Responses of maize roots, rhizosphere enzyme kinetics and prokaryote diversity to alternating precipitation: insights from a three-year field study

• Background: Understanding how annual weather variation, including droughts, affects plant roots and rhizosphere prokaryote dynamics in different years is essential for predicting plant responses to climate fluctuations. This study aimed to investigate the effects of alternating dry and moist years on maize root gene expression and rhizosphere prokaryote composition, and to reveal interactions between the two. • Methods: Zea mays B73 wild-type (WT) and a root hair-deficient mutant (rth3) were grown on two substrates during a 3-year field experiment with alternating precipitation, designated as dry, moist and dry. Root gene expression was analysed between the two dry years and the moist year, supported by superoxide dismutase activity. The rhizosphere was analysed by measuring the enzyme kinetic parameters β-glucosidase, acid phosphatase, leucine aminopeptidase and N-acetylglucosaminidase, accompanied by the 16S rRNA-based and 1-aminocyclopropane-1-carboxylate deaminase (acdS + )-based microbial community. • Key Results: Year was the main driver of root gene expression and the 16S rRNA-based microbial community, with a distinct pattern of drought-responsive genes between dry years and the moist year. Substrate was the main driver of the acdS + -based microbial community and influenced root gene expression and the 16S rRNA-based microbial community, indicating interactive effects between maize roots and rhizosphere prokaryotes. The effect of year and substrate on enzyme kinetics was enzyme-specific. Root hair presence had a marginal effect. • Conclusions: This study highlights the role of annual weather variation in shaping root gene expression, rhizosphere prokaryotes and enzyme kinetics and underlines the role of substrate in structuring acdS + -based microbial communities. Our results suggest that plant–microbe interactions are highly sensitive to precipitation variability and might be influenced by repeated maize planting. They emphasize the importance of precipitation history in shaping plant–microbe ...