Page 2 Plant-Bacteria Interactions Edited by Iqbal Ahmad, John ...

126j 6 Molecular Mechanisms Underpinning Plant Colonization
6.5
Concluding Remarks and Future Perspectives
Significant progress has been made in unraveling the molecular mechanisms that
underpin plant colonization by the model plant growth-promoting rhizobacterium
P. fluorescens SBW25. This has been greatly advanced by the development and
application of a number of advanced genetic tools for SBW25, including IVET,
SPyVET and RIVET, in conjunction with the availability of the SBW25 genome
sequence. Investigations to date have identified genes that are specifically induced
in the plant environment, offering insights into the regulatory networks that control
them. The contributions of plant-induced genes to bacterial fitness during plant
colonization have also been investigated in many cases, and it has been found that
not all plant-induced genes contribute to fitness. A foundation model for the regulatory
networks influencing plant-induced genes has been established, and this has
provided a valuable knowledge base with which to begin to understand the responses
of SBW25 to the plant environment.
Future investigations into the genetic bases underlying plant colonization are
likely to focus on teasing apart the complex regulatory networks that control both
plant-induced genes and genes in general. The scale of these types of analyses is
enormous and will require a highly in-depth and multidisciplinary approach. With
functional genomics technologies becoming more readily accessible, such as transcriptomics,
proteomics and metabolomics, the application of these to SBW25 will
greatly enhance our understanding of its biology. However, to relate these data to
behavior in the complex plant environment, the development and use of additional
in situ based tools will almost certainly be required. These data will provide an
important contribution to our understanding of the molecular bases underpinning
plant colonization, and in particular, identification and characterization of the key
genes and traits required for colonization will likely advance our understanding of
field requirements for PGPR enabling enhanced performance of biocontrol strains.
Acknowledgments
SRG is funded by the Leverhulme Trust. We thank Paul B. Rainey for support and
helpful discussion.
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