The potential of SZ01 as a microbial inoculant to promote plant growth and productivity in saline–alkaline environments, with implications for both medicinal and agricultural crop production, is highlighted.
Abstract
Salt-tolerant rhizosphere microorganisms with multiple plant growth–promoting (PGP) traits represent cost-effective biological inoculants for enhancing plant tolerance to abiotic stress.
In this study, a salt-tolerant fungal strain, SZ01, was isolated from the rhizosphere of
Clematis chinensis
using PDA medium supplemented with 1% NaCl and identified as
Trichoderma compactum
based on morphological and molecular analyses. SZ01 tolerated NaCl concentrations up to 9%. Functional characterization revealed that SZ01 exhibited potassium solubilization, nitrogen fixation potential, and siderophore production, although it lacked the ability to solubilize organic or inorganic phosphorus. Pot experiments demonstrated that under salt stress, inoculation with SZ01 spore suspension significantly increased the fresh and dry weights of underground tissues, reduced Malondialdehyde (MDA) accumulation, and enhanced soluble sugar and proline contents compared with non-inoculated controls, indicating effective mitigation of salt-induced physiological damage. Transcriptomic analysis of
C. chinensis
leaves further showed that SZ01 treatment triggered extensive transcriptional reprogramming, particularly through modulation of MAPK and metabolic pathways, thereby optimizing stress-responsive gene expression. Secondary metabolite profiling of SZ01 under salt stress revealed the accumulation of chlorine-containing molecules potentially contributing to plant growth promotion.
These findings highlight the potential of SZ01 as a microbial inoculant to promote plant growth and productivity in saline–alkaline environments, with implications for both medicinal and agricultural crop production.
Salt stress is a prevalent abiotic stress worldwide, which markedly inhibits crop growth and triggers yield losses. In this study, salt-tolerant plant-growth-promoting rhizobacteria of Cerasus humilis—Bacillus pumilus and B. velezensis, which possess nitrogen-fixing, phosphate-solubilizing, and indole-3-acetic acid (IAA) and 1-aminocyclopropane-1-carboxylate (ACC) deaminase-producing traits—were co-inoculated with Sinorhizobium meliloti. The effects of these bacterial combinations on alfalfa (Medicago sativa L.) were systematically evaluated during seed germination and plant growth under salt stress simulated using NaCl, Na2SO4, NaHCO3, and Na2CO3 at varying intensities. The results showed that under salt stress, inoculation significantly increased the seed germination rate by 11.33–41.33%. Pot experiments further revealed that inoculation significantly enhanced symbiotic nitrogen fixation efficiency in alfalfa and effectively maintained K+/Na+ homeostasis (K+ concentration increased by 4.23–125.34%, while Na+ concentration decreased by 7.15–102.09%). Concurrently, inoculation upregulated antioxidant enzyme activities and promoted the accumulation of non-enzymatic antioxidants, thereby significantly reducing reactive oxygen species levels. Moreover, inoculation substantially increased the content of osmoregulatory substances such as proline and soluble protein; proline accumulation surged more than fivefold (39.97–551.05%) compared with the non-inoculated control, effectively alleviating cellular dehydration. Through these multi-pathway regulations mediated by Bacillus sp. and S. meliloti, the inhibitory effect of salt stress on alfalfa growth was significantly mitigated, with dry weight increasing by 45.9–92.4%. Principal component analysis indicated that inoculation with the B. velezensis–S. meliloti microbial combination was the most promising strategy for promoting alfalfa growth and alleviating salt stress. The results provide a theoretical basis for developing microbial fertilizers and establishing alfalfa pastures in saline lands, thereby promoting their sustainable utilization.
Jie Bai, Tuo Yao, Wenbo Xu et al.· Agronomy· 0 citations
Preliminary evidence is provided of the potential of a Streptomyces levis strain as a PGP bacterium under saline conditions and Seed germination efficiency revealed that the 24 hrs culture of isolate H had a significantly greater effect on rice seed germination than the 48 hrs culture.
