Purple-fleshed sweet potato is good for health due to rich anthocyanins in tubers. Although the anthocyanin biosynthetic pathway is well understood in up-ground organs of plants, the knowledge on anthocyanin biosynthesis in underground tubers is limited. In the present study, we isolated and functionally characterized a root-preferential gene encoding dihydrokaempferol reductase (IbDHKR) from purple-fleshed sweet potato. IbDHKR showed highly similarity with the reported dihydroflavonol reductases in other plant species at the sequence levels and the NADPH-binding motif and the substrate-binding domain were also found in IbDHKR. The tissue profile showed that IbDHKR was expressed in all the tested organs, but with much higher level in tuber roots. The expression level of IbDHKR was consistent with the anthocyanin content in sweet potato organs, suggesting that tuber roots were the main organs to synthesize anthocyanins. The recombinant 44 kD IbDHKR was purified and fed by three different dihydroflavonol substrates including dihydrokaempferol (DHK), dihydroquerctin (DHQ) and dihydromyrecetin (DHM). The substrate feeding assay indicated that only DHK could be accepted as substrate by IbDHKR, which was reduced to leucopelargonidin confirmed by LC-MS. Finally, IbDHKR was overexpressed in transgenic tobacco. The IbDHKR-overexpression tobacco corolla was more highly pigmented and contained higher level of anthocyanins than the wild-type tobacco corolla. In summary, IbDHKR was a root-preferential gene involved in anthocyanin biosynthesis and its encoding protein, specifically catalyzing DHK reduction to yield leucopelargonidin, was a candidate gene for engineering anthocyanin biosynthetic pathway.
Anthocyanidin synthase (ANS) catalyzes the biosynthesis of anthocyanidin, which is a late gene for anthocyanin biosynthesis. In order to investigate the role of anthocyanidin synthase in anthocyanin biosynthesis, we cloned and characterized the anthocyanidin synthase gene from purple-flesh sweet potato (Ipomoea batatas (L.) Lam) Yuzi 263, which was designated as IbANS. The cDNA fragment of the ANS gene of sweet potato was 1375-bp in length which contained a 1086-bp open reading frame that encoded a 362-amino acid polypeptide. Comparative analysis showed that IbANS had a high similarity to other plant ANSs. The tissue expression profiles of IbANS indicated that it could be expressed in all tissues but at different levels. The higher expression level of IbANS was found in diameter (3.0 cm) of tuberous roots and periderms, while the lower expression level of IbANS was found in other tissues just coinciding with the anthocyanin content distribution.
Catharanthus roseus exhibits vibrant petals and displays robust resistance to disease and drought, making it highly valuable for ornamental and gardening applications. While the application of C. roseus as a source of anticancer drugs has gained considerable attention in recent years, there has been limited investigation into the regulatory mechanism underlying anthocyanin accumulation in the petals of C. roseus. This study comprehensively analyzed the metabolome and transcriptome of three distinct C. roseus varieties exhibiting different petal colors. Out of the 39 identified flavonoids, 10 anthocyanins exhibited significant variations in accumulation, directly contributing to the diverse coloration of C. roseus petals. Among them, malvidin 3-O-glucoside and petunidin 3-O-glucoside were identified as primary contributors to the purple petal phenotype, while peonidin 3-O-glucoside and delphinidin 3-O-glucoside exhibited the highest contribution rates to the red petals. Additionally, the variation content of cyanidin 3-O-rutinoside, delphinidin 3-O-glucoside, and petunidin 3-O-rutinoside also influenced the color transformation of C. roseus petals. RNA sequencing identified a total of 4173 differentially expressed genes (DEGs), including 1003 overlapping DEGs. A combined transcriptome and metabolome analysis showed that the coordinately regulated anthocyanin biosynthetic genes including chalcone isomerase (CHS), flavonoid 3′-hydroxylase (F3′H), and dihydroflavonol 4-reductase (DFR) played critical roles in the formation of the anthocyanins. MYB and bHLH transcription factors were also found to be significantly correlated with differences in flower color. These results serve as a foundation for future investigations into anthocyanin biosynthesis and regulatory mechanisms in C. roseus.
To study the variations of flavonoids contents in vine tips of sweetpotato (Ipomoea batatas) among different varieties, parts and the time of topping.The flavonoid contents in leaf, petiole and stem of vine tips at 6 different topping time of 3 varieties for vegetable-use Pushu 53, Guangcaishu No. 2 and Fushu 7-6, which were collected from Chongqing were determined by UV spectrophotometry with rutin as a standard substance.The results showed that the flavonoid content of Guangcaishu No. 2 was higher than that of Pusu 53, so was that of Pusu 53 than that of Fushu 7-6. The average flavonoid contents in leaf of 3 varieties were between 3.66 mg x L(-1) and 11.09 mg x L(-1) during 6 topping time, and those in petiole, stem were between 2.20-5.26 mg x L(-1) and 4.03-7.79 mg x L(-1), respectively. The rations of average flavonoid contents in leaf, petiole and stem to the total contents of vine tips among 3 varieties during their whole topping periods were 46.71%, 20.65% and 32.63%, respectively. The contents during earlier topping time were higher than those of later periods. The variance analysis of flavonoid contents revealed that there was significant difference between different varieties, parts and time of topping and significant interactions among varieties, parts and time of topping.The results of the study indicate that the contents of flavonoid should be considered for the breeding, cultivation and industrialization of sweetpotato for vegetable-use.
