Infraspecific variation in trade-offs between resource acquisition and defense in tomato (Solanum lycopersicum)

Background/Question/Methods

Life-history theory predicts that under conditions of limiting resources, plant traits express strong trade-offs that depend on environmental conditions. The suite of trade-offs that has received arguably the most attention, are hypothesized “decisions” made by plants regarding investment in plant defense that come at the expense of plant growth or resource acquisition traits. Understanding and being able to monitor these trade-offs in crops is particularly important for predicting crop performance within and across agricultural landscapes. Here, we seek to detect growth-defense trade-offs across four mutant tomato (Solanum lycopersicum) genotypes selected to differ in their plant defense responses, grown under uniform greenhouse conditions. We then assessed if or how these different genotypes differ in their resource capture traits (namely, leaf mass per area (LMA), leaf nitrogen (N) concentrations, leaf area, and leaf dry matter content (LDMC)). We hypothesized that the genotypes conferring greater defense responses, would be associated with lower leaf N and leaf area, alongside higher LMA and LDMC. In our study, leaf traits were assessed using a full spectrum spectroradiometer such that our study also evaluates if remote sensing, namely hyperspectral imaging, is able to capture resource allocation trade-offs across agricultural landscapes.

Results/Conclusions

The four genotypes assessed in our study differed widely in their leaf traits related to resource capture. Specifically, leaf N concentrations, leaf area, LMA, and LDMC differed significantly across lineages. We detected evidence of trade-offs and covariation among these suites of traits in both bivariate and multivariate trait space: genotypes selected for greater defense responses were associated with higher LMA and LDMC, with all traded-off against leaf N and leaf area. Two key traits that reflect this trade-off—namely leaf N concentrations LMA—were strongly correlated with multiple reflectance spectra. These results indicate that infraspecific variation in leaf traits and their potential correlations with defense investments, are likely observable at larger spatial scales through remote sensing applications.