Anjaiah Gunja, Premsagar Korripally, Vishnuvardhan Reddy Sultanpuram et al.· Journal of Pure and Applied...· 0 citations
Soil salinity is a major abiotic stress that severely restricts crop productivity by disrupting ionic balance, inducing osmotic stress, and promoting oxidative damage. Black gram (Vigna mungo L.), an important pulse crop, is highly sensitive to salinity, resulting in reduced growth, physiological performance, and yield. The present study evaluated the efficacy of a compatible multi-strain HPGPB consortium comprising MKM3 (Halobacillus marinus), MKM4 (Halobacillus halophilus), and MKM11 (Halobacillus halophilus) in enhancing salinity tolerance in two black gram varieties (VBN8 and VBN11) under greenhouse conditions. Plants were subjected to 50 and 100 mM NaCl stress, with and without consortium inoculation, in a completely randomized design. Salinity stress significantly reduced plant growth, photosynthetic pigments, biomass, nutrient uptake, and grain yield, while increasing Na+ accumulation, lipid peroxidation, and osmotic stress markers. Consortium inoculation effectively mitigated these adverse effects by improving plant height, root development, biomass, and grain yield by up to 46 and 38%, respectively, under saline conditions. Consortium-inoculated plants exhibited improved photosynthetic performance, enhanced nutrient uptake and ionic balance, reduced Na+ accumulation and malondialdehyde content, and increased activities of antioxidant enzymes, indicating enhanced salinity tolerance. Among the tested varieties, VBN11 exhibited greater salinity tolerance and a stronger response to consortium inoculation than VBN8. Rhizosphere metagenomic analysis revealed consortium-associated shifts in microbial community structure under saline conditions. Collectively, the results demonstrate that the HPGPB consortium enhances salinity tolerance through coordinated physiological, biochemical, and microbiome-associated mechanisms. These findings highlight the potential of HPGPB consortia as sustainable bioinoculants for improving black gram productivity in salt-affected agroecosystems.
Daniel Raphael, Theivasigamani Parthasarathi· Frontiers in Microbiology· 0 citations
It is shown that endophytic fungi have the potential to enhance plants’ resilience and provide a promising controlled-environment approach to enhance crop productivity in metal- and salt-contaminated soils.
Sobia Khan, Salman Khan, Afshan Afshan et al.· PLoS ONE· 0 citations
This study investigated the potential of the plant growth-promoting rhizobacterium (PGPR) Bacillus velezensis strain MWS28 (MWS28) to enhance abiotic stress tolerance in apple (Malus domestica) plantlets in Korea. Treatments with B. velezensis MWS28 or B. vallismortis EXTN-1 (positive control) by both foliar spraying and dipping methods significantly reduced cold injury symptoms, such as browning and tissue necrosis, compared to untreated controls. MWS28 treatment, especially via foliar spray, suppressed chilling injury by over 85%, outperforming conventional agents like benzothiadiazole (BTH) and streptomycin. Under drought conditions, both MWS28 and EXTN-1 treatments improved relative moisture content (RMC) and minimized leaf wilting throughout the stress period; MWS28-treated plants exhibited the strongest RMC after 15 days of water deprivation. Biochemical analysis showed MWS28-treated plants had significantly elevated activities of antioxidant enzymes (APX, CAT, SOD, and POD) and reduced the malondialdehyde (MDA) levels, indicating enhanced oxidative stress protection and membrane stability. MWS28 treatment also increased endogenous indole-3-acetic acid (IAA) and abscisic acid (ABA) concentrations under stress. Gene expression analysis demonstrated that MWS28 notably upregulated stress-related genes, particularly those involved in antioxidant defense, flavonoid biosynthesis (notably DFR, ANS, and UFGT), and pathogenesis-related (PR5 and PR8) genes in “Fuji” apple leaves using both dipping and foliar spray methods. These results collectively demonstrate that the MWS28 strain confers robust abiotic stress tolerance in apples by enhancing physiological resilience and activating key molecular defenses. This approach offers a promising, sustainable strategy for mitigating climate-related stresses in apple cultivation.
S. Oh, K. Balaraju, D. Yoon et al.· Frontiers in Microbiology· 0 citations
