Zihao Li

Polygonatum sibiricum ( P. sibiricum ), rich in saponins, possesses extremely high medicinal value. However, inconsistent saponin levels in naturally grown P. sibiricum hinder its quality control assessments and industrial progress. In this study, we applied salicylic acid (SA) to P. sibiricum and measured the content changes of 11 saponins. Transcriptome sequencing was used to explore the molecular mechanism of saponin biosynthesis. Key saponin biosynthesis genes were identified and subsequently characterized through phylogenetic and structural analyses. The results showed that saponin contents changed significantly after SA treatment. We characterized six key gene families: SQLEs (squalene epoxidases, EC: 1.14.14.17), DXSs (1‐deoxy‐D‐xylulose‐5‐phosphate synthases, EC: 2.2.1.7), FDPSs (farnesyl diphosphate synthases, EC: 2.5.1.1/2.5.1.10), CYP710As (cytochrome P450, family 710, subfamily A; sterol 22‐desaturase, EC: 1.14.19.41), HMGCSs (3‐hydroxy‐3‐methylglutaryl‐CoA synthases, EC: 2.3.3.10), and SMT1s (sterol methyltransferase 1s, EC: 2.1.1.41), whose phylogenetic analysis revealed the unique evolutionary position of saponin biosynthesis genes. Furthermore, structural prediction and molecular docking revealed functional adaptations of SQLEs. In summary, our findings decipher the molecular mechanisms of SA‐induced saponin biosynthesis in P. sibiricum , which can boost its medicinal value.

Anthocyanins can enhance the nutritional and market value of Dioscorea alata L. They are synthesized in a tissue-specific manner in the peel and flesh of tubers in some Dioscorea alata L. varieties, yet the regulatory mechanisms behind this remain unclear. In order to identify the genes involved in anthocyanin synthesis between the skin and flesh of D. alata, three varieties exhibiting distinct anthocyanin phenotypes were studied. A comprehensive analysis of the skin and flesh was conducted to identify the presence of anthocyanins. Three identical anthocyanins were identified in both the skin and the flesh: Alatanin C, Cya-3-O(2-O-glucosyl) glu, and Cya-3-O(6-O-sinapoyl) sop-5-O-glu. To investigate the anthocyanin biosynthesis pathways in purple D. alata skin and flesh, transcriptome sequencing was performed on both tissues. This analysis identified eight anthocyanins in the skin and fifteen in the flesh. Cyanidin-type anthocyanins were found to be the most abundant type of anthocyanin in both skin and flesh. Subsequent identification of 30 key genes associated with anthocyanin biosynthesis revealed 4CL (4-coumarate CoA ligase) and DFR (dihydroflavonol 4-reductase) as potential key regulators of anthocyanin variation between skin and flesh. This study is of considerable theoretical and practical significance for the genetic enhancement of anthocyanin traits in D. alata.

Taro (Colocasia esculenta (L.) Schott) is the fifth largest rhizome crop, and it is widely distributed in tropical and subtropical areas in the world. Vegetative propagation with virus-infected corms can lead to cultivar degradation, yield decline, and quality deterioration. In this study, the shoot apical meristems excised from taro corms infected with dasheen mosaic virus, which belongs to the genus Potyvirus in the family Potyviridae, were cultured and treated with exogenous abscisic acid and high sucrose concentrations to induce micro-corm formation. Subsequently, candidate genes involved in micro-corm expansion were screened via transcriptome sequencing analysis. The results revealed that the shoot apical meristems could grow into adventitious shoots on the medium 1 mg/L 6-benzylaminopurine + 0.3 mg/L 1-naphthaleneacetic acid, and reverse transcription–polymerase chain reaction detection indicated that dasheen mosaic virus had been successfully eliminated from the test-tube plantlets. Moreover, 8% sucrose or 3% sucrose + 5 μM abscisic acid likewise induced taro corm formation, and genes related to cell division and the cell cycle, as well as starch and sucrose metabolism pathways, were significantly enriched during taro corm expansion. Furthermore, the cyclin-dependent kinases genes, cell cycle protein kinase subunit genes, and cyclin B2 genes, which are related to cell division and the cell cycle, were upregulated with abscisic acid treatment on the 3rd day. The sucrose synthase genes, β-amylase genes, glycogen branching enzyme genes, and soluble starch synthase genes, which are related to starch and sucrose metabolism, were upregulated on the 15th day, indicating that cell division largely occurs during taro corm formation, whereas carbohydrates are synthesized during taro corm expansion.

Taro (Colocasia esculenta (L.) Schott) is a tropical tuber crop whose underground corms are used as an important staple food. However, due to a lack of molecular markers, the genetic diversity, germplasm identification, and molecular breeding of taro are greatly limited. In this study, high-density InDel-SSR molecular markers covering the whole genome were developed based on the resequencing data of taro core germplasm. A total of 1,805,634 InDel-SSR loci were identified, and 219 highly polymorphic markers with an average polymorphism information content PIC value of 0.428 were screened. Furthermore, a genetic diversity analysis of 121 taro germplasm resources was conducted based on 219 markers, dividing the resources into three groups. In addition, an association analysis showed that, of the multiple InDel-SSR markers, g13.52 and g12.82 were significantly associated with leaf area and average cormel weight, respectively; the candidate genes CeARF17 (EVM0014444) and CeGA20ox (EVM0001890) were related to cormel expansion; and we excavated the candidate genes CeXXT2 (EVM0016820) and CeLOG1 (EVM0017064), which regulate leaf development. The InDel-SSRs and candidate genes identified in this study are expected to provide important support for genetically improving and breeding new varieties of taro.