Is polyphenol induction simply a result of altered carbon and nitrogen accumulation?

Abstract

Carbon translocation in plants is shaped by phyllotaxis and regulated by source/sink interactions that respond to the demands of growth and defense. We have studied this extensively in poplar saplings, and recently showed that unlike carbon import, nitrogen is not translocated to sink leaves in response to application of jasmonic acid. Here we report that this is also true for young trees in the field. We discuss the importance of transport processes in establishing local C:N ratios, and suggest that the JA-induced flow of C but not N to sink tissues, and their corresponding increases in C-based defenses, may simply reflect a plant adaptation to handle excess reduced carbon and energy.

Keywords: 13C; 15N; Populus; carbon and nitrogen balance; invertase; jasmonate (JA); polyphenols; sink strength.

Figure 1. Import of ¹⁵N to lateral branches of four-year old hybrid poplar trees over a four day period. JA-treated lateral branches did not import additional ¹⁵N as a component of the defense responses. In fact, ¹⁵N import was lower in these branches (closed circles) compared with control branches located on the same trees (open circles). Points represent the mean import of 4–5 branches with +/1 SE error bars. At each time point, import was compared via two-tailed t-tests. * indicates p < 0.10.