Lead (Pb) is one of the major environmental heavy metal pollutants, known as being neither essential nor beneficial for any living organisms, and which is detrimental to plant fitness, growth, and productivity, as well as human health. This study investigated the changes in the morphological, physiological, and biochemical properties of rice cultivars exposed to lead (Pb). Therefore, soil was contaminated with a solution containing 0.6 mM or 1.2 mM Pb four weeks prior to transplanting. Then, 4-week-old rice seedlings of Tunnae, Ilmi, Yasmen, Mashkab, and Amber Barka were transplanted into the contaminated soil and grown until maturity. The results showed that a high concentration of lead (1.2 mM) induced significant reduction in the plant height, number of tillers, number of panicles per plant, and the number of spikelets per panicle in Pb-sensitive rice cultivars, while in Pb-tolerant cultivars, a balanced growth of plants and non-significant change in the major yield components were recorded. However, all rice cultivars showed a reduced biomass dry weight. Under the same conditions, we observed a differential enzymatic antioxidant activity, with catalase (CAT) and peroxidase (POD) being the most active. In addition, the proline accumulation and sucrose content increased concomitant with an increase in the Pb concentration, while the total protein and chlorophyll contents significantly decreased. Of all the soluble sugars analyzed, sucrose was the most abundant in response to Pb treatment. Interestingly, the rice cultivars Tunnae and Mashkab exhibited a high degree of tolerance towards Pb stress, with a balanced plant height, number of tillers, number of panicles, and number of spikelets per plant. Therefore, all results collectively suggest that the tolerance to Pb-induced oxidative stress observed in Tunnae and Mashkab could be a result of a synergetic action of both enzymatic and non-enzymatic antioxidant systems, leading to a balanced reduction–oxidation status in rice.

中文翻译：

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铅（Pb）诱导的氧化胁迫改变水稻（Oryzasativa L.）的形态和生理生化特性

铅（Pb）是主要的环境重金属污染物之一，对任何活生物体都不是必需或无益，对植物的健康，生长和生产力以及人类健康都是有害的。这项研究调查了铅（Pb）暴露的水稻品种的形态，生理和生化特性的变化。因此，在移植前四周，土壤被含有0.6 mM或1.2 mM Pb的溶液污染。然后，将4周龄的Tunnae，Ilmi，Yasmen，Mashkab和Amber Barka的水稻幼苗移植到受污染的土壤中，直到成熟。结果表明，高浓度的铅（1.2 mM）导致株高，分till数，单株穗数显着降低，在对铅敏感的水稻品种中，每穗的小穗数，而在对铅敏感的水稻品种中，记录到植物的平衡生长和主要产量成分的无明显变化。但是，所有水稻品种均显示出降低的生物质干重。在相同条件下，我们观察到了不同的酶抗氧化活性，其中过氧化氢酶（CAT）和过氧化物酶（POD）的活性最高。此外，脯氨酸的积累和蔗糖含量随Pb浓度的增加而增加，而总蛋白和叶绿素的含量则显着下降。在分析的所有可溶性糖中，蔗糖对铅处理的响应最丰富。有趣的是，水稻品种Tunnae和Mashkab表现出对Pb胁迫的高度耐受性，并且株高平衡，每棵植物的分till数，穗数和小穗数。因此，所有结果共同表明，在Tunnae和Mashkab中观察到的对Pb诱导的氧化胁迫的耐受性可能是酶和非酶抗氧化剂系统协同作用的结果，从而导致水稻平衡的还原-氧化状态。