Department of Biology, Faculty of Science, Silpakorn University, Nakhon Pathom, 73000, Thailand.
National Center for Genetic Engineering and Biotechnology (BIOTEC), National Science and Technology Development Agency (NSTDA), 113 Paholyothin Rd, Khlong Nueng, Khlong Luang, Pathum Thani, 12120, Thailand.
Environ Geochem Health. 2023 Jan;45(1):187-197. doi: 10.1007/s10653-022-01291-z. Epub 2022 May 30.
Aluminum (Al) contamination in acidic soil is a major problem in paddy field, causing grain yield loss, especially in central plains of Thailand. The objective of this study was to assess Al content in the root tissues, its translocation to the leaves, and Al toxicity in three genotypes of rice, RD35 (local acidic-tolerant), Azucena (positive-check Al-tolerant), and IR64 (high yielding) under 0 (control) or 1 mM AlCl (Al toxicity) at pH 4.5. Al content in the root tissues of rice cv. RD35 under 1 mM AlCl was peaked at 4.18 mg g DW and significantly translocated to leaf tissues (0.35 mg g DW), leading to reduced leaf greenness (SPAD) (by 44.9% over the control) and declined net photosynthetic rate (P) (by 54.5% over the control). In contrast, Al level in cvs. Azucena and IR64 was restricted in the roots (2.12 mg g DW) with low amount of translocation in the leaf tissues (0.26 mg g DW), resulting in maintained values of SPAD and P. In cv. RD35, root and shoot traits including root length, root fresh weight, shoot height, shoot fresh weight, and shoot dry weight in 1 mM Al treatment were significantly dropped by > 35% over the control, whereas these parameters in cvs. Azucena and IR64 were retained. Based on the results, RD35 rice genotype was identified as Al sensitive as it demonstrated Al toxicity in both aboveground and belowground parts, whereas Azucena and IR64 were found tolerant to 1 mM Al as they demonstrated storage of Al in the root tissues to reduce toxicity in the leaf tissues. The study suggests that root traits, shoot attributes, chlorophyll degradation, and photosynthetic reduction can be successfully employed for the screening of Al-tolerant genotypes in rice breeding programs.
在酸性土壤中，铝（Al）污染是稻田的一个主要问题，特别是在泰国中部平原，会导致粮食减产。本研究的目的是评估三种水稻基因型（RD35，本地耐酸；Azucena，耐 Al 阳性对照；IR64，高产量）在 pH 值为 4.5 时，在 0（对照）或 1 mM AlCl（Al 毒性）下，根组织中 Al 的含量、向叶片的迁移以及 Al 毒性。在 1 mM AlCl 下，RD35 水稻品种的根组织中 Al 含量达到峰值 4.18 mg g DW，并显著向叶片组织迁移（0.35 mg g DW），导致叶片绿色度（SPAD）降低（比对照低 44.9%）和净光合速率（P）下降（比对照低 54.5%）。相比之下，Azucena 和 IR64 品种的 Al 水平限制在根部（2.12 mg g DW），向叶片组织的迁移量较低（0.26 mg g DW），因此 SPAD 和 P 保持不变。在 RD35 品种中，根和地上部分的特征，包括根长、根鲜重、株高、株鲜重和株干重，在 1 mM Al 处理下比对照分别下降了超过 35%，而 Azucena 和 IR64 品种的这些参数则保持不变。基于这些结果，RD35 水稻基因型被鉴定为对 Al 敏感，因为它在地上和地下部分都表现出 Al 毒性，而 Azucena 和 IR64 则被发现对 1 mM Al 耐受，因为它们在根组织中储存 Al 以减少叶片组织中的毒性。该研究表明，根特性、地上部分属性、叶绿素降解和光合作用减少可以成功地用于水稻育种计划中耐 Al 基因型的筛选。
