Fast tracking alien gene discovery by molecular markers in a late flowering Chinese cabbage-cabbage translocation line‘AT7–4'

Flowering time is an important agronomic trait of Chinese cabbage with late flowering being a primary breeding objective.In our previous work,we obtained Chinese cabbage-cabbage translocation lines that contained several beneficial cabbage genes.Cabbage-specific molecular markers show that these genes were coming from chromosome C01 of cabbage.In this study,we investigated the inheritance of flowering time in a couple of translocation lines and analyzed the transmission rate of molecular markers in the offspring.Consequently,we obtained the late flowering Chinese cabbage-cabbage translocation line‘AT7–4’in which the flowering time was later than that of‘85–1’by about 7 days under 4-week vernalization.Based on previous studies of the genomes of Chinese cabbage and cabbage,we located the cabbage-specific molecular markers that were closely linked at the top of the chromosome A01 in the F2mapping population generated by self-crossing F1s derived from a cross between the translocation line‘AT7–4’and Chinese cabbage‘14–36’.Five flowering-related genes in the alien fragment were found by functional annotation and their molecular markers were developed.This study lays the foundation for the future improvement of Chinese cabbage varieties using A-C translocation lines.

Rapid one-step enzyme immunoassay and lateral flow immunochromatographic assay for colistin in animal feed and food

Background:Colistin(polymyxin E)is a kind of peptide antibiotic which has been approved in animal production for the purposes of disease prevention,treatment,and growth promotion.However,the wide use of colistin in animal feed may accelerate the spread of colistin-resistance gene MCR-1 from animal production to human beings,and its residue in animal-origin food may also pose serious health hazards to humans.Thus,it is necessary to develop corresponding analytical methods to monitor the addition of colistin in animal feed and the colistin residue in animal-origin food.Results:A one-step enzyme-linked immunosorbent assay(ELISA)and a lateral flow immunochromatographic assay(LFIA)for colistin were developed based on a newly developed monoclonal antibody.The ELISA showed a 50%inhibition value(IC50)of 9.7 ng/m L with assay time less than 60 min,while the LFIA had a strip reader-based detection limit of 0.87 ng/m L in phosphate buffer with assay time less than 15 min.For reducing the non-specific adsorption of colistin onto sample vial,the components of sample extraction solution were optimized and proved to greatly improve the assay accuracy.The spiked recovery experiment showed that the recoveries of colistin from feed,milk and meat samples were in the range of 77.83%to 113.38%with coefficient of variations less than 13%by ELISA analysis and less than 18%by LFIA analysis,respectively.Furthermore,actual sample analysis indicated that the two immunoassays can produce results consistent with instrumental analysis.Conclusions:The developed assays can be used for rapid qualitative or quantitative detection of colistin in animal feed and food.