The effect of salt-tolerant antagonistic bacteria from tomato rhizosphere on plant growth promotion and damping-off disease suppression under salt-stress conditions

Plant growth-promoting rhizobacteria can effectively reduce the severity of different abiotic stresses like water stress, temperature stress, salt stress, etc. on plant growth and development. The study aimed at isolating salt-tolerant rhizobacteria followed by their morphological, biochemical and plant growth promotion traits evaluation. Sixteen root samples of nine different plant species were collected from two locations of Patuakhali, a coastal southern district of Bangladesh. Thirty rhizobacteria were isolated, fifteen from each location, to assess their halotolerance and plant growth promoting potential. The isolated rhizobacteria were subjected to morphological (viz. shape, colour and elevation), biochemical (viz. Gram reaction, catalase test and HCN production) and growth-promoting traits [viz. phosphate solubilizing ability, salt tolerance, indole-3-acetic acid (IAA) production, and N2-fixation] characterization. Twenty-eight isolates were Gram positive, 27 were catalase positive, and nine showed varying degrees of phosphate solubilization on National Botanical Research Institute of Phosphate (NBRIP) medium. Isolate PWB5 showed the highest phosphate solubilizing index (PSI = 3.83±0.098) on the 6th day. To screen salt-tolerant rhizobacteria, the isolates were cultured in NBA media containing different (0%, 2.5%, 5%, 7.5%, 10%, 12%, 15%) NaCl concentrations. Isolate PWB12 and PWB13 grew at 15% NaCl concentration. Eleven isolates exhibited IAA producing ability on Winogradsky medium amended with L-tryptophan among which four (PMB13, PMB14, PMB15 and PWB6) were strong IAA producers. Twenty-seven isolates were potential N2-fixer and among them, 20 were highly efficient, but none of the isolates was HCN producer. The rhizobacteria isolated in the current research work showed some potential plant growth-promoting traits which seem applicable for crop production, especially, under salt stress condition.

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Biological Control of Chili Damping-Off Disease, Caused by Pythium myriotylum

Frontiers in Microbiology ◽

10.3389/fmicb.2021.587431 ◽

2021 ◽

Vol 12 ◽

Author(s):

Sajjad Hyder ◽

Amjad Shahzad Gondal ◽

Zarrin Fatima Rizvi ◽

Rashida Atiq ◽

Muhammad Irtaza Sajjad Haider ◽

...

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Disease Suppression ◽

Root Weight ◽

Dual Culture ◽

Bacterial Isolates ◽

Damping Off ◽

Pythium Myriotylum ◽

Pgp Traits

Pythium myriotylum is a notorious soil-borne oomycete that causes post-emergence damping-off in chili pepper. Of various disease management strategies, utilization of plant growth promoting rhizobacteria (PGPR) in disease suppression and plant growth promotion is an interesting strategy. The present study was performed to isolate and characterize PGPR indigenous to the chili rhizosphere in Pakistan, and to test the potential to suppress the damping-off and plant growth promotion in chili. Out of a total of 28 antagonists, eight bacterial isolates (4a2, JHL-8, JHL-12, 1C2, RH-24, 1D, 5C, and RH-87) significantly suppressed the colony growth of P. myriotylum in a dual culture experiment. All the tested bacterial isolates were characterized for biochemical attributes, and 16S rRNA sequence based phylogenetic analysis identified these isolates as Flavobacterium spp., Bacillus megaterium, Pseudomonas putida, Bacillus cereus, and Pseudomonas libanensis. All the tested bacterial isolates showed positive test results for ammonia production, starch hydrolase (except 4a2), and hydrogen cyanide production (except 4a2 and 1D). All the tested antagonists produced indole-3-acetic acid (13.4–39.0 μg mL–1), solubilized inorganic phosphate (75–103 μg mL–1), and produced siderophores (17.1–23.7%) in vitro. All the tested bacterial isolates showed varying levels of susceptibility and resistance response against different antibiotics and all these bacterial isolates were found to be non-pathogenic to chili seeds and notably enhanced percentage seed germination, plumule, redical length, and vigor index over un-inoculated control. Additionally, under pathogen pressure, bacterization increased the defense related enzymes such as Peroxidase (PO), polyphenol oxidase (PPO), and phenylalanine ammonia-lyase (PAL) activates. Moreover, the treatment of chili seeds with these bacterial isolates significantly suppressed the damping-off caused by P. myriotylum and improved PGP traits compared to the control. In addition, a positive correlation was noticed between shoot, root length, and dry shoot and root weight, and there was a negative correlation between dry shoot, root weight, and seedling percentage mortality. These results showed that native PGPR possesses multiple traits beneficial to the chili plants and can be used to develop eco-friendly and effective seed treatment formulation as an alternative to synthetic chemical fungicides.

