Effect Of Environmental Factors On The Growth And Solanesol Metabolism In Tobacco

Tobacco is an important economic crop in China, which produces various and abundant secondary metabolites including polysaccharides, polyphenols, terpenes and so on. Solanesol is a kind of polyterpene alcohol of great economic and medical value.Like other plants, tobacco goes though its life in a dynamically changing environment. The process of its growth and secondary metabolism is inevitably affected by natural and human factors. In this article, we investigated the effects of light intensity, light quality and rare earth elements on the growth and solanesol metabolism of tobacco.When reducing light intensity appropriately by mild shading, photosynthetic rate and the accumulation of photosynthetic pigments and solanesol were increased, while chlorophyll a/b ratio declined. Severe lack of light impaired photosynthetic rate, photosynthetic pigments and the growth of tobacco significantly. Farnesyl pyrophosphate synthase (FPS) gene (fps) expression was also detected by Real-Time PCR but the relationship between the solanesol synthesis and fps expression needs further study.Light quality experiment showed that long-wavelength light (red and yellow film shading) promoted the biomass accumulation, photosynthetic rate and chlorophyll content, but chlorophyll a/b ratio was decreased. In addition, solanesol production and fps expression increased as well under red and yellow film shading. UV radiation led to upregulation of fps and solanesol production, but not the photosynthetic rate and photosynthetic pigments. The expression level of fps was significantly higher in the late stage than the previous. However solanesol content and fps expression was not completely consistent.As rare earth elements, lanthanum nitrate (La(NO3)3) and cerium nitrate (Ce(NO3)3) treatment elevated photosynthetic rate, photosynthetic pigments, plant biomass and solanesol content under appropriate dose. When La(NO3)3and Ce(NO3)3 was applied with300-700μmol/L and100-500μmol/L respectively, solanesol content in tobacco leaf increased in a dose-dependent manner. Real-Time PCR analysis showed that rare earth elements attenuated fps expression.