RESUMO
Sapindus is an important forest tree genus with utilization in biodiesel, biomedicine, and it harbors great potential for biochemical engineering applications. For advanced breeding of Sapindus, it is necessary to evaluate the genetic diversity and construct a rationally designed core germplasm collection. In this study, the genetic diversity and population structure of Sapindus were conducted with 18 expressed sequence tag-simple sequence repeat (EST-SSR) markers in order to establish a core germplasm collection from 161 Sapindus accessions. The population of Sapindus showed high genetic diversity and significant population structure. Interspecific genetic variation was significantly higher than intraspecific variation in the Sapindus mukorossi, Sapindus delavayi, and combined Sapindus rarak plus Sapindus rarak var. velutinus populations. S. mukorossi had abundant genetic variation and showed a specific pattern of geographical variation, whereas S. delavayi, S. rarak, and S. rarak var. velutinus showed less intraspecific variation. A core germplasm collection was created that contained 40% of genetic variation in the initial population, comprising 53 S. mukorossi and nine S. delavayi lineages, as well as single representatives of S. rarak and S. rarak var. velutinus. These results provide a germplasm basis and theoretical rationale for the efficient management, conservation, and utilization of Sapindus, as well as genetic resources for joint genomics research in the future.
RESUMO
Soapberry (Sapindus mukorossi Gaertn.) pericarps are rich in valuable bioactive triterpenoid saponins. However, the saponin content dynamics and the molecular regulatory network of saponin biosynthesis in soapberry pericarps remain largely unclear. Here, we performed combined metabolite profiling and transcriptome analysis to identify saponin accumulation kinetic patterns, investigate gene networks, and characterize key candidate genes and transcription factors (TFs) involved in saponin biosynthesis in soapberry pericarps. A total of 54 saponins were tentatively identified, including 25 that were differentially accumulated. Furthermore, 49 genes putatively involved in sapogenin backbone biosynthesis and some candidate genes assumed to be responsible for the backbone modification, including 41 cytochrome P450s and 45 glycosyltransferases, were identified. Saponin-specific clusters/modules were identified by Mfuzz clustering and weighted gene coexpression network analysis, and one TF-gene regulatory network underlying saponin biosynthesis was proposed. The results of yeast one-hybrid assay and electrophoretic mobility shift assay suggested that SmbHLH2, SmTCP4, and SmWRKY27 may play important roles in the triterpenoid saponin biosynthesis by directly regulating the transcription of SmCYP71D-3 in the soapberry pericarp. Overall, these findings provide valuable information for understanding the molecular regulatory mechanism of saponin biosynthesis, enriching the gene resources, and guiding further research on triterpenoid saponin accumulation in soapberry pericarps.
Assuntos
Sapindus , Saponinas , Triterpenos , Perfilação da Expressão Gênica , Metaboloma , Sapindus/genética , Sapindus/metabolismo , Saponinas/genética , Transcriptoma , Triterpenos/metabolismoRESUMO
Triterpenoid saponin are important secondary metabolites and bioactive constituents of soapberry (Sapindus mukorossi Gaertn.) and are widely used in medicine and toiletry products. However, little is known about the roles of miRNAs in the regulation of triterpenoid saponin biosynthesis in soapberry. In this study, a total of 3036 miRNAs were identified, of which 1372 miRNAs were differentially expressed at different stages of pericarp development. Important KEGG pathways, such as terpenoid backbone biosynthesis, sesquiterpenoid and triterpenoid biosynthesis, and basal transcription factors were highlighted, as well the roles of some key miRNAs, such as ath-miR5021, han-miR3630-3p, and ppe-miR858, which may play important roles in regulating triterpenoid saponin biosynthesis. In addition, 58 miRNAs might participate in saponin biosynthesis pathways by predicting the targets of those miRNAs to 53 saponin biosynthesis structural genes. And 75 miRNAs were identified to potentially play vital role in saponin accumulation by targeting transcript factor genes, bHLH, bZIP, ERF, MYB, and WRKY, respectively, which are candidate regulatory genes in the pathway of saponin biosynthesis. The results of weighted gene coexpression network analysis (WGCNA) suggested that two saponin-specific miRNA modules and 10 hub miRNAs may participate in saponin biosynthesis. Furthermore, multiple miRNA-mRNA regulatory networks potentially involved in saponin biosynthesis were generated, e.g., ath-miR5021-SmIDI2/SmGPS5/SmbAS1/SmCYP71D-3/SmUGT74G-2, han-miR3630-3p-SmCYP71A-14/SmbHLH54/SmMYB135/SmWRKY32, and ppe-miR858-SmMYB5/SmMYB32. qRT-PCR analysis validated the expression patterns of nine miRNAs and 12 corresponding target genes. This study represents the first comprehensive analysis of miRNAs in soapberry and lays the foundation for further understanding of miRNA-based regulation in triterpenoid saponin biosynthesis.
RESUMO
Sapindus (Sapindus L.) is a widely distributed economically important tree genus that provides biodiesel, biomedical and biochemical products. However, with climate change, deforestation, and economic development, the diversity of Sapindus germplasms may face the risk of destruction. Therefore, utilising historical environmental data and future climate projections from the BCC-CSM2-MR global climate database, we simulated the current and future global distributions of suitable habitats for Sapindus using a Maximum Entropy (MaxEnt) model. The estimated ecological thresholds for critical environmental factors were: a minimum temperature of 0-20 °C in the coldest month, soil moisture levels of 40-140 mm, a mean temperature of 2-25 °C in the driest quarter, a mean temperature of 19-28 °C in the wettest quarter, and a soil pH of 5.6-7.6. The total suitable habitat area was 6059.97 × 104 km2, which was unevenly distributed across six continents. As greenhouse gas emissions increased over time, the area of suitable habitats contracted in lower latitudes and expanded in higher latitudes. Consequently, surveys and conservation should be prioritised in southern hemisphere areas which are in danger of becoming unsuitable. In contrast, other areas in northern and central America, China, and India can be used for conservation and large-scale cultivation in the future.
