Microplastics affect the quality of Cucumis melo. L by regulating the jasmonic acid signaling pathway

Microplastics (MPs) are pervasive in agricultural soils, yet their mechanistic impacts on fruit quality under protected agriculture remain unclear. Here we compared polyethylene (PE) and polybutylene adipate-co-terephthalate (PBAT) MPs in a melon system and established a microplastic-plant hormone-fruit quality regulatory chain integrating rhizosphere processes and jasmonic acid (JA) signaling. PE-MPs significantly impaired fruit quality, reducing the sugar-acid ratio by up to 43.9 % through disruption of Sphaerobacter thermophilus-mediated metabolite synthesis and suppression of jasmonic acid (JA) signaling. In contrast, PBAT-MPs exerted no direct effect on fruit quality but altered rhizosphere composition, increasing organic matter, lowering nitrogen availability, and suppressing key carbon- and nitrogen-cycling microbes, while enriching MP-degrading populations that indirectly modulated the JA pathway. At the molecular level, both PE- and PBAT-MPs downregulated JA biosynthetic genes and inhibited 12-oxophytodienoate reductase activity, with stronger inhibition by PE-MPs (-22.61 %) than PBAT-MPs (-7.39 %). Collectively, these findings reveal distinct pathways through which MPs influence crop quality, providing mechanistic insights for mitigating MP-induced risks in facility agriculture.