47th TWC, Tob. Work. Conf., 2016, abstr. 54

Topping and suckercide treatments trigger global changes in gene expression in tobacco

(1) University of Kentucky, Lexington KY USA; (2) R.J. Reynolds Inc., Winston Salem, NC USA

Topping and control of formation of suckers are common agronomic practices that significantly impact the yield and quality of various crop plants. Application of suckercides to plants following topping is a common method for sucker control. Tobacco (Nicotiana tabacum), like many other crop plants, is commonly topped and treated with suckercides. We performed RNA-sequencing to study the differential gene expression in tobacco that was topped or treated after topping by two chemicals, the local-systemic suckercide, Flupro® (FP), and contact suckercide, Off-Shoot-T® (OS). Transcriptome analysis identified a large number of genes that were differentially expressed in leaves responding to topping, FP-, and OS-treatment, respectively. Among these differentially expressed genes (DEGs), some are common to all three conditions. Hierarchical cluster analysis of the DEGs revealed four groups with distinct expression patterns. DEGs, largely related to wounding and secondary metabolism, exhibited significant upregulation following topping and downregulation after suckercide treatments. DEGs related to photosynthetic processes were repressed following topping as well as suckercide treatments. Comparison of topping and FP-treatment revealed common DEGs, largely related to wound response, hormone signaling, small molecule biosynthesis, and amino acid metabolism. DEGs common to topping and OS treatment were largely related jasmonate biosynthesis and secondary metabolism. Moreover, topping and FP-treatment affect the expression of auxin and cytokinin signaling pathway genes that are probably involved in sucker formation. Our findings suggest that suckecides impact expression of genes related to a number of primary as well as secondary metabolic pathways in plants. The regulatory elements of highly upregulated DEGs can potentially be used for the development of a topping-inducible chemical-free sucker control system. (Reprinted with permission)