Amity Institute of Organic Agriculture, Amity University Uttar Pradesh, Sector 125, Noida, Uttar Pradesh 201313, India.
I-2 block, AIOA, Amity University Uttar Pradesh, Sector 125, Noida, Uttar Pradesh 201313, India.
J Biotechnol. 2020 Dec 20;324:183-197. doi: 10.1016/j.jbiotec.2020.10.024. Epub 2020 Oct 23.
ACC deaminase producing Plant growth promoting rhizobacteria (PGPR) offers a great promise for ameliorating the negative impacts of salinity stress manifested on plants. In this context, 28 rhizospheric bacteria associated with ACC deaminase potential (198-1069 nmol α-ketobutyrate mg protein h) were isolated from 5 different islands of Lakshadweep, union territory, India- Agatti, Kavaratti, Bangaram, Kadmat, and Thinnakara islands using DF-minimal medium. The diversity of cultivable ACC deaminase producing bacteria was analysed by PCR-RFLP (Restriction Fragment Length Polymorphism) method using three endonucleases AluI, MspI and HaeIII which led to the grouping of these isolates into six clusters at 80 % similarity index. Subsequently, isolates were functionally characterized for various PGP traits such that indole-3-acetic acid (IAA) production (∼10-80 μg mL); 16 isolates had phosphate solubilizing potential ranging from ∼19 to 88 P mg L ; siderophore and ammonia production abilities were observed in 5 and 24 isolates, respectively while two strains tolerated up to 8% NaCl. Phylogenetic analysis of 16S rRNA gene sequences of representative strain from each cluster revealed that twenty-eight ACC deaminase producing PGPR belong to eight distinct genera: Pseudomonas, Bacillus, Azospirillum, Azotobacter, Escherichia, Paenibacillus, Burkholderia, and Klebsiella. Two isolates, CO1 (Pseudomonas putida) and CO8 (Bacillus paramycoides) were evaluated for plant growth promoting effects on French bean (Phaseolus vulgaris) under salinity (100 mM NaCl) stress. Both the selected isolates in consortium form significantly increased the root length, shoot length, root fresh and dry weight, shoot fresh and dry weight of French bean seedlings exposed to salinity stress, compared to non-inoculated control plants. The co-inoculation with selected strains CO1 and CO8 has significantly improved chlorophyll concentration, relative water content, membrane stability index, gas exchange parameters including net photosynthesis rate (P), stomatal conductance (g), transpiration rate (E) and water use efficiency of French bean plants by ∼100 %, ∼85 %, ∼40 %, ∼198 %, ∼80 %, ∼70 % and ∼75 %, respectively under saline conditions in comparison with non-inoculated plants. Moreover, the consortium treated French bean plants showed lower levels of stress-induced ethylene by 38 %, electrolyte leakage and Malondialdehyde (MDA) content by ∼15 % under salt stress compared to non-inoculated ones. This study unveiled the potential of halotolerant strains, Pseudomonas putida and Bacillus paramycoides as French bean biofertilizers in mitigating the adverse effects of salinity in plant growth in sustainable agriculture.
具有 ACC 脱氨酶的植物促生根际细菌（PGPR）为缓解盐胁迫对植物的负面影响提供了巨大的希望。在这种情况下，从印度拉克沙迪维群岛的 5 个不同岛屿（阿加蒂、卡瓦拉蒂、班加罗尔、卡德马和蒂纳卡拉岛）的根际中分离出 28 株与 ACC 脱氨酶潜能相关的（198-1069 nmol α-酮丁酸 mg 蛋白 h）的根际细菌，使用 DF-最小培养基。通过使用三种内切酶 AluI、MspI 和 HaeIII 的 PCR-RFLP（限制性片段长度多态性）方法分析了可培养 ACC 脱氨酶产生细菌的多样性，这导致这些分离株在 80%相似性指数下分为 6 个聚类。随后，对分离株进行了各种 PGPR 特性的功能表征，结果表明，吲哚-3-乙酸（IAA）的产生（约 10-80 μg mL）；16 个分离株具有溶磷能力，范围约为 19 到 88 P mg L；铁载体和氨产生能力分别在 5 和 24 个分离株中观察到，而两个菌株可耐受高达 8%的 NaCl。对每个聚类的代表性菌株的 16S rRNA 基因序列进行系统发育分析表明，28 株 ACC 脱氨酶产生的 PGPR 属于 8 个不同的属：假单胞菌、芽孢杆菌、固氮菌、固氮螺菌、大肠杆菌、类芽孢杆菌、伯克霍尔德菌和克雷伯氏菌。两种分离株，CO1（恶臭假单胞菌）和 CO8（副地衣芽孢杆菌），在盐度（100 mM NaCl）胁迫下对菜豆的生长促进作用进行了评价。与未接种对照植物相比，在盐胁迫下，所选分离株以共生形式显著增加了菜豆幼苗的根长、茎长、根鲜重和干重、茎鲜重和干重。与未接种的植物相比，所选菌株 CO1 和 CO8 的共接种显著提高了菜豆植株的叶绿素浓度、相对水含量、膜稳定性指数、净光合速率（P）、气孔导度（g）、蒸腾速率（E）和水分利用效率等气体交换参数，分别提高了约 100%、85%、40%、198%、80%、70%和 75%。此外，与未接种的植物相比，共生处理的菜豆植株在盐胁迫下，应激诱导的乙烯水平降低了 38%，电解质泄漏和丙二醛（MDA）含量降低了约 15%。这项研究揭示了耐盐菌株恶臭假单胞菌和副地衣芽孢杆菌作为菜豆生物肥料的潜力，可在可持续农业中缓解盐胁迫对植物生长的不利影响。
