold increase in root exudation compared to P-sufficient conditions. The enhanced exudation under P deficiency promoted r-strategist bacterial proliferation (e.g., Ktedonobacteria and Xanthomonadales) while reducing K-strategist abundance (Actinobacteriota, Chloroflexia, and Alphaproteobacteria). Maize rhizosphere enzyme activities and hotspot areas demonstrated positive correlation with K-strategist abundance and negative correlation with r-strategist abundance. P-sufficient maize exhibited 15–550% higher C- and P-cycle-related enzyme activity and hotspot areas, attributed to its enhanced root system and predominance of K-strategists with superior enzyme synthesis capabilities. Lupine demonstrated superior P deficiency adaptation, producing 2–19 times more DOC and organic acids than maize. Consequently, lupine showed no significant alterations in enzyme activity, hotspot areas, or bacterial community composition in response to P availability. These findings demonstrate that plant-specific P deficiency adaptation mechanisms distinctly influence the spatial distribution of C-cycling enzyme activity and bacterial community structure in the rhizosphere.