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Binti Hanifah, Nurul Atilia Shafienaz, 2022. Exploring growth promoting activity of rhizobacteria : insights into the molecular mechanisms underlying PGPR-plant interactions. Second cycle, A2E. Alnarp: SLU, Dept. of Plant Breeding (from 130101)

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The use of biocontrol agents with plant growh promoting activity has emerged as one of the approaches to support sustainable agriculture. From our previous field evaluation, four out of six rhizobacteria with biocontrol activity had a direct positive effect on potato plant height. This study aims to explore their growth promoting activity on tomato and potato plants and the possible molecular mechanisms involved. Four strains, Pseudomonas fluorescens 121, Serratia plymuthica S412, Serratia rubidaea 268, and S. rubidaea 119, were tested for growth promoting activity on tomato and potato plants grown in vitro and in pot experiments. The changes in the expression level of auxin-related genes were investigated. Under in vitro condition, 121 and 119 stimulated adventitious root development in the aerial plant part and shoot growth of potato. Meanwhile, growth promotion activity on in vitro grown tomato could not be observed due to technical issues such as seed contamination, ununiform seed germination and inconsistent results.
Inoculation with P. fluorescens 121 and S. rubidaea 119 altered the expression levels of selected auxin-related genes. P. fluorescens 121 transcriptionally upregulated StPIN1 in the root, StPIN5 in the shoot and StLAX5 and StPIN6 in both plant parts but downregulated StPIN6 in the root. Meanwhile, S. rubidaea 119 transcriptionally upregulated StPIN1 in the root, StLAX5 in the shoot and StPIN5 in both plant parts. These results suggest that both rhizobacteria enhanced polar auxin transport in the root and auxin homeostasis in both plant parts. In the pot experiment, potato plants with rhizobacteria applications showed higher yield and total dry weight than non-inoculated plants. In tomato, 121-treated plants had higher yield, plant height, total dry weight, number of leaves and chlorophyll content than other treatments. This study suggests that all rhizobacteria can be plant growth promoting rhizobacteria (PGPR) for potato, and P. fluorescens 121 exerts the best growth promoting effects on both crops.

Main title:Exploring growth promoting activity of rhizobacteria
Subtitle:insights into the molecular mechanisms underlying PGPR-plant interactions
Authors:Binti Hanifah, Nurul Atilia Shafienaz
Supervisor:Kalyandurg, Pruthvi Balachandra and Vetukuri, Ramesh
Examiner:Wang, Eu Sheng
Volume/Sequential designation:UNSPECIFIED
Year of Publication:2022
Level and depth descriptor:Second cycle, A2E
Student's programme affiliation:LM008 Horticultural Science Master's Programme, 120.0hp
Supervising department:(LTJ, LTV) > Dept. of Plant Breeding (from 130101)
Keywords:PGPR, adventitious root, root traits alteration, IAA production, volatile organic compounds, polar auxin transport, auxin homeostasis, Pseudomonas fluorescens, Serratia rubidaea, Serratia plymuthica, potato, tomato
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Subject. Use of subject categories until 2023-04-30.:Plant genetics and breeding
Plant physiology - Growth and development
Deposited On:26 Jan 2022 09:04
Metadata Last Modified:27 Jan 2022 02:01

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