Reduced glucosinolate content in oilseed rape (Brassica napus L.) by random mutagenesis of BnMYB28 and BnCYP79F1 genes.

The presence of anti-nutritive compounds like glucosinolates (GSLs) in the rapeseed meal severely restricts its utilization as animal feed. Therefore, reducing the GSL content to < 18 µmol/g dry weight in the seeds is a major breeding target. While candidate genes involved in the biosynthesis of GSLs have been described in rapeseed, comprehensive functional analyses are missing. By knocking out the aliphatic GSL biosynthesis genes BnMYB28 and BnCYP79F1 encoding an R2R3 MYB transcription factor and a cytochrome P450 enzyme, respectively, we aimed to reduce the seed GSL content in rapeseed. After expression analyses on single paralogs, we used an ethyl methanesulfonate (EMS) treated population of the inbred winter rapeseed 'Express617' to detect functional mutations in the two gene families. Our results provide the first functional analysis by knock-out for the two GSL biosynthesis genes in winter rapeseed. We demonstrate that independent knock-out mutants of the two genes possessed significantly reduced seed aliphatic GSLs, primarily progoitrin. Compared to the wildtype Express617 control plants (36.3 µmol/g DW), progoitrin levels were decreased by 55.3% and 32.4% in functional mutants of BnMYB28 (16.20 µmol/g DW) and BnCYP79F1 (24.5 µmol/g DW), respectively. Our study provides a strong basis for breeding rapeseed with improved meal quality in the future.

The mutagenic potential of madder root in dyeing processes in the textile industry.

The roots of Rubia tinctorum L. have a long tradition of being used in dyeing processes of textiles from centuries ago until the present time. The colouring principles belong to the class of hydroxyanthraquinones. Concern arose because several of these compounds were recognised as mutagenic in vitro and even carcinogenic in rodents. To assess the possible risk to humans caused by coloured textiles, mutagenicity was investigated with two madder root samples of different origin (Iran and Bhutan) along the entire dyeing process from root extracts to the dyed wool. The Salmonella/microsome test (Ames assay) with the strains TA98, TA100 and TA1537 was used. Significant mutagenic effects could be detected in madder root extracts and also in the final product, the dyed wool. Madder root from Iran showed considerably higher mutagenic responses than samples from Bhutan. Analytical investigations of the extracts by HPLC showed the presence of a spectrum of anthraquinones typical for madder root. Three mutagenic compounds, lucidine, rubiadine and purpuroxanthine, together with the non-mutagenic alizarine could be detected. The mutagenic response of the different samples was positively correlated with the concentration of the mutagenic anthraquinones, and with lucidine in particular. Based on these investigations a risk to dye-house workers and users of textiles dyed with R. tinctorum must be anticipated.