Trade-off between photosynthesis and stress tolerance: the role of foliar anatomy and the antioxidant system

Abstract

[eng] Humanity has prioritized the selection of characters that allowed greater productivity since the domestication of crops approximately 12,000 years ago. However, considering the threat of climate change for agriculture, genetic improvement no longer only considers the improvement of productive traits but also of those that determine tolerance to stress. There is a generalized hypothesis that argues that productivity and stress tolerance follow an inverse relationship, that is, as productivity increases, stress tolerance decreases and vice versa. Considering the increase in the world population, it is predicted that being able to feed all the people of the planet is the greatest biotechnological and socioeconomic challenge of recent times. Since the resources available for plants are finite, the carbon assimilated from the environment through photosynthesis can be invested in plant growth, reproduction or defense in a highly balanced manner to maximize plant fitness. Additionally, maximum photosynthetical capacity (Amax) is driven by investments in leaf anatomy and the photosynthetic metabolism, these investments can also compete with resources needed for plant stress tolerance as well at anatomical level the antioxidant metabolism. Both levels define stress tolerance, as well as the photosynthetic process itself. In this way, in this TFM we proceeded with the characterization of 16 species of plants from different environments of the world, with some from the most extreme environments on the planet, such as the Arctic or Antarctica. A series of growth or photosynthetic measurements were carried out under optimal conditions for each of the species: photosynthetic measurements, freezing test, desiccation test, anatomical characterization, and different biochemical parameters. We observed that polar species usually tend to obtain higher stress tolerance values than "Mediterranean" and "Model & Crops" species, but however their photosynthetical capacity was lower than the others. Our results showed a new trade-off between Amax and dehydration tolerance, which are related with anatomical parameters as Sc/S and Tchl. Interestingly, we did not find a trade-off relationship with biochemical parameters as chlorophyll, flavanols and anthocyanin contents. Altogether, these results open the opportunity to establish the relationship between productivity and stress tolerance, which continues to be a global biotechnological challenge today.