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Root colonisation of P seudomonas aeruginosa strain UPMP 3 and induction of defence‐related genes in oil palm ( E laeis guineensis )
Author(s) -
Sathyapriya H.,
Sariah M.,
Siti Nor Akmar A.,
Wong M.
Publication year - 2012
Publication title -
annals of applied biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.677
H-Index - 80
eISSN - 1744-7348
pISSN - 0003-4746
DOI - 10.1111/j.1744-7348.2011.00525.x
Subject(s) - biology , elaeis guineensis , colonisation , strain (injury) , exudate , pseudomonas aeruginosa , microbiology and biotechnology , botany , xylem , root hair , horticulture , colonization , bacteria , gene , food science , palm oil , biochemistry , genetics , anatomy
P seudomonas aeruginosa strain UPMP 3 labelled with β ‐glucuronidase ( gusA ) and green fluorescent protein ( gfp ) by electrotransformation yielded ca 1 × 10 7 transformants µg −1 DNA . The data obtained from the dilution plate count showed that over 28 days both epiphytic and endophytic populations of P . aeruginosa strain UPMP 3 increased from 5.76 log 10 [colony forming unit ( CFU ) + 1] g −1 fresh weight ( FW ) to 8.19 log 10 ( CFU + 1) g −1 FW and 4.10 log 10 ( CFU + 1) g −1 FW to 6.23 ( CFU + 1) g −1 FW , respectively. Confocal laser scanning microscopic analysis of oil palm roots treated with gusA :gfp ‐tagged P . aeruginosa strain UPMP 3 showed intense root colonisation over the sampling period. The root surface colonisation by P . aeruginosa strain UPMP 3 was followed by a second stage, characterised by cortical infection, and a third stage, which involves xylem ingression. The colonisation of oil palm roots by the gusA :gfp ‐tagged strain was concentrated on root areas potentially rich in nutrients such as the elongation zones, ridges between epidermal cells and points of secondary adventitious root emergence. Different expression levels of defence‐related genes, namely, chitinase and β ‐1,3‐ glucanase in the strain UPMP 3–host interaction recorded over 28 days, suggested the potential role of P . aeruginosa strain UPMP 3 in triggering the defence mechanism in oil palm. This is the first report on root colonisation and upregulation of defence‐related genes on oil palm roots by P . aeruginosa strain UPMP 3 and shows the potential of this strain to be used as a biocontrol agent in oil palm.