Isolation of wheat mutants with higher grain phenolics to enhance anti-oxidant potential.

Present in many plant foods, biogenic phenolic compounds are important bioactive phytonutrients with high anti-oxidant activity and thereby are praised for their health-promoting properties. However, current food nutrient improvement by high phenolic content in staples is limited by the shortage of genetic resources rich in phenolic compounds. To resolve this obstacle, we developed a non-destructive massive analytical approach to screen wheat phenolic mutants. In grains, multiple mutant lines showed significantly higher contents of flavonoids or cell wall-bound phenolic esters. Moreover, five mutants showed higher anti-oxidant potentials in wall-bound phenolic compounds ranging from 15% to 20%, with the maximal close to natural black wheat. In contrast to black wheat, two mutants accumulated higher phenolic compounds in the endosperm. lrf4 was mapped by BSR to a concentrated genomic region in the short arm of chromosome 1A. The present work represents an efficient high-throughput strategy to increase wheat anti-oxidant potential through traditional mutagenesis.

Comparative genomic analysis of Mycobacterium neoaurum MN2 and MN4 substrate and product tolerance.

The microbial bioconversion of sterols can afford valuable steroid precursors, such as 4-androstene-3,17-dione (AD) and androsta-1,4-diene-3,17-dione (ADD). The Mycobacterium neoaurum MN4 mutant strain can produce AD in high yield and can tolerate a higher concentration of the substrate phytosterol than the parent strain M. neoaurum MN2. In order to further investigate the mechanisms underlying the enhanced substrate and product tolerance, we performed a genomic analysis of the MN2 and MN4 strains. The genomes were sequenced using a high-throughput approach and analyzed using software for genome assembly, gene prediction and functional annotation, KEGG (Kyoto Encyclopedia of Genes and Genomes) annotation, COG (cluster of orthologous) group cluster analysis, GO cluster analysis, and SNP detection and annotation. Based on comparative genomics, 184 mutations were identified in MN4, the average variant rate of 1 variant every 27,249 bases, with a TS/TV value of 0.5877 and missense mutations in one key sterol degradation genes (ChoM1) and four side chain degradation genes that encode enzymes catalysing ß-oxidation. The results suggest the high AD yield might be due to mutation of ChoM and genes encoding FadE, FadB and FadA ß-oxidation enzymes. This study provides a theoretical basis for further functional genomics analysis and heterologous production of M. neoaurum MN2 secondary metabolites.