Brassica rapa L. originated from China, whose qualify analysis and evaluation was highly important for its development and utilization.
In this study, rapeseed was used as the research object. After grinding extraction and ion exchange column treatment, the glucosinolate extract was obtained. The high performance liquid chromatography (HPLC) was utilized to determine and analyze the content and components of glucosinolates in 323 B. rapa L. accessions.
The total content of glucosinolates in 323 B. rapa L. samples ranged from 26.19 to 238.21 µmol∙g-1, with an average of 137.22 µmol∙g-1. A total of 9 glucosinolate components were identified, consisting of five aliphatic glucosinolates (progoitrin, glucoraphanin, gluconapoleiferin, gluconapin and glucobrassicanapin), three indole glucosinolates (4-hydroxyglucobrassicin, glucobrassicin, and 4-methoxyglucobrassicin), and one aromatic glucosinolate (gluconasturtiin). The predominant glucosinolate in B. rapa L. was gluconapin, which belonged to the aliphatic glucosinolate group. It had an average concentration of 122.68 µmol∙g-1, making up 93.71% of the aliphatic glucosinolate content and 89.40% of the overall glucosinolate content. The comparison of the total glucosinolate content in accessions originated from various ecological zones indicated that the Yangtze River basin had the highest glucosinolate content, followed by the Huanghuai region, Xizang, and Gansu accessions. Among accessions, the content of 4-hydroxyglucobrassicin and glucobrassicin in Gansu accessions was more than that in accessions originated from the other three ecological zones. The content of gluconapin in Gansu accessions was the lowest compared to other accessions. The content of indole glucosinolates exhibited significant variations based on their sensitivity to temperature, with the highest levels observed in harsh winter types (11.50 µmol∙g-1), followed by winter types (7.60 µmol∙g-1), semi-winter types (6.77 µmol∙g-1), and spring types (3.87 µmol∙g-1). The findings demonstrated that, the content of progoitrin and indole glucosinolates differed significantly among the germplasm collection used in this study. Six accessions with high-indolyl glucoside content (ranging from 5.86 to 13.81 µmol∙g-1) and three accessions with progoitrin content (ranging from 50.14 to 68.38 µmol∙g-1) were selected by screening.
Aliphatic glucosinolates were the primary components of glucosinolates in B. rapa L., with gluconapin being the predominant component. The glucosinolate components exhibited significant variations depending on the genotype of the accessions. Different genotypes were selected based on their concentration of ultra-high glucosinolate, high indole glucosinolate, and high progoitrin.