Rice and Sorghum Institute, National Sorghum Improvement Center Sichuan Branch, Sichuan Academy of Agricultural Sciences, Deyang, China.
Chongqing Key Laboratory of Economic Plant Biotechnology, Collaborative Innovation Center of Special Plant Industry in Chongqing, Institute of Special Plants, Chongqing University of Arts and Sciences, Yongchuan, China.
PLoS One. 2020 Sep 17;15(9):e0239075. doi: 10.1371/journal.pone.0239075. eCollection 2020.
Iron (Fe) deficiency is a common challenge in crop production. Screening and research of Fe-efficient cultivars could alleviate plant stress and increase crop yields in Fe-deficient soils. In the present study, we conducted two hydroponic culture experiments with a control (100 μmol/L Fe3+-EDTA) and low Fe treatment (10 μmol/L Fe3+-EDTA) to study the morphological and physiological mechanisms of response to low Fe stress in maize hybrids seedlings. In the first experiment, we investigated 32 major maize hybrids in Southwest China. We found that six of them, including Zhenghong 2 (ZH 2), were Fe-efficient. Fifteen other cultivars, such as Chuandan 418 (CD 418), were Fe-inefficient. In the second experiment, we investigated the Fe-efficient ZH 2 and Fe-inefficient CD 418 cultivars and found that low Fe stress resulted in significant decreases in root volume, root length, number of root tips, root surface area, and root dry weight, and increased root to shoot ratio, average root diameter, and Fe-dissolution ability per mass of roots in both maize cultivars. However, the increase in Fe-dissolution ability per mass of roots in ZH 2 was higher than that in CD 418, whereas for the other measurements, the low Fe stress-induced changes in ZH 2 were less pronounced than in CD 418. Therefore, under low Fe stress, the above-mentioned growth factors in ZH 2 were higher by 54.84%, 121.46%, 107.67%, 83.96%, 140.00%, and 18.16%, respectively, than those in CD 418. In addition, leaf area, chlorophyll content, net photosynthetic rate, soluble protein content, and Catalase (CAT) and Peroxidase (POD) activities in ZH 2 were higher by 274.95%, 113.95%, 223.60%, 56.04%, 17.01% and 21.13% than those in CD 418. Therefore, compared with the Fe-inefficient cultivar (CD 418), the Fe-efficient cultivar (ZH 2) had a more developed root system and greater Fe absorption capacity per mass of roots under low iron stress, promoted the efficient absorption of Fe, maintained a higher photosynthetic area and photosynthetic rate, thereby facilitating the accumulation of photosynthetic products. Moreover, higher soluble protein content and activities of CAT and POD permitted high osmotic regulation and scavenging ability, which is an important physiological mechanism for ZH 2 adaptation to low Fe stress.
缺铁是作物生产中的常见挑战。筛选和研究高效铁品种可以缓解植物在缺铁土壤中的胁迫，提高作物产量。本研究采用水培培养实验，设置对照（100 μmol/L Fe3+-EDTA）和低铁处理（10 μmol/L Fe3+-EDTA），研究玉米杂交种幼苗对低铁胁迫的形态和生理响应机制。在第一个实验中，我们调查了中国西南地区的 32 个主要玉米杂交种，发现其中 6 个品种（包括郑单 2 号）是高效铁品种。其他 15 个品种，如川单 418，是低效铁品种。在第二个实验中，我们调查了高效铁品种郑单 2 号和低效铁品种川单 418，发现低铁胁迫导致两个玉米品种的根体积、根长、根尖数量、根表面积和根干重显著减少，根冠比、平均根直径和每质量根溶解的铁量增加。然而，郑单 2 号每质量根溶解的铁量增加幅度高于川单 418，而其他测量指标中，郑单 2 号受低铁胁迫的变化幅度小于川单 418。因此，在低铁胁迫下，郑单 2 号的上述生长因子分别比川单 418高 54.84%、121.46%、107.67%、83.96%、140.00%和 18.16%。此外，郑单 2 号的叶面积、叶绿素含量、净光合速率、可溶性蛋白含量以及 CAT 和 POD 活性分别比川单 418高 274.95%、113.95%、223.60%、56.04%、17.01%和 21.13%。因此，与低效铁品种（川单 418）相比，高效铁品种（郑单 2 号）在低铁胁迫下具有更发达的根系和更大的每质量根吸收铁的能力，促进了铁的有效吸收，维持了较高的光合面积和光合速率，从而有利于光合产物的积累。此外，较高的可溶性蛋白含量和 CAT 和 POD 活性允许高渗透调节和清除能力，这是郑单 2 适应低铁胁迫的重要生理机制。
