Polyphenol Accumulation in Chlorophyll Mutants of Tobacco under Two Cultural Practices

Quantitative variation in plastid pigments and polyphenols during leaf growth and after curing have been studied with several chlorophyll-deficient genotypes of tobacco. Under culture for flue-cured tobacco, the chlorophyll-deficient pale-yellow (NC95-Py) and yellow-green (SC58-yg) lines did not differ in polyphenol accumulation from the corresponding normal green recurrent parents NC95 and SC58. A negative correlation was evident between concentrations of polyphenol and chlorophyll. Decrease of the latter during leaf growth was accompanied with a decline of PPO and PRO activities. When the chlorophyll-deficient genotypes were grown under conditions for Burley tobacco, concentrations of chlorophyll and polyphenol maintained a steady level and were positively correlated, while the oxidases tended to increase. Burley 21 contained the lowest amount of polyphenols among the chlorophyll mutants, although the low chlorophyll content of its mature leaves was comparable to that of SC58-yg. Use of cultural practices for flue-cured tobacco caused an accumulation of polyphenols in green leaves. There was a greater loss of soluble polyphenols during air-curing than during flue-curing. Results indicate that the interaction of cultural practices with chlorophyll-deficient genes affects the metabolism of chlorophylls and polyphenols during leaf growth and maturation. Introduction of these genes into tobacco cultivars may provide a means of enhancing uniformity of leaf maturity and modifying certain leaf chemical constituents.