Ribeiro Cleberson, de Marcos Lapaz Allan, de Freitas-Silva Larisse, Ribeiro Karla Veloso Gonçalves, Yoshida Camila Hatsu Pereira, Dal-Bianco Maximiller, Cambraia José
Departamento de Biologia Geral, Universidade Federal de Viçosa, Viçosa, Minas Gerais 36570-900 Brazil.
Departamento de Biologia Vegetal, Universidade Federal de Viçosa, 36570-900 Viçosa, Minas Gerais Brazil.
Physiol Mol Biol Plants. 2022 Dec;28(11-12):2085-2098. doi: 10.1007/s12298-022-01262-9. Epub 2022 Dec 15.
In acidic soil, aluminum (Al) ionizes into trivalent cation and becomes highly toxic to plants. Thus, the objectives of this work were (i) to evaluate the Al concentration and identify sites of Al toxicity and its effect on the structure on rice root tips and (ii) to elucidate the adjustments involved in the activities/contents of enzymes/compounds in the roots against Al. For this, two genotypes with contrasting Al tolerance were used. Our results showed that the root length of the tolerant genotype was not affected after Al exposure. We also observed that both the genotypes used strategies to avoid Al uptake, such as the overlap of P and Al in the tolerant genotype and the presence of border cells in the sensitive genotype, which proved inefficient. In the tolerant genotype, other external Al detoxification mechanisms may have contributed to the lower Al concentration in roots and lower fluorescence of the Al-lumogallion complex. Additionally, both genotypes present the activation of key enzymes to decrease oxidative stress, such as CAT, POX, APX, and DHAR, and a more reducing redox environment, mainly due to the increase in the AA/DHA ratio. However, higher total ascorbate, AA, total glutathione, and GSH contents associated with higher SOD, GPX, and GR activities contributed to the reduction of oxidative stress in the tolerant genotype after Al exposure. Furthermore, there was a strong association between the sensitive genotype to Al concentration, O content, and MDA amount; therefore, these traits can be used as sensitivity indicators in Al studies.
在酸性土壤中，铝（Al）离子化形成三价阳离子，对植物具有高毒性。因此，本研究的目的是：（i）评估铝浓度，确定铝毒性位点及其对水稻根尖结构的影响；（ii）阐明根系中酶/化合物的活性/含量针对铝的调节机制。为此，使用了两种耐铝性不同的基因型。我们的结果表明，耐铝基因型的根长在铝处理后未受影响。我们还观察到，两种基因型都采用了避免铝吸收的策略，例如耐铝基因型中磷和铝的重叠以及敏感基因型中边缘细胞的存在，但这些策略被证明是无效的。在耐铝基因型中，其他外部铝解毒机制可能导致了根中较低的铝浓度和铝-荧光镓络合物较低的荧光强度。此外，两种基因型都表现出关键酶的激活以降低氧化应激，如CAT、POX、APX和DHAR，以及更具还原性的氧化还原环境，这主要是由于AA/DHA比值的增加。然而，较高的总抗坏血酸、AA、总谷胱甘肽和GSH含量以及较高的SOD、GPX和GR活性有助于降低耐铝基因型在铝处理后的氧化应激。此外，对铝浓度敏感的基因型与氧含量和丙二醛含量之间存在很强的相关性；因此，这些性状可作为铝研究中的敏感性指标。
