Rhizosphere is the nutrient-rich soil surrounding plant roots, densely populated by various microorganisms, including bacteria that communicate with the plant. Some rhizobacteria can promote plant growth through different mechanisms and they are referred as plant growth promoting rhizobacteria (PGPR). Previously in the host laboratory, six bacterial species belonging to Bacillus, Microbacterium, Kocuria and Glutamicibacter genera, isolated from commercial compost, were tested revealing PGPR traits. This thesis work examines the interaction and the effects of these rhizobacteria on Solanum lycopersicum cultivar Micro-Tom. Tomato roots were inoculated with single bacterial species and the analysis were conducted at 3- and 7-days post inoculation. The measurement of specific root morphological traits showed that single bacterial species differently affect root growth and phenotypes. RNAseq analysis of plant transcriptome revealed differently expressed genes (DEG), in the comparison with uninoculated control plants, potentially related to bacterial effects on the plant. To examine bacteria spatial distribution along the root axis, some bacterial strains were transformed to express fluorescent-tag proteins, enabling the tracking of rhizobacteria. In particular, K. rhizophila expressing red fluorescent protein (RFP) was localized on tomato roots through confocal microscopy. Moreover, several adaptations to the transformation protocol were made in the attempt to improve the transformation efficiency of K. rhizophila, B. subtilis, B. licheniformis and Glutamicibacter sp.. Collectively, these analyses contribute to the description of these bacteria interaction with roots and of their effects on the plant, offering insights for further studies on their potential role in sustainable agricultural applications, in alignment with the EU Sustainable Development Goals 2030.

Role of compost rhizobacteria in shaping root morphology and modulating gene expression in Solanum lycopersicum

ZERBETTO, NICOLE
2023/2024

Abstract

Rhizosphere is the nutrient-rich soil surrounding plant roots, densely populated by various microorganisms, including bacteria that communicate with the plant. Some rhizobacteria can promote plant growth through different mechanisms and they are referred as plant growth promoting rhizobacteria (PGPR). Previously in the host laboratory, six bacterial species belonging to Bacillus, Microbacterium, Kocuria and Glutamicibacter genera, isolated from commercial compost, were tested revealing PGPR traits. This thesis work examines the interaction and the effects of these rhizobacteria on Solanum lycopersicum cultivar Micro-Tom. Tomato roots were inoculated with single bacterial species and the analysis were conducted at 3- and 7-days post inoculation. The measurement of specific root morphological traits showed that single bacterial species differently affect root growth and phenotypes. RNAseq analysis of plant transcriptome revealed differently expressed genes (DEG), in the comparison with uninoculated control plants, potentially related to bacterial effects on the plant. To examine bacteria spatial distribution along the root axis, some bacterial strains were transformed to express fluorescent-tag proteins, enabling the tracking of rhizobacteria. In particular, K. rhizophila expressing red fluorescent protein (RFP) was localized on tomato roots through confocal microscopy. Moreover, several adaptations to the transformation protocol were made in the attempt to improve the transformation efficiency of K. rhizophila, B. subtilis, B. licheniformis and Glutamicibacter sp.. Collectively, these analyses contribute to the description of these bacteria interaction with roots and of their effects on the plant, offering insights for further studies on their potential role in sustainable agricultural applications, in alignment with the EU Sustainable Development Goals 2030.
2023
Role of compost rhizobacteria in shaping root morphology and modulating gene expression in Solanum lycopersicum
Rhizobacteria
Tomato
Root
DEGs
Compost
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.12608/79743