Lata Debebe Landina, Abdie Oumer, Rezene Yayis
Department of Biotechnology, College of Natural and Computational Science, Wolkite University, Wolkite, Ethiopia.
Molecular Biotech Laboratory, Southern Agricultural Research Institute, Hawassa, Ethiopia.
Heliyon. 2024 Oct 22;10(21):e39702. doi: 10.1016/j.heliyon.2024.e39702. eCollection 2024 Nov 15.
Indole-3-acetic acid (IAA), a crucial plant hormone, regulates diverse physiological processes. This study aimed to isolate and characterize IAA-producing bacteria from the chickpea ( L.) rhizosphere and evaluate their effects on plant growth. From 54 rhizosphere samples, 118 bacteria (designated as GAC) were isolated and screened for IAA production using a Salkowski colorimetric assay, and Bergey's manual was used for biochemical identification. Isolates were grown under various conditions and screened for their growth promotion traits. A PCR investigation was performed for IAA and nitrogen-fixing genes, and evaluated for greenhouse conditions. Among them, 27 isolates produced IAA, with eight high producers selected. Morphological and biochemical identification classified the six isolates as and the other two as . Optimal conditions for IAA production were observed at 500 μg/ml tryptophan, 35 °C, and pH 7.0. A 48-h incubation was ideal for IAA production, except for GAC-34 and GAC-73, which required 72 h. All the isolates achieved optimal IAA levels with tryptone and sucrose as nitrogen and carbon sources, respectively. Moreover, all isolates showed nitrogen fixation ability, and the six isolates exhibited phosphate solubilization. PCR confirmed the amplification of (300 bp), (360 bp), and (1170 bp) genes. Greenhouse experiments demonstrated that eight selected isolates significantly enhanced chickpea growth parameters (p < 0.001). These findings suggest that these IAA-producing bacteria have the potential to be used as biofertilizers to improve crop productivity, although further molecular identification and field studies are required.
吲哚-3-乙酸（IAA）是一种关键的植物激素，可调节多种生理过程。本研究旨在从鹰嘴豆根际分离并鉴定产IAA的细菌，并评估它们对植物生长的影响。从54个根际样本中分离出118株细菌（命名为GAC），使用索氏比色法筛选其IAA产量，并依据《伯杰氏手册》进行生化鉴定。将分离菌株在不同条件下培养，并筛选其促生长特性。对IAA和固氮基因进行PCR检测，并在温室条件下进行评估。其中，27株分离菌产生IAA，挑选出8株高产菌。形态学和生化鉴定将6株分离菌归类为 ，另外2株归类为 。IAA产生的最佳条件为500μg/ml色氨酸浓度、35℃和pH 7.0。除GAC-34和GAC-73需要72小时外，48小时培养是IAA产生的理想时间。所有分离菌分别以胰蛋白胨和蔗糖作为氮源和碳源，达到了最佳IAA水平。此外，所有分离菌均表现出固氮能力，6株分离菌表现出解磷能力。PCR证实了 （300bp）、 （360bp）和 （1170bp）基因的扩增。温室实验表明，8株挑选出的分离菌显著提高了鹰嘴豆的生长参数（p<0.001）。这些发现表明，尽管需要进一步的分子鉴定和田间研究，但这些产IAA的细菌有潜力用作生物肥料来提高作物产量。