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Osmoadaptation and plant growth promotion by salt tolerant bacteria under salt stress

African Journal of Microbiology Research ◽

10.5897/ajmr11.736 ◽

2011 ◽

Vol 5 (21) ◽

Cited By ~ 1

Author(s):

Aisha Waheed Qurashi

Keyword(s):

Salt Stress ◽

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Salt Tolerant

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Plant Growth Promotion by ACC Deaminase-Producing Bacilli Under Salt Stress Conditions

Bacilli in Climate Resilient Agriculture and Bioprospecting - Bacilli and Agrobiotechnology: Phytostimulation and Biocontrol ◽

10.1007/978-3-030-15175-1_5 ◽

2019 ◽

pp. 81-95 ◽

Cited By ~ 2

Author(s):

Gustavo Santoyo ◽

Adrian Equihua ◽

Aurora Flores ◽

Edgardo Sepulveda ◽

Eduardo Valencia-Cantero ◽

...

Keyword(s):

Salt Stress ◽

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Acc Deaminase ◽

Stress Conditions

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Role of Halotolerant Microbes in Plant Growth Promotion Under Salt Stress Conditions

Saline Soil-based Agriculture by Halotolerant Microorganisms ◽

10.1007/978-981-13-8335-9_10 ◽

2019 ◽

pp. 209-253 ◽

Cited By ~ 2

Author(s):

Zahir Ahmad Zahir ◽

Sajid Mahmood Nadeem ◽

Muhammad Yahya Khan ◽

Rana Binyamin ◽

Muhammad Rashid Waqas

Keyword(s):

Salt Stress ◽

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Stress Conditions

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Biological control of chili damping off disease, caused by Pythium myriotylum

10.1101/2020.07.28.224519 ◽

2020 ◽

Author(s):

Sajjad Hyder ◽

Amjad Shahzad Gondal ◽

Zarrin Fatima Rizvi ◽

Muhammad Irtaza Sajjad Haider ◽

Muhammad Inam-ul-Haq

Keyword(s):

Plant Growth ◽

Plant Growth Promotion ◽

Growth Promotion ◽

Disease Suppression ◽

Root Weight ◽

Dual Culture ◽

Bacterial Isolates ◽

Damping Off ◽

Pythium Myriotylum ◽

Pgp Traits

ABSTRACTPythium myriotylum is a notorious soil-borne oomycete causes post-emergence damping off in chilli pepper. Of various disease management strategies, utilization of plant growth promoting rhizobacteria (PGPR) in disease suppression and plant growth promotion is eye catching strategy. The present study was performed to isolate and characterize PGPR indigenous to chili rhizosphere in Pakistan, and to test their potential to suppress damping off and plant growth promotion in chilli. Out of total 28 antagonists, 8 bacterial isolates (4a2, JHL-8, JHL-12, 1C2, RH-24, 1D, 5C and RH-87) significantly suppressed the colony growth of P. myriotylum in dual culture experiment. All the tested bacterial isolates were characterized for biochemical attributes, and 16S rRNA sequence based phylogenetic analysis identified these isolates as Flavobacterium spp., Bacillus megaterium, Pseudomonas putida, Bacillus cereus and Pseudomonas libanensis. All the tested bacterial isolates showed positive test results for ammonia production, starch hydrolase (except 4a2), and hydrogen cyanide production (except 4a2 and 1D). All the tested antagonists produced indole-3-acetic acid (13.4-39.0 μg ml−1), solubilized inorganic phosphate (75–103 μgml-1) and produced siderophores (17.1–23.7%) in vitro. All the tested bacterial isolates showed varied level of susceptibility and resistance response against different antibiotics and all these bacterial isolates were found non-pathogenic to chill seeds and notably enhanced percentage seed germination, plumule, redical length and vigor index over un-inoculated control. Additionally, under pathogen pressure, bacterization increased the defense related enzymes (PO, PPO and PAL) activates. Moreover, chilli seeds treatment with these bacterial isolates significantly suppressed damping-off caused by P. myriotylum, and improved PGP traits as compared to control. In addition, a positive correlation was noticed between shoot, root length and dry shoot and root weigh and a negative correlation was seen between dry shoot, root weight and seedling percentage mortality. These results showed that native PGPR possess multiple traits beneficial to the chilli plants and can be used to develop eco-friendly and effective seed treatment formulation as an alternative to synthetic chemical fungicides.

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