Abstract：
The effects of co-exposure to antibiotics and microplastics in agricultural systems are still unclear. This study investigated the effects of florfenicol (FF) and polystyrene microplastics (PS-MPs) on photosynthetic carbon assimilation in rice seedlings. Both FF and PS-MPs inhibited photosynthesis, while PS-MPs can alleviate the toxicity of FF. Chlorophyll synthesis genes (HEMA, HEMG, CHLD, CHLG, CHLM, and CAO) were down-regulated, whereas electron transport chain genes (PGR5, PGRL1A, PGRL1B, petH, and ndhH) were up-regulated. FF inhibited linear electron transfer (LET) and activated cyclic electron transfer (CET), which was consistent with the results of the chlorophyll fluorescence parameters. The photosynthetic carbon assimilation pathway was altered, the C3 pathway enzyme Ribulose1,5-bisphosphatecarboxylase/oxygenase (RuBisCO) was affected, C4 enzyme ((phosphoenolpyruvate carboxykinase (PEPCK), pyruvate orthophosphate dikinase (PPDK), malate dehydrogenase (MDH), and phosphoenolpyruvate carboxylase (PEPC))) and related genes were significantly up-regulated, suggesting that the C3 pathway is converted to C4 pathway for self-protection. The key enzymes involved in photorespiration, glycolate oxidase (GO) and catalase (CAT), responded positively, photosynthetic phosphorylation was inhibited, and ATP content and H+-ATPase activity were suppressed, nutrient content (K, P, N, Ca, Mg, Fe, Cu, Zn, Mn, and Ni) significantly affected. Transcriptomic analysis showed that FF and PS-MPs severely affected the photosynthetic capacity of rice seedlings, including photosystem I, photosystem II, non-photochemical quenching coefficients, and photosynthetic electron transport.
摘要：
农业系统中共同接触抗生素和微塑料的影响尚不清楚。本研究研究了氟苯尼考（FF）和聚苯乙烯微塑料（PS-MPs）对水稻幼苗光合碳同化的影响。FF和PS-MPs都抑制光合作用，而PS-MPs可以减轻FF的毒性。叶绿素合成基因(HEMA，HEMG,CHLD,CHLG,CHLM,和CAO)被下调，而电子传递链基因(PGR5，PGRL1A，PGRL1B,petH,和ndhH)上调。FF抑制线性电子转移（LET）和激活循环电子转移（CET），结果与叶绿素荧光参数一致。光合碳同化途径发生了改变，C3途径酶Ribulose1,5-二磷酸羧化酶/加氧酶（RuBisCO）受到影响，C4酶（（磷酸烯醇丙酮酸羧激酶（PEPCK），丙酮酸正磷酸二激酶（PPDK），苹果酸脱氢酶（MDH），和磷酸烯醇丙酮酸羧化酶（PEPC））和相关基因显着上调，表明C3途径转化为C4途径进行自我保护。参与光呼吸的关键酶，乙醇酸氧化酶（GO）和过氧化氢酶（CAT），积极回应,光合磷酸化被抑制，ATP含量和H+-ATP酶活性被抑制，营养成分（K，P,N,Ca,Mg,Fe,Cu,Zn,Mn,和Ni)显著影响。转录组分析表明,FF和PS-MPs严重影响水稻幼苗的光合能力,包括光系统I,光系统II，非光化学猝灭系数，和光合电子传递。
