BH72 has been studied for nitrogenfixation abilities at genomic level and complete
genome was matched with related soil- and plant-associated bacteria (Hurek and
Reinhold-Hurek 2003 ; Krause et al. 2006 ). Many plant-associated bacteria and
pathogens contain N-acyl homoserine lactone-(AHL) for quorum-sensing system
(Preston et al. 2001 ; Buttner and Bonas 2006 ). Nevertheless, (Krause et al. 2006 )
another factor for plant microbe interaction has been identified encoded by BH72
genome. It includes Tpe I and II protein secretion system with Type IV surface
polysaccharides on pili, andflagella so as to produce chemotaxis proteins and ferric
siderophore uptake systems. The valuable biological insight was provided by BH72
genome. In this perspective, it is clear that as much genome sequences of endophyte
will be available, much exploration of the mechanisms involved in successful
endophyte colonization.
7.5 Post Genomic View of Bacterial EndophyteS
Metagenomics analysis of endophytic bacteria associated with rice plant confirmed
few traits that also exist in endophytes. Therefore, these traits evaluated through
genomic analysis become potentially important for their interactions with plants.
These include entire set of highly specialized bacterial secretion system, except type
III due to its non-conserved nature among endophytes that are associated with rice
plants. On the other hand, production of cellulolytic and pectinolytic enzymes are of
major concerns along with the production of glagellins. Majority of other enzyme
also involved in these interactions in terms of degradation of reactive oxygen
species (ROS). Further, receptors and transporters for iron uptake also play sig-
nificant role in intracellular microbial interaction with plant through
quorum-sensing systems(QS). Several degradative pathways of plant metabolites
and various plant growth-promoting and biocontrol traits such as ACC-deaminase
activity, biological nitrogenfixation (BNF) and production of phytohormones and
volatile and non-volatile antimicrobial compounds.
Applying postgenomic approaches, such as metaproteomisa, metaproteoge-
nomics and metatranscriptomics, can link genomic potential with plant–endophyte
interactions. Recently, a metaproteogenomic approach was used to study the
microbial communities in the phyllosphere and rhizosphere of rice (Knief et al.
2011 ).
7.6 Plant Growth-Promoting Endophytes
Some of the endophytes act as biocontrol agents while others increase plant growth
through the production of nutrients and minerals such as nitrogen, phosphate and
other nutrients. Infact, quite a few endophytic bacterial genera such as
7 Role of Bacterial Endophytes in Plant Disease Control 141