Department of Botany, Abdul Wali Khan University, Mardan, 23200, Pakistan.
Institute of Biological Sciences Sarhad University, Peshawar, Pakistan.
BMC Plant Biol. 2024 Jul 8;24(1):642. doi: 10.1186/s12870-024-05361-5.
Among the several threats to humanity by anthropogenic activities, contamination of the environment by heavy metals is of great concern. Upon entry into the food chain, these metals cause serious hazards to plants and other organisms including humans. Use of microbes for bioremediation of the soil and stress mitigation in plants are among the preferred strategies to provide an efficient, cost-effective, eco-friendly solution of the problem. The current investigation is an attempt in this direction where fungal strain PH1 was isolated from the rhizosphere of Parthenium hysterophorus which was identified as Aspergillus niger by sequence homology of the ITS 1 and ITS 4 regions of the rRNA. The strain was tested for its effect on growth and biochemical parameters as reflection of its potential to mitigate Pb stress in Zea mays exposed to 100, 200 and 500 µg of Pb/g of soil. In the initial screening, it was revealed that the strain has the ability to tolerate lead stress, solubilize insoluble phosphate and produce plant growth promoting hormones (IAA and SA) and other metabolites like phenolics, flavonoids, sugar, protein and lipids. Under 500 µg of Pb/g of soil, Z. mays exhibited significant growth retardation with a reduction of 31% in root length, 30.5% in shoot length, 57.5% in fresh weight and 45.2% in dry weight as compared to control plants. Inoculation of A. niger to Pb treated plants not only restored root and shoot length, rather promoted it to a level significantly higher than the control plants. Association of the strain modulated the physio-hormonal attributes of maize plants that resulted in their better growth which indicated a state of low stress. Additionally, the strain boosted the antioxidant defence system of the maize there by causing a significant reduction in the ascorbic acid peroxidase (1.5%), catalase (19%) and 1,1-diphenyl-2 picrylhydrazyl (DPPH) radical scavenging activity (33.3%), indicating a lower stress condition as compared to their non-inoculated stressed plants. Based on current evidence, this strain can potentially be used as a biofertilizer for Pb-contaminated sites where it will improve overall plant health with the hope of achieving better biological and agricultural yields.
在人为活动对人类造成的诸多威胁中，重金属对环境的污染引起了极大的关注。这些金属进入食物链后，会对植物和其他生物体（包括人类）造成严重危害。利用微生物进行土壤生物修复和减轻植物压力是提供高效、经济、环保解决方案的首选策略之一。目前的研究就是朝这个方向进行的，从黄菊根际中分离出真菌菌株 PH1，通过核糖体 RNA 的 ITS1 和 ITS4 区域的序列同源性鉴定为黑曲霉。该菌株被测试了其对玉米生长和生化参数的影响，以反映其在玉米暴露于 100、200 和 500μg/g 土壤铅的情况下减轻铅胁迫的潜力。在初步筛选中，发现该菌株具有耐受铅胁迫的能力，可溶解不溶性磷酸盐，并产生植物生长促进激素（IAA 和 SA）和其他代谢物，如酚类、类黄酮、糖、蛋白质和脂质。在 500μg/g 土壤铅下，玉米表现出明显的生长迟缓，与对照植物相比，根长减少 31%，茎长减少 30.5%，鲜重减少 57.5%，干重减少 45.2%。将黑曲霉接种到 Pb 处理过的植物中不仅恢复了根和茎的长度，而且促进了其生长，使其显著高于对照植物。该菌株的共生调节了玉米植株的生理-激素特性，使其生长更好，表明其处于低应激状态。此外，该菌株还增强了玉米的抗氧化防御系统，导致抗坏血酸过氧化物酶（1.5%）、过氧化氢酶（19%）和 1,1-二苯基-2-苦基肼（DPPH）自由基清除活性（33.3%）显著降低，与未接种的应激植物相比，表明其应激条件较低。根据目前的证据，该菌株有可能被用作受 Pb 污染场地的生物肥料，它将改善植物的整体健康状况，希望获得更好的生物和农业产量。
