Abstract
Aluminum (Al) toxicity is one of the major factors that limit the growth and production of crops in acid soils. Highbush blueberry (Vaccinium corymbosum L.) cultivars differing in resistance to Al toxicity regarding root growth and photosynthetic performance were used. In this study, we compared the physiological and metabolic strategies to cope with Al toxicity among the highbush blueberry cultivars [two new ones (Camellia and Cargo) and three established ones (Brigitta (Al-resistant), Star and Duke)]. Aluminum concentration in roots and leaves increased in all cultivars after 24 and 48 h of exposure to Al, but less so in roots of cultivar Camellia and leaves of cultivar Cargo. These two cultivars displayed minor effects of Al exposure in terms of photosynthetic activity in comparison with the established cultivars. Furthermore, Cargo did not vary fluorescence parameters, whereas Camellia exhibited a decrease in effective quantum yield (ΦPSII) and electron transport rate (ETR) and a change in non-photochemical quenching (NPQ) and maximum quantum yield (Fv/Fm) under Al after 48 h. The Al treatment increased total phenols in leaves of Brigitta, Cargo, and Camellia, whereas antioxidant activity increased in Star and Cargo after 48 h. Aluminum exposure decreased malate concentration in roots of all cultivars, but no change was noted in fumarate concentration. The antioxidant activity correlated with photosynthetic performance and the total phenol concentration in the leaves of new cultivars exposed to Al, suggesting enhanced resistance in the short-term experiment. The principal component analysis separated the new from the established cultivars. In conclusion, the new cultivars appear to be more Al-resistant than the established ones, with Star being most Al-sensitive. Regarding the Al-resistance mechanisms of the new cultivars, it is suggested that Camellia could have a root Al-exclusion mechanism under Al toxicity. This mechanism could be explained by low Al concentration in roots, suggesting that this cultivar could exude organic acid, allowing to chelate Al in the rhizosphere. Nonetheless, further researches are needed to confirm this assumption.
Highlights
Acid soils are characterized by nutrient deficiency and toxicity of metals such as manganese (Mn), iron (Fe) and aluminum (Al), with Al toxicity being the main limiting factor for plant growth in acid soils[1]
Due to a lack of differences among time points in treatments without Al, we considered the values at 0 h as the average among the start of the experiment and the respective controls for each time point (24 and 48 h)
In Citrus reshni subjected to Al stress, a decline was reported in CO2 assimilation, non-photochemical quenching (NPQ), the effective quantum yield of PSII (ФPSII), and maximum quantum yield of PSII (Fv/Fm)[16,26]
Summary
Acid soils are characterized by nutrient deficiency and toxicity of metals such as manganese (Mn), iron (Fe) and aluminum (Al), with Al toxicity being the main limiting factor for plant growth in acid soils[1]. Aluminum toxicity to plants includes two www.nature.com/scientificreports/. The Al-related inhibition of growth and injury to root apex cells has been observed in many plants species[11,12,13], including highbush blueberry Vaccinium corymbosum[14]. In highbush blueberry, carbohydrate concentration decreased under Al stress compared with the control[19]. Studies performed in the established highbush blueberry cultivars indicated that short-term Al exposure differentially affects the photochemical features, with Brigitta cultivar showing Al resistance and Bluegold cultivar being Al-sensitive[33]. Despite the importance of these new highbush blueberry cultivars, there is no knowledge of their Al sensitivity/resistance under acidic conditions and Al toxicity. This study aimed to compare the physiological and metabolic strategies of coping with Al toxicity between the new and established highbush blueberry cultivars
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