We studied the expression of the auxin responsive promoter (GH3) fused to the
gusA reporter gene in white clover (Trifolium repens cv.
Haifa) during the initiation of root galls by root-knot nematodes
(Meloidogyne javanica) to investigate whether nematode
infection affects auxin distribution in developing galls. In search for a
plant signal that would mediate changes in auxin location we studied the
induction of the flavonoid pathway because flavonoids can act as auxin
transport regulators. Three chalcone synthase (CHS1,
CHS2 and CHS3)
promoter:gusA fusions were examined in transgenic plants
and flavonoids were detected using fluorescence microscopy. Within 24 h post
inoculation CHS:gusA expression occurred around the
invading nematode. At 48 h post inoculation CHS:gusA
expression and flavonoids were detected throughout the infection site,
followed by high GH3:gusA expression in the gall
48–72 h post inoculation. Initially (48–72 h post inoculation)
high GH3:gusA expression in giant cell precursors was
followed by low expression in the enlarging giant cells (96–120 h post
inoculation), suggesting that auxin is needed as a trigger for giant cell
initiation but not for later enlargement. We suggest that nematodes control
auxin distribution in the root and that flavonoids could be responsible for
controlling auxin accumulation.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.