Overexpression of amiR2937 and amiR854e in Transgenic Arabidopsis thaliana Indirectly Impacts the Photosynthesis Performances by Targeting Specific Target Transcripts in the MEP Pathway

Abstract

Artificial miRNAs (amiRNAs) are artificial small RNAs engineered to silence specific plant mRNA transcripts. They are generated by expressing a functional microRNA (miRNA) with modified sequences in planta. Two miRNAs, miR2937 and miR854e, were selected based on their predicted target transcript, GGPS2 (geranylgeranyl pyrophosphate synthase 2) and TPS13 (terpenoid synthase 13). In the methylerythritol phosphate pathways, GGPS2 and TPS13 enzymes play a role in synthesizing sesquiterpenes, triterpenes, diterpenoids, carotenoids, gibberellins, and chlorophyll, respectively. Therefore, in this study, these two miRNAs were overexpressed in Arabidopsis thaliana in single and co-overexpression to analyze the change in the abundance of phytol and trans-beta-lone compounds. Through real-time quantitative polymerase chain reaction (RT-qPCR) analysis, a fold-up regulation of amiR2937 and amiR854e was observed in both transgenic plants harboring single and double constructs. Meanwhile, the GGPS2 and TPS13 enzymes showed a decreasing pattern in all transgenic plants, indicating that the miRNAs had successfully suppressed the target transcripts. Solid-phase microextraction-gas chromatography-mass spectrometry analysis revealed that the number of phytols was decreased in all transgenic plants but was significant in plants harboring construct miR854e. Meanwhile, there is an increasing pattern of trans-beta-ionone in all transgenic plants compared to wild-type plants. Consistently, with the decrease in phytol content, soil plant analysis development value, and total chlorophyll content, the photosynthesis rate decreased in the transgenic plants compared to the wild type. Indeed, the overexpression of these two miRNAs affects the production of target transcript and changes the plant development.