Metabolic responses of Vaccinium corymbosum L. cultivars to Al3+ toxicity and gypsum amendment

Highbush blueberry (Vaccinium corymbosum L.) is an important crop well adapted to acid soils, but sensitive to Al3+ toxicity. Gypsum amendments are frequently used to reduce Al3+ toxicity in V. corymbosum. However, little is known about the physiological and metabolic responses to gypsum application in plants growing in the presence of Al3+ toxicity. Thus, we evaluated the mechanisms displayed by gypsum application at the metabolite levels in V. corymbosum cultivars growing under Al3+ toxicity. We characterized three cultivars (Brigitta, Legacy, and Bluegold) with different response mechanisms to Al3+ toxicity. Furthermore, four treatments were applied: (i) Acid substrate without Al (Control), (ii) Acid substrate + 1.4 g CaSO4 kg(-1), (iii) Acid substrate + 0.9 g AlCl3 kg(-1) and (iv) Acid substrate + 0.9 g AlCl3 kg(-1) + 1.4 g CaSO4 kg(-1). After ten days of treatment exposition, leaves, and roots were harvested for metabolite profiling analyses. Starch and amino acid concentrations in leaves and roots decreased in all cultivars growing under toxic Al3+ levels. However, gypsum amendment reduced Al concentration in leaves and roots, as well as increased Ca concentrations in leaves, and recovered amino acid and starch levels. In addition, metabolite profiling and multivariate analyses indicated that in roots, gamma-aminobutyric acid (GABA) might be a metabolite related to Al3+ toxicity. Taken together that gypsum amendment ameliorates the Al3+ toxicity, mainly in the cultivar Al-sensitive, Bluegold. The two Al-resistant cultivars (Legacy and Brigitta) showed distinct Al mechanisms (tolerance and exclusion, respectively)