Integrated transcriptome, small RNA and degradome sequencing approaches proffer insights into chlorogenic acid biosynthesis in leafy sweet potato

Abstract

Leafy sweet potato is rich in total phenolics (TP) which play key roles in health protection, the chlorogenic acid (CGA) constitutes the major components of phenolic compounds in leafy sweet potato. Unfortunately, the mechanism of CGA biosynthesis in leafy sweet potato is unclear. To dissect the mechanisms of CGA biosynthesis, we performed transcriptome, small RNA (sRNA) and degradome sequencing of one low-CGA content and one high-CGA content genotype at two stages. A total of 2,333 common differentially expressed genes (DEGs) were identified, and the enriched DEGs were related to photosynthesis, starch and sucrose metabolism and phenylpropanoid biosynthesis. The functional genes, such as CCR, CCoAOMT and HCT in the CGA biosynthetic pathway were down-regulated, indicating that the way to lignin was altered, and two possible CGA biosynthetic routes were hypothesized. A total of 38 DE miRNAs were identified, and 1,799 targets were predicated for 38 DE miRNAs by using in silico approaches. The target genes were enriched in lignin and phenylpropanoid catabolic processes. Transcription factors (TFs) such as apetala2/ethylene response factor (AP2/ERF) and Squamosa promoter binding protein-like (SPL) predicated in silico were validated by degradome sequencing. Association analysis of the DE miRNAs and transcriptome datasets identified that miR156 family negatively targeted AP2/ERF and SPL. Six mRNAs and six miRNAs were validated by qRT-PCR, and the results showed that the expression levels of the mRNAs and miRNAs were consistent with the sequencing data. This study established comprehensive functional genomic resources for the CGA biosynthesis, and provided insights into the molecular mechanisms involving in this process. The results also enabled the first perceptions of the regulatory roles of mRNAs and miRNAs, and offered candidate genes for leafy sweet potato improvements.

Genotypic variations in GST genes reveal a regulatory role in the accumulation of caffeoylquinic acids in leafy sweet potato

“…Moreover, plants from the EC16 variety accumulated more CQAs compared to the FS7-6 variety (Fig. 1B), which is in agreement with the ndings of Liu et al, (Liu et al 2021). It could be assumed that the differences in CQAs contents between varieties are due to the genetic heritage of each variety, which probably in uences their ability to resist various environmental stresses that stimulate the enzymatic genes involved in the PPs pathway responsible for CQAs biosynthesis.…”

“…The CQAs were quanti ed using the method described by Liu et al (Liu et al 2021) with few modi cations. Brie y, 50 mg of each sample was dissolved in 70% ethanol (v/v) followed by water bath (60°C, 1h) and then centrifugation (12000 rpm, 10 min).…”

“…In China, its tuberous roots have long been considered the only edible parts of the plant, however, more recently the leaves and tender stems of leafy sweet potato are increasingly consumed as fresh vegetables, making the production of these new cultivars with improved foliar bioforti cation pro table for farmers (Tang et al 2021). Leafy sweet potato is rich in vitamins, proteins, carotenoids, avonoids, anthocyanins and caffeoylquinic acids (CQAs) (Suárez et al 2020;Liu et al 2021). The CQAs, including monoCQAs (1-CQA, 3-CQA, 4-CQA, 5-CQA) and diCQAs (1,3-diCQA, 1,4-diCQA, 1,5-diCQA, 3,4-diCQA, 3,5-diCQA, 4,5-diCQA) possess antioxidant properties, which are important for the treatment of chronic human diseases and the resistance of plants to environmental adversaries (Naveed et al 2018; Cheevarungnapakul et al 2019).…”

Unprecedented organelle genomic variations in morning glories reveal independent evolutionary scenarios of parasitic plants and the diversification of plant mitochondrial complexes

“…Transcriptomes enriched with oligo-dT would introduce bias since organelle transcripts do not generally contain a polyA tail [ 97 ]. Based on that, sweet potato rRNA-depletion transcriptome data (SRA: SRR10538086 [ 98 ]) were employed and were mapped to the mitogenome to check the expression.…”

Comparative Transcriptomic Analyses of Chlorogenic Acid Biosynthesis Pathways in Diploid and Triploid Camellia sinensis

“…Therefore, a triploid tea plant and a diploid tea plant were selected as experimental materials in present experiment to study the key genes of CGA biosynthesis in Camellia sinensis. Liu et al (2021) utilized one low-CGA content and one high-CGA content in sweet potato to dissect the mechanisms of CGA biosynthesis by transcriptome data, and found that expression of HCT and other genes were significantly different in the two phenotypes, and therefore inferred that those genes may be the key gene that controlled the synthesis of sweet potato CGA (Liu et al 2021). Wang et al (2020) used the transcriptome to study the CGA biosynthesis of diploid and tetraploid Lonicera japonica, they found that changes in the expression level of some key genes in the biosynthesis pathway at different growth stages led to changes in the content of CGA (Wang et al 2020).…”