A trade-off between allocated resources for photosynthesis and stress
tolerance is generally observed in nature. Thus, the search for outlier
species breaking this trend is an interesting approach to identity new
mechanisms for plant breeding purposes. Hypothetically, outlier
extremophyte species present a distinctive arrangement of physiological
functions that favor stress tolerance mechanisms without jeopardizing
investment allocation into photosynthesis. We explored this trade-off,
analyzing twenty-one plant species for desiccation tolerance, and
photosynthetic capacity, under the extreme arid environments of the
Atacama Desert and the Surire Salar in the Chilean Altiplano. Most of
the studied species followed the trade-off tendency, however, we did
find one outlier species, Prosopis tamarugo. To study the
mechanisms involved in this atypical response, the Prosopis genus
was analyzed more deeply. Our results suggest that the outlier response
of P. tamarugo is multifactorial. This species presented a high
photochemistry activity, associated with a higher synthesis of
chlorophylls, photoprotective pigments, and complex antioxidant
molecules. Moreover, the synthesis of no-nitrogen osmoprotectant
molecules, such as ciceritol and mannitol in P. tamarugo, would
allow the allocation of nitrogen to support its high photosynthetic
capacity, without compromising its leaf desiccation stress tolerance.