Molecular identification of DNA barcoding of Leguminous toxic species and quantitative analysis by ELISA kits

Some edible Leguminous are toxic when raw, and the Chinese are particularly fond of beans, so Leguminous poisoning is very common in China. Rapid and accurate identification of poisoned species and determination of their toxic components would better assist physicians in treating patients. However, traditional morphology-based identification methods possess many limitations. DNA barcoding technique is a new species identification technique developed in recent years, which is expected to make up for the shortcomings of traditional morphological identification. In this study, a comprehensive evaluation system based on DNA barcoding and ELISA kits was attempted. A total of 30 Leguminous toxic plants were collected, involving 9 genera and 10 species. We used simulated gastric fluid (SGF) to simulate the human gastric environment. Three markers (rbcL, trnH-psbA, and ITS) were amplified and sequenced for all untreated and 15 mock-digested samples. The validity of DNA barcoding for species identification was assessed using the Basic Local Alignment Search Tool (BLAST) method and the tree construction method. The levels of three toxic components (saponin, phytoagglutin and trasylol) were determined in all samples using ELISA kits. The amplification success rate of all three regions was high (rbcL 96.67%, trnH-psbA 100%, and ITS 100%), but the sequencing of the trnH-psbA region was less satisfactory (66.67%), and SGF had a significant impact on the sequencing of the ITS region (After 40 min of SGF treatment, the sequencing success rate decreased by 46.67%). The samples from different species and origins contained different levels of toxic components, and the levels of all three substances decreased significantly after undergoing SGF digestion. After 1 h of SGF treatment, the saponin content decreased to 0–8.60% in untreated content (PHA decreased to 8.62–36.88%, trasylol decreased to 4.70–47.06%). The current results suggest that DNA barcoding has great potential for rapid identification of Leguminous poisoning in clinical settings. Toxins are probably not detectable in the patient for longer periods of poisoning. We recommend DNA barcoding technology as a first step for rapid screening and combined with toxin analysis for clinical diagnosis.