2021 journal article
Constitutive activation of nitrate reductase in tobacco alters flowering time and plant biomass
SCIENTIFIC REPORTS, 11(1).
MeSH headings : Biomass; Environment; Flowers / genetics; Gene Expression Regulation, Plant; Gene-Environment Interaction; Genetic Association Studies; Nitrate Reductase / genetics; Nitrate Reductase / metabolism; Organ Specificity / genetics; Plant Development / genetics; Tobacco / physiology; Transcriptional Activation
TL;DR:
It is shown that plants expressing a constitutively active NR construct, designated 35S:S523D-NR, display an early-flowering phenotype that is also associated with a substantial reduction in plant biomass, and the mechanism by which yield was restored differed markedly between the two crosses.
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UN Sustainable Development Goal Categories
2. Zero Hunger
(Web of Science)
3. Good Health and Well-being
(OpenAlex)
Source: Web Of Science
Added: March 22, 2021
AbstractPyridine alkaloids produced in tobacco can react with nitrosating agents such as nitrite to form tobacco-specific nitrosamines (TSNA), which are among the most notable toxicants present in tobacco smoke. The market type known as burley tobacco is particularly susceptible to TSNA formation because its corresponding cultivars exhibit a nitrogen-use-deficiency phenotype which results in high accumulation of nitrate, which, in turn, is converted to nitrite by leaf surface microbes. We have previously shown that expression of a constitutively activated nitrate reductase (NR) enzyme dramatically decreases leaf nitrate levels in burley tobacco, resulting in substantial TSNA reductions without altering the alkaloid profile. Here, we show that plants expressing a constitutively active NR construct, designated 35S:S523D-NR, display an early-flowering phenotype that is also associated with a substantial reduction in plant biomass. We hypothesized that crossing 35S:S523D-NR tobaccos with burley cultivars that flower later than normal would help mitigate the undesirable early-flowering/reduced-biomass traits while maintaining the desirable low-nitrate/TSNA phenotype. To test this, 35S:S523D-NR plants were crossed with two late-flowering cultivars, NC 775 and NC 645WZ. In both cases, the plant biomass at harvest was restored to levels similar to those in the original cultivar used for transformation while the low-nitrate/TSNA trait was maintained. Interestingly, the mechanism by which yield was restored differed markedly between the two crosses. Biomass restoration in F1 hybrids using NC 645WZ as a parent was associated with delayed flowering, as originally hypothesized. Unexpectedly, however, crosses with NC 775 displayed enhanced biomass despite maintaining the early-flowering trait of the 35S:S523D-NR parent.