Water Deficit Induced Physiological and Anatomical Responses of Dioscorea Varieties from Brazil’s Legal Amazon

Research on the physiological and anatomical mechanisms of yam species ( Dioscorea sp.) in response to water deficiency is scarce in the Brazil’s Legal Amazon. Our aim was to analyse in an integrated way the effects of drought stress on the physiological and anatomical traits of endemic and non-endemic Dioscorea species from Brazil’s Amazon at greenhouse conditions. We characterized growth parameters, biomass allocation, leaf gas exchange, chlorophyll fluorescence, water management, and anatomical traits using a factorial design considering plantlets of three Dioscorea varieties (one endemic and two non-endemic plant species) under irrigated and non-irrigated conditions. The highest values of growth parameters (e.g., number of leaves, plant height, dry biomass) were found on pots where D. alata L. var. purpurea was cultivated under irrigated conditions, whereas for aboveground biomass allocation, and root biomass allocation the highest values were found on pots where D. alata var. white was cultivated. For gas exchange we found the highest values in the endemic plant species D. trifida L.f. Impacts of water deficit were also observed on the anatomical traits. The results of this study highlight the importance to consider drought stress modulating Dioscorea species’ traits. Our findings suggest that (1) the non-endemic species proved to be more tolerant to drought due to better water management, while the endemic species managed to maintain photosynthesis using mechanism of biomass allocation and leaf gas exchange, and (2) by altering plant traits, endemic and non-endemic plant species may create different response by changing their morphology, physiology, and/or anatomy to improve their own tolerance to drought stress.