Synergistic impacts of bisphenol A and elevated temperatures on Oryza sativa development and rhizosphere microbiome in diverse cultivars

Bisphenol A (BPA) has emerged as a significant environmental pollutant, posing serious risks to ecosystems, especially in agricultural settings. It is essential to evaluate the toxic effects of BPA on rice cultivation and soil microbiome amid rising global temperature. Therefore, this study investigated the simultaneous effects of BPA (0, 1.5, 12, and 20 mg kg^-1) along with two temperature regimes (29/24⁰C and 42/38⁰C) on the growth, development, and rhizospheric microbial dynamics of two contrasting rice genotypes: High-Temperature Resistant (HTR-1) and High-Temperature Sensitive (HTS-5). The results showed that elevated BPA concentrations under rising temperatures significantly inhibited chlorophyll content (by 54.70 % and 42.40 %), reduced ROS scavenging activity, modulated abscisic acid production (by 84.89 % and 53.00 %), leading to impaired physiological responses in exposed rice genotypes. Furthermore, HTR-1 exhibited higher ABA levels, a lower transpiration rate, and reduced BPA accumulation in seedlings under stress conditions, resulting in superior growth compared to HTS-5. The combined stress dramatically altered the structure and composition of bacterial and fungal communities and favoured the dominance of more resilient phyla and genera. Notably, bacterial phyla such as Proteobacteria (16.50 %) and Chloroflexi (26.60 %), as well as fungal phyla Ascomycota (24 %) and Chytridiomycota (210 %) were abundant, while, Anaerolinea and Zopfiella were notably enriched at the genus level in the rhizosphere of HTR-1 genotype. This study demonstrated that selecting temperature-tolerant rice varieties and understanding plant-microbe interactions are crucial for mitigating the combined effects of heat and BPA pollution in sustainable agriculture.