R CO2 enrichment. Comparing the RPKM (Reads Per Kilobase of transcript per Million fragments mapped) values of all genes in carotenoid metabolism, the values of most genes inside the degradation procedure had been smaller than these inside the synthesis approach, which indicates that the synthesis of carotenoids was dominant within this study. The enhance in carotenoid content under CO2 enrichment could be due to the gradual reduce in carotenoid degradation and also the considerable enhancement on the synthesis reaction. NECDs will be the rate-limiting enzymes that manage the conversion of carotenoids to ABA, and they are substantially upregulated during ageing34. Within this study, NCED-3 was drastically downregulated, which may possibly be associated with the leaf position we chosen for sampling. CYP707 can be a essential enzyme for ABA decomposition and metabolism23 and is encoded by eight genes: CYP707a-2 was significantly upregulated, CYP707b-1 was substantially downregulated, along with the expression of four genes was downregulated, indicating that CYP707 directly inhibited ABA degradation, thereby minimizing the degradation of carotenoids.The effect of CO2 enrichment on BCH activity. Analysis showed that (BCH) was an enrichment enzyme inside the KEGG HDAC10 manufacturer pathway of carotenoid synthesis and was also a important rate-limiting enzyme inside the carotenoid biosynthetic metabolic pathway. Below CO2 enrichment circumstances, enzyme activity was normally drastically larger than that on the handle, and activity progressively elevated as remedy progressed. The enzyme activity of plants in the control and also the therapy peaked at 61 days after which gradually decreased (Fig. 5). Reverse transcription quantitative real-time PCR verification. Ten DEGs (gene14276, gene15015, gene4178, gene1181, gene24757, gene946, Cathepsin K web gene33346, gene33340, gene2438, and gene13390) were selected for RT-qPCR verification in plants below CO2 enrichment and manage conditions to verify the reliability with the RNA-Seq. results (Fig. six). Comparing the RT-qPCR outcomes with the sequencing benefits, the expression trend inside the 10 genes beneath CO2 enrichment was consistent with that with the sequencing final results, indicating the reliability with the sequencing approach. Amongst them, gene14276 and gene4178 had been drastically upregulated, gene15015 and gene1181 have been significantly downregulated inside the carotenoid metabolic pathway (Fig. 6), along with the expression trend of those four genes corresponded for the sequencing benefits.Pigment content is definitely the basis of carbon and nitrogen metabolism in plants and plays a constructive role in promoting crop development and development, yield, and quality35. Within this study, the total biological yield improved following CO2 enrichment. In addition, in the initial stage following CO2 enrichment, aboveground biological yield elevated faster than belowground yield. In the similar time, the contents of carotenoids in leaves and roots improved, andDiscussionScientific Reports |(2021) 11:12073 |https://doi.org/10.1038/s41598-021-91522-7 Vol.:(0123456789)www.nature.com/scientificreports/RPKM Enzyme ID Enzyme nine- cis- epoxycarotenoid dioxygenase (NCED) Coded gene in carrot gene15015/NCED-3 gene17667/NCED-2 gene1842/NCED-5 gene19824/NCED-1 gene22296/NCED-9 gene28051/NCED-8 gene31667/NCED4-CCD4 gene3531/NCED-6 gene4514/NCED-7 1.two.3.14 Xanthoxin dehydrogenase (ABA2) abscisic aldehyde oxidase (AAO3) DCAR_005308 DCAR_022906 DCAR_022905 DCAR_031841 abscisic acid 8′-hydroxylase (CYP707A) gene216/CYP707a-1 gene4178/CYP707.