D3389: Comparative study of aphid infestation in low alkaloid and standard alkaloid tobacco in the presence/absence of CBT-diols

Proposed FDA regulations may require significant reduction of the nicotine content (< 0.5mg/g) of tobacco products. Lowering the nicotine concentration raises concern about aphid infestation in low-nicotine lines. There is evidence that multiple chemicals play role in plant-pest interaction such as nicotine, cembratriene-diols (CBT-diols) and sugar esters. Nicotine and CBT-diols, may have opposite effects on aphid infestation: nicotine may be toxic to aphids while the CBT-diols may attract them to favor infestation. The objective of this proposal is to compare the effect of two nicotine levels (low and standard) on the aphid infestation in the presence or absence of CBT-diols in the burley tobacco cultivar TN 90LC and its low-alkaloid version LA TN90. The goal of the second stage of the proposal was to identify stable T1 and T2 transgenic lines with suppressed CBT-diol synthesis (GC-MS verified). Selected T0 transgenic plants were self-pollinated and T1 generation plants were used for bioassays with aphids in green house conditions. During 2020-2021, we employed both choice and no-choice tests to document the responses of Myzus persicae (Sulzer) toward the high and low alkaloid burley lines and their CBT-diol knockdown transgenic lines to comprehensively assess the effect of both compounds on aphid infestation. Our combined results from mortality, fecundity, and preference bioassays showed no significant differences between presence or absence of CBT-diols tobacco plant lines, either TN90LC or LA TN90.