A quick and efficient screen for resistance to iron toxicity in lowland rice
A quick and efficient screen for resistance to iron toxicity in lowland rice
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DOI：
10.1002/jpln.200520540
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发表时间：
2005-12-01
影响因子：
2.5
通讯作者：
Kpongor, DS
中科院分区：
文献类型：
--
作者：
Asch, F;Becker, M;Kpongor, DS
铁 (Fe) 毒性是全球许多低地环境中水稻面临的主要胁迫。由于根部过度吸收 Fe2+ 并将其从顶部转移到叶子中，可能会形成有毒的氧自由基并破坏细胞结构成分，从而损害生理过程。典型的视觉症状是稻叶“古铜色”，导致产量大幅损失，特别是在营养生长早期发生毒性时。该问题最好通过基因型改良（即耐受品种）来解决。然而，发生时间、症状严重程度和产量反应因土壤类型、年份、季节和基因型而异。在一个系统中具有抗性的品种在转移到另一系统时可能会失败。更好地瞄准品种改良需要选择工具来提高我们对过量铁存在下水稻的抗性机制和策略的理解。进行了一项 phytotron 研究，以开发幼苗对铁毒性的抗性筛选，该筛选基于经受不同铁水平（0-3000 mg L-1 Fe 以 Fe(II)SO4 形式提供）的个体植物、胁迫持续时间（暴露 1-5 天）、蒸气压不足（VPD；1.1 和 1.8 kPa）以及幼苗年龄（14 和 28 天）。根据叶子古铜色评分和组织铁浓度评估基因型。在高 VPD 环境中暴露于 2000 mg L-1 Fe 3 天后，对 28 天的幼苗进行评分时，获得了清晰的基因型耐受谱分离。在大多数情况下，叶子古铜色评分与组织铁浓度高度相关（包含者和排除者类型的视觉差异）。这两个参数的组合还确定了组织中耐受高水平铁的基因型，同时仅表现出很少的叶子症状（耐受性包括者）。该筛选允许选择具有低叶子古铜色分数的基因型作为对铁毒性的抵抗力，并且对这些基因型的组织铁浓度的额外分析可以确定在育种计划中使用的一般适应策略。
Iron (Fe) toxicity is a major stress to rice in many lowland environments worldwide. Due to excessive uptake of Fe2+ by the roots and its acropetal translocation into the leaves, toxic oxygen radicals may form and damage cell structural components, thus impairing physiological processes. The typical visual symptom is the "bronzing" of the rice leaves, leading to substantial yield losses, particularly when toxicity occurs during early vegetative growth stages. The problem is best addressed through genotype improvement, i.e., tolerant cultivars. However, the time of occurrence and the severity of symptoms and yield responses vary widely among soil types, years, seasons, and genotypes. Cultivars resistant in one system may fail when transferred to another. Better targeting of varietal improvement requires selection tools improving our understanding of the resistance mechanisms and strategies of rice in the presence of excess iron. A phytotron study was conducted to develop a screen for seedling resistance to Fe toxicity based on individual plants subjected to varying levels of Fe (0-3000 mg L-1 Fe supplied as Fe(II)SO4), stress duration (1-5 d of exposure), vapor-pressure deficit (VPD; 1.1 and 1.8 kPa), and seedling age (14 and 28 d). Genotypes were evaluated based on leaf-bronzing score and tissue Fe concentrations. A clear segregation of the genotypic tolerance spectrum was obtained when scoring 28 d old seedlings after 3 d of exposure to 2000 mg L-1 Fe in a high-VPD environment. In most cases, leaf-bronzing scores were highly correlated with tissue Fe concentration (visual differentiation in includer and excluder types). The combination of these two parameters also identified genotypes tolerating high levels of Fe in the tissue while showing only few leaf symptoms (tolerant includers). The screen allows selecting genotypes with low leaf-bronzing score as resistant to Fe toxicity, and additional analyses of the tissue Fe concentration of those can identify the general adaptation strategy to be utilized in breeding programs.