Africa Rice Center (AfricaRice), 01 BP 4029, Abidjan 01, Cote d'Ivoire.
International Rice Research Institute (IRRI), DAPO Box 7777, Metro Manila, Philippines.
Funct Plant Biol. 2018 Jan;46(1):93-105. doi: 10.1071/FP18129.
Iron (Fe) is a fundamental element involved in various plant metabolic processes. However, when Fe uptake is excessive, it becomes toxic to the plant and disrupts cellular homeostasis. The aim of this study was to determine the physiological and biochemical mechanisms underlying tolerance to Fe toxicity in contrasting rice varieties adapted to African environments. Four varieties (CK801 and Suakoko 8 (tolerant), Supa and IR64 (sensitive)) selected from our previous work were analysed in more detail, and the first part of this study reports morphological, physiological and biochemical responses induced by Fe toxicity in these four varieties. Morphological (shoot length, root length, number of lateral roots), physiological (photosynthesis rate, stomatal conductance, transpiration rate, fluorescence, relative water content and cell membrane stability) and biochemical (tissue Fe, chlorophyll pigments, soluble sugars, protein and starch) traits were measured, as appropriate, on both shoot and root tissues and at different time points during the stress period. Fe toxicity significantly (P≤0.05) reduced growth and metabolism of all the four varieties. Tolerant varieties showed more lateral roots than the sensitive ones, under Fe toxic conditions as well as higher photosynthesis rate, chlorophyll content and cell membrane stability. Strong dilution of Fe concentration in cells was identified, as one of the additional tolerance mechanisms used by CK801, whereas Suakoko 8 mainly used strong mobilisation of carbohydrates at the early stage of the stress period to anticipate metabolite shortage. Traits associated with Fe toxicity tolerance in this study could be specifically targeted in trait-based breeding programs of superior lowland rice varieties tolerant of Fe toxicity.
铁（Fe）是参与各种植物代谢过程的基本元素。然而，当铁吸收过量时，它对植物有毒，破坏细胞内稳态。本研究旨在确定适应非洲环境的不同水稻品种对铁毒性耐受的生理生化机制。从我们之前的工作中选择了四个品种（CK801 和 Suakoko 8（耐受）、Supa 和 IR64（敏感））进行了更详细的分析，本研究的第一部分报告了这四个品种对铁毒性的形态、生理和生化反应。在胁迫期的不同时间点，测量了地上和地下组织的形态（茎长、根长、侧根数）、生理（光合作用速率、气孔导度、蒸腾速率、荧光、相对含水量和细胞膜稳定性）和生化（组织铁、叶绿素色素、可溶性糖、蛋白质和淀粉）特性。铁毒性显著（P≤0.05）降低了所有四个品种的生长和代谢。在铁毒性条件下，耐受品种比敏感品种具有更多的侧根，同时具有更高的光合作用速率、叶绿素含量和细胞膜稳定性。鉴定出一种额外的耐受机制，即 CK801 细胞中铁浓度的强烈稀释，而 Suakoko 8 主要在胁迫期的早期利用碳水化合物的强烈动员来预测代谢物短缺。本研究中与铁毒性耐受相关的性状可以在基于性状的优良低地水稻品种的铁毒性耐受选育计划中作为特定目标。
