Phenotypic and transcriptomic shifts in roots and leaves of rice under the joint stress from microplastic and arsenic

Abstract

Co-contamination of soil from microplastics (MP) and arsenic (As) is becoming more prevalent, posing a severe threat to agricultural productivity. However, how this joint pollution affects crop growth needs to be better understood. To assess this, we investigated the transcriptomic and phenotypic patterns of rice (Oryza sativa) to MP, As, and their mixtures. The results revealed that, compared to As, MP had much less impact on rice growth, while the MP-As mixture decreased rice’s aboveground biomass and altered As’s biodistribution in rice tissues. Transcriptome further corroborated this pattern: 13 (294), 4195 (1842), and 3112 (2063) genes differentially regulated in response to MP, As, and their mixtures were observed in root (leaf) tissues, respectively. The joint application of MP and As produced a synergistic effect on crucial metabolic processes, such as carbohydrate, carboxylic acid, oxoacid, organic acid, amino acid, and tetrapyrrole metabolism. Moreover, we found that the joint stress reprogrammed the expression of hub genes encoding photosynthetic enzymes, protein kinases, and transcription factors, which likely reflect a transcript-driven tradeoff strategy between rice growth and defense. Together, these results strongly indicate that MP aggravated the As-induced toxicity in rice plants, which may impact the crop’s acclimation to other abiotic field environments.