Transgenic and Mutation-Based Suppression of a Berberine Bridge Enzyme-Like (BBL) Gene Family Reduces Alkaloid Content in Field-Grown Tobacco

摘要: Motivation exists to develop tobacco cultivars with reduced nicotine content for the purpose of facilitating compliance expected product regulations that could mandate lowering levels per se, or reduction carcinogenic alkaloid-derived specific nitrosamines (TSNAs). A berberine bridge enzyme-like (BBL) gene family was recently characterized N. tabacum and found catalyze one final steps in pyridine alkaloid synthesis this species. Because acts downstream biosynthetic pathway, it may represent an attractive target genetic strategies objective reducing field-grown tobacco. In research, we produced transgenic doubled haploid lines cultivar K326 carrying RNAi construct designed reduce expression BBL family. Field-grown functional constructs exhibited average cured leaf 0.684%, comparison 2.454% untransformed control. Since numerous barriers would need be overcome commercialize cultivars, subsequently pursued a mutation breeding approach identify EMS-induced mutations three most highly expressed isoforms Field evaluation individuals possessing different homozygous combinations truncation BBLa, BBLb, BBLc indicated range phenotypes produced, triple knockout genotype exhibiting greater than 13-fold percent total alkaloids. The novel source variability described here useful future varied levels.