BACKGROUND: Ultraviolet-B (UV-B) radiation can affect several aspects ranging from plant growth to metabolic regulation. Maca is a Brassicaceae crop native to the Andes growing in above 3500 m of altitude. Although maca has been the focus mainly due to its nutraceutical properties, it remains unknown how maca plants tolerate to harsh environments, such as strong UV-B. Here, we present the first study that reports the physiological responses of maca plants to counteract and recover to repeated acute UV-B irradiation. RESULTS: In detail, plants were daily exposed to acute UV-B irradiation followed by a recovery period under controlled conditions. The results showed that repeated acute UV-B exposures reduced biomass and photosynthetic parameters, with gradual senescence induction in exposed leaves, reduction of young leaves expansion and root growth inhibition. Negative correlation between increased UV-B and recovery was observed, with marked production of new biomass in plants treated one week or more. CONCLUSIONS: A differential UV-B response was observed: stress response was mainly controlled by a coordinated source-sink carbon allocation, while acclimation process may require UV-B-specific systemic defense response reflected on the phenotypic plasticity of maca plants. Moreover, these differential UV-B responses were also suggested by multifactorial analysis based on biometric and physiological data.

Center for Translational Medicine St Anne's University Hospital 62500 Brno Czech Republic

Department of Agriculture Food and Environment University of Pisa Via del Borghetto 80 56124 Pisa Italy

Department of Agriculture Food and Environment University of Pisa Via del Borghetto 80 56124 Pisa Italy Interdepartmental Research Center Nutraceuticals and Food for Health University of Pisa Via del Borghetto 80 56124 Pisa Italy

Institute of Research on Terrestrial Ecosystems National Research Council Via Moruzzi 1 56124 Pisa Italy

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