Acid soils with elevated aluminum (Al) saturations are worldwide distributed and harm the crop production in most of the tropical and subtropical regions. The initial and most dramatic symptoms of Al toxicity are changes on the external morphology and inhibition of elongation of roots. These changes have served as a marker for level of Al toxicity and the ability of plants tolerate this metal. Therefore, the goal of this study was to evaluate the Al effects on the growth root and the external morphology of root tips in two rice genotypes: Fernandes (CNA-1158) and Maravilha (CNA-6843-1), tolerant and sensitive to Al, respectively. The genotypes were treated with 0 and 1 mM of Al in Clark’s solution for different times (3, 6 and 9 days). The contents and the distribution of Al in root tips, as well as its morphology, were analyzed. After Al exposure, the content of this metal was higher in Al-sensitive genotype leading to inhibition of root length and decrease in root dry matter production, after the sixth day of treatment. Additionally, Al accumulation in the root tips (0–3 mm) of both genotypes was detected mainly in root cap cells. We also observed damage in the external micromorphology of the root tips, especially in the Al-sensitive Maravilha genotype. Al accumulation in root tips of this genotype induced cellular disorganization in the root cap cells, resulting in the peeling of the superficial layers. Overall, our findings evidenced the higher tolerance of one of genotypes (genotype Fernandes) to Al.

中文翻译：

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铝对水稻根尖外部形态的影响

铝 (Al) 饱和度升高的酸性土壤分布于世界各地，并危害大部分热带和亚热带地区的作物生产。铝中毒的最初和最显着的症状是外部形态的变化和根伸长的抑制。这些变化已作为铝毒性水平和植物耐受这种金属的能力的标志。因此，本研究的目的是评估铝对两种水稻基因型生长根和根尖外部形态的影响：Fernandes (CNA-1158) 和 Maravilha (CNA-6843-1)，对铝耐受和敏感， 分别。基因型在克拉克溶液中用 0 和 1 mM Al 处理不同时间（3、6 和 9 天）。分析了铝在根尖中的含量和分布，以及形态。铝曝光后，在处理第 6 天后，这种金属在铝敏感基因型中的含量较高，导致根长度受到抑制，根干物质产量减少。此外，主要在根冠细胞中检测到两种基因型根尖（0-3 mm）中的铝积累。我们还观察到根尖外部微形态的损伤，尤其是对铝敏感的 Maravilha 基因型。该基因型根尖中铝的积累诱导根冠细胞中的细胞解体，导致表层剥落。总的来说，我们的研究结果证明了一种基因型（基因型 Fernandes）对铝的耐受性更高。此外，主要在根冠细胞中检测到两种基因型根尖（0-3 mm）中的铝积累。我们还观察到根尖外部微形态的损伤，尤其是对铝敏感的 Maravilha 基因型。该基因型根尖中铝的积累诱导根冠细胞中的细胞解体，导致表层剥落。总的来说，我们的研究结果证明了一种基因型（基因型 Fernandes）对铝的耐受性更高。此外，主要在根冠细胞中检测到两种基因型根尖（0-3 mm）中的铝积累。我们还观察到根尖外部微形态的损伤，尤其是对铝敏感的 Maravilha 基因型。该基因型根尖中铝的积累诱导根冠细胞中的细胞解体，导致表层剥落。总的来说，我们的研究结果证明了一种基因型（基因型 Fernandes）对铝的耐受性更高。导致表层剥落。总的来说，我们的研究结果证明了一种基因型（基因型 Fernandes）对铝的耐受性更高。导致表层剥落。总的来说，我们的研究结果证明了一种基因型（基因型 Fernandes）对铝的耐受性更高。