Genetic strategies for sucker control and evaluation
Tobacco plants exhibit strong apical dominance. Molecular signals from shoot apical meristems (SAM) mediate hormonal signals that effectively inhibit axillary bud growth. Upon SAM removal, loss of hormonal signals enables axillary buds to grow into new shoots (or “suckers”) resulting in loss of yield and leaf quality. Therefore, development of tobaccos with delayed, limited or no suckering would reduce tobacco production cost, increase yield and improve quality. Different strategies were employed to identify candidate genes associated with sucker formation. Functional analysis of selected genes and their promoters were studied. GUS markers were used to evaluate the tissue and/or plant development specificity of targeted promoters. Axillary bud specific promoters were identified and fused with selected target genes for axillary bud expression. Transgenic plants were grown to layby, 8-10 leaf stage and then topped and evaluated for reduced sucker phenotypes. Over-expression of candidate gene(s) with axillary bud specific promoter(s) resulted in suppression of axillary bud growth and branch development up to four weeks after topping. The mechanisms for axillary meristem initiation and development are under investigation.