Atropa belladonna L. is the commercial plant to produce tropane alkaloids including hyoscyamine and scopolamine, which are widely used as anticholinergic agents. In the present study, the genes encoding the key enzymes including putrescine N-methyltransferase (PMT) and hyoscyamine 6 �-hydroxylase (H6H) were simultaneously overexpressed in transgenic hairy root cultures of A. belladonna . All of the nine transgenic hairy root lines ovexpressing both pmt and h6h produced tropane alkaloids at higher levels. The best line T3 produced 2.2 mg/g dry weight (DW) hyoscyamine, which was about 11 times more than that in non-transgenic hairy root cultures and 24 times more than that in the wild type (intact A. belladonna ). Simultaneously, T3 produced 1.0 mg/g DW scopolamine, which was five times more than that in untransgenic hairy root cultures and four times more than that in the wild type. This is the first report of engineering the tropane alkaloids biosynthetic pathway via overexpressing both pmt and h6h in A. belladonna and the result demonstrated that the metabolic engineering strategy of BREAKING can facilitate accumulation of tropane alkaloids in A. belladonna . Further, it is also proved that transgenic hairy root cultures of A. belladonna can be used as bioreactor to produce pharmaceutical tropane alkaloids.
The results of identifying the productivity and essential economical characteristics of a newly-breeding variety of introduced sweetpotato named Sushu192 were introduced in this paper.In the regional test in Chongqing and Yangtze River district from 2000 to 2002,the yield of the fresh tuberous root of sushu192 increased 13.86%～34.51%,the dry matter yield respectively increased 7.54% and decreased 8.81%,the fresh tuberous root and vine yield increased 16.54%,the starch yield increased 7.45%,the vine yield decreased 1.00% than those of Nanshu88.In the production test in 2002,the fresh tuberous root yield increased and the dry matter yield decreased compared with those of Nanshu88 as well.Sushu 192 has good bud bursting and early-tuberous-growing,easy storing properties,highly the rate of weight of 100g tuberous root and over in total tuberous root,with orange color inner of tuberous root.So,it is especially fit for planting in Chongqing as a raw material to produced candied fruit and feed sweet potato variety.
Anthocyanins are water-soluble flavonoid pigments that play a crucial role in plant growth and metabolism. They serve as attractants for animals by providing plants with red, blue, and purple pigments, facilitating pollination and seed dispersal. The fruits of solanaceous plants, tomato (Solanum lycopersicum) and eggplant (Solanum melongena), primarily accumulate anthocyanins in the fruit peels, while the ripe fruits of Atropa belladonna (Ab) have a dark purple flesh due to anthocyanin accumulation. In this study, an R2R3-MYB transcription factor (TF), AbMYB1, was identified through association analysis of gene expression and anthocyanin accumulation in different tissues of A. belladonna. Its role in regulating anthocyanin biosynthesis was investigated through gene overexpression and RNA interference (RNAi). Overexpression of AbMYB1 significantly enhanced the expression of anthocyanin biosynthesis genes, such as AbF3H, AbF3′5′H, AbDFR, AbANS, and Ab3GT, leading to increased anthocyanin production. Conversely, RNAi-mediated suppression of AbMYB1 resulted in decreased expression of most anthocyanin biosynthesis genes, as well as reduced anthocyanin contents in A. belladonna. Overall, AbMYB1 was identified as a fruit-expressed R2R3-MYB TF that positively regulated anthocyanin biosynthesis in A. belladonna. This study provides valuable insights into the regulation of anthocyanin biosynthesis in Solanaceae plants, laying the foundation for understanding anthocyanin accumulation especially in the whole fruits of solanaceous plants.
Hyoscyamine and scopolamine, belonging to medicinal tropane alkaloids (MTAs), are potent anticholinergic drugs. Their industrial production relies on medicinal plants, but the levels of the two alkaloids are very low in planta. Engineering the MTA's production is an everlasting hot topic for pharmaceutical industry. With understanding the MTA's biosynthesis, biotechnological approaches are established to produce hyoscyamine and scopolamine in an efficient manner. Great advances have been obtained in engineering MTA's production in planta. In this review, we summarize the advances on the biosynthesis of MTAs and engineering the MTA's production in hairy root cultures, as well in plants. The problems and perspectives on engineering the MTA's production are also discussed.
Atropa belladonna is a medicinal plant and an important source for the commercial production of tropane alkaloids (TAs), such as scopolamine and hyoscyamine, which are used clinically for their anticholinergic properties. In this study, we identified 16 metallocarboxypeptidase inhibitor (MCPI) genes from A. belladonna (AbMCPIs), which are grouped into three subgroups based on phylogenetic relationships and are distributed across 10 chromosomes. Promoter analysis showed that most cis-regulatory elements were related to defense and stress responses, such as drought, low-temperature, ABA (abscisic acid), GA (gibberellin), auxin, light and MeJA responsiveness. A gene encoding a putative metallocarboxypeptidase inhibitor (AbMCPI8) is cloned from A. belladonna and characterized. AbMCPI8 shows similar tissue expression pattern to TA biosynthesis genes such as AbPMT, AbAT4, AbTRI, etc., with exclusive expression in the roots. When AbMCPI8 is silenced by virus-induced gene silencing (VIGS), the root growth is markedly inhibited and the production of hyoscyamine and scopolamine is significantly reduced. Our findings indicate a positive role of AbMCPI8 in root development, which could positively affect TA production in A. belladonna.
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