Abstract Aluminum (Al) is an important factor that limits plant growth under acidic soil conditions. However, several plant species developed distinct mechanisms that limit the damage caused by high Al concentrations. In highbush blueberry (Vaccinium corymbosum), the Al resistance mechanisms are not fully understood. This study was designed to evaluate the effect of Al toxicity on roots and leaves of highbush blueberry genotypes with contrasting Al resistance [Star (Al-sensitive) and Camellia and Cargo (Al-resistant)] and identify the main molecular and physiological strategies underpinning adaptive Al stress responses in nutrient solution. After 48 h of Al treatment, the reduced form of ascorbate (ASC) was higher in roots, but unchanged in leaves of Cargo and Camellia genotypes compared to the control. We also observed decreased root exudation of oxalate in the Al-treated sensitive cultivar Star throughout the treatment period. However, in the resistant cultivar (Camellia), the exudation of oxalate increased 2.4- and 2.8-fold at 24 and 48 h, respectively. Al treatment differentially affected the enzyme activity and gene expression of the tricarboxylic acid (TCA) cycle enzymes. NAD-dependent malate dehydrogenase (NAD-MDH) expression in roots of cultivar Cargo was reduced at 24 h and increased at 48 h, whereas in leaves the expression was higher at 24 h and decreased at 48 h compared to the control. Citrate synthase (CS) activity in Al-resistant Cargo roots diminished at 24 h, increasing afterwards, without variation in the CS gene expression, compared with the initial time point (t = 0). In Al-resistant Camellia roots, the gene expression and the activity of CS decreased during Al exposure. NADP-dependent malate dehydrogenase (NADP-MDH) activity showed increased activity and gene expression at 24 h, in the leaves of cultivar Cargo, whereas in roots the gene expression decreased, but the activation state of NADP-MDH increased. The expression of genes encoding TCA cycle enzymes did not differ significantly in the Al-sensitive cultivar Star during Al exposure. In conclusion, the exudation of organic acid anions, particularly oxalate, plays an important role in Al resistance of highbush blueberry genotypes whilst elevated levels of ASC in roots, also contribute to the Al-resistance mechanisms exhibited by genotypes Camellia and Cargo.

中文翻译：

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高丛蓝莓（Vaccinium corymbosum L.）品种的代谢组学分析揭示了对铝毒性的抗性机制

摘要 铝（Al）是酸性土壤条件下限制植物生长的重要因素。然而，一些植物物种发展出不同的机制来限制高铝浓度造成的损害。在高丛蓝莓（Vaccinium corymbosum）中，铝抗性机制尚不完全清楚。本研究旨在评估 Al 毒性对具有对比 Al 抗性 [Star（Al 敏感）和 Camellia and Cargo（Al 抗性）] 的高丛蓝莓基因型根和叶的影响，并确定支持适应性的主要分子和生理策略。营养液中的铝胁迫反应。铝处理 48 小时后，与对照相比，Cargo 和 Camellia 基因型根中抗坏血酸 (ASC) 的还原形式较高，但叶中没有变化。我们还观察到在整个处理期间，铝处理的敏感品种 Star 中草酸盐的根系分泌物减少。然而，在抗性品种（山茶花）中，草酸盐的渗出量分别在 24 和 48 小时增加了 2.4 倍和 2.8 倍。铝处理对三羧酸 (TCA) 循环酶的酶活性和基因表达有不同的影响。与对照相比，栽培品种 Cargo 根中 NAD 依赖性苹果酸脱氢酶 (NAD-MDH) 的表达在 24 小时时降低并在 48 小时时增加，而在叶子中的表达在 24 小时时更高，在 48 小时时降低。与初始时间点 (t = 0) 相比，Al 抗性 Cargo 根中的柠檬酸合酶 (CS) 活性在 24 小时时减弱，之后增加，CS 基因表达没有变化。在耐铝的山茶根中，在铝暴露期间，CS 的基因表达和活性降低。NADP 依赖性苹果酸脱氢酶 (NADP-MDH) 活性在 24 小时时在栽培品种 Cargo 的叶子中显示出增加的活性和基因表达，而在根中，基因表达降低，但 NADP-MDH 的激活状态增加。在铝暴露期间，铝敏感品种 Star 中编码 TCA 循环酶的基因的表达没有显着差异。总之，有机酸阴离子的渗出，特别是草酸盐，在高丛蓝莓基因型的铝抗性中起重要作用，而根中 ASC 水平升高，也有助于基因型山茶和货物表现出的铝抗性机制。NADP 依赖性苹果酸脱氢酶 (NADP-MDH) 活性在 24 小时时在栽培品种 Cargo 的叶子中显示出增加的活性和基因表达，而在根中，基因表达降低，但 NADP-MDH 的激活状态增加。在铝暴露期间，铝敏感品种 Star 中编码 TCA 循环酶的基因的表达没有显着差异。总之，有机酸阴离子的渗出，特别是草酸盐，在高丛蓝莓基因型的铝抗性中起重要作用，而根中 ASC 水平升高，也有助于基因型山茶和货物表现出的铝抗性机制。NADP 依赖性苹果酸脱氢酶 (NADP-MDH) 活性在 24 小时时在栽培品种 Cargo 的叶子中显示出增加的活性和基因表达，而在根中，基因表达降低，但 NADP-MDH 的激活状态增加。在铝暴露期间，铝敏感品种 Star 中编码 TCA 循环酶的基因的表达没有显着差异。总之，有机酸阴离子的渗出，特别是草酸盐，在高丛蓝莓基因型的铝抗性中起重要作用，而根中 ASC 水平升高，也有助于基因型山茶花和货物表现出的铝抗性机制。在铝暴露期间，铝敏感品种 Star 中编码 TCA 循环酶的基因的表达没有显着差异。总之，有机酸阴离子的渗出，特别是草酸盐，在高丛蓝莓基因型的铝抗性中起重要作用，而根中 ASC 水平升高，也有助于基因型山茶和货物表现出的铝抗性机制。在铝暴露期间，铝敏感品种 Star 中编码 TCA 循环酶的基因的表达没有显着差异。总之，有机酸阴离子的渗出，特别是草酸盐，在高丛蓝莓基因型的铝抗性中起重要作用，而根中 ASC 水平升高，也有助于基因型山茶和货物表现出的铝抗性机制。