Sucker control through biotechnology
Tobacco plants exhibit strong apical dominance that effectively inhibits axillary bud development. However, upon shoot apical meristem removal (topping), loss of apical dominance quickly allows axillary buds to grow (suckers) resulting in yield loss and reduced leaf quality. Therefore, tobacco varieties exhibiting inhibited or eliminated sucker growth would reduce production cost, increase yields and improve quality. Molecular profiling of axillary buds before and after topping revealed multiple genes associated with axillary bud development. More than forty axillary bud developmental genes were evaluated for phenotypic impact via up-regulation and/or down-regulation in transgenic tobaccos. Several of these developmental genes produced the desired reduced sucker phenotype. Six associated developmental gene promoters were also tested for axillary bud tissue specificity and efficacy using GUS/GFP reporter genes. An axillary bud tissue specific promoter with high efficacy was fused independently with several selected developmental genes and inhibitory genes and their phenotypic impact was examined. Over-expression/down regulation of the developmental genes and inhibitory genes with the axillary bud tissue specific promoter resulted in suppression of axillary bud growth after topping. Our data show that combination of an axillary bud tissue specific promoter with a selected group of genes can prevent or delay sucker development after topping in tobacco.