Physiological responses of Lepidium meyenii plants to ultraviolet-B radiation challenge

Abstract

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. Electronic supplementary material The online version of this article (10.1186/s12870-019-1755-5) contains supplementary material, which is available to authorized users.

Physiological responses of maca (Lepidium meyenii Walp.) plants to UV radiation in its high-altitude mountain ecosystem

“…However, control plants showed a marked senescence acceleration and generation of new leaves, while plants grown under UV-blocking conditions maintained their green/yellow leaves. Interestingly, similar physiological responses were observed in maca plants subjected to UVB irradiation challenges in growth chamber 15 , suggesting that this coordinated remobilization and relocation of nutrients from old leaves to new leaves and storage organs is an UVB-related response in maca. Further studies must be performed in order to investigate the separate influences of PAR, UVB and UVA in the observed assimilates allocation between above and belowground organs in maca.…”

“…In our previous study 15 we found that maca grown in growth chamber showed differential UVB responses including a coordinated source-sink carbon allocation and a systemic phenotypical plasticity. In this study, we manipulated the solar UV radiation under field conditions in order to understand the influence of UV on physiological responses of maca plants over a complete growing season.…”

“…Even though many studies have been focused on its phytochemical characteristics, less is known regarding the adaptation mechanisms of maca to its particular natural environmental conditions. Our recent study revealed that maca grown in growth chamber showed differential UVB responses including a coordinated source-sink carbon allocation and a systemic phenotypical plasticity 15 . These results prompted us to realistically evaluate the physiological responses of maca to UV in its natural mountain ecosystem, which is much more complex than laboratory-simulated conditions.…”

Environmental effects of stratospheric ozone depletion, UV radiation, and interactions with climate change: UNEP Environmental Effects Assessment Panel, Update 2020

“…Studies of organisms that live at very high elevations are relevant for understanding how species acclimate and adapt to high UV irradiances under extreme environmental conditions. For example, Maca ( Lepidium meyenii ) is a crop from the high Andes in Peru that can quickly recover from stress induced by acute high solar UV radiation [ 162 , 163 ]. Similarly, Chinese tallow trees ( Triadica sebifera ), growing in southern China, accumulate more UV-absorbing flavonoids in their leaves with increasing elevation (100 to 1000 m above sea level) [ 161 ].…”

Comparative analysis of maca (Lepidium meyenii) proteome profiles reveals insights into response mechanisms of herbal plants to high-temperature stress

“…Due to its potential health benefits and valuable medicinal properties, maca has generated great interest in pharmacological and nutritional research and been introduced to many places around the world, which make it an attractive plant for the nutraceutical industry in recent years [ 2 ]. Because it is cultivated at altitudes of up to 3500 to 4500 m, maca possesses robust tolerance to extreme environmental stresses such as cold, strong wind and UV-B exposure [ 1 , 3 ]. Nevertheless, it is extremely sensitive to heat stress [ 1 , 4 ].…”