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F. Cervone - Plant innate immunity: cell wall-mediated signalling and recognition in plant defense
OGs, resistance to fungal infection is suppressed by
exogenous auxin, whereas sensitivity to auxin of PG
plants is reduced in different bioassays. The altered
plant defense responses and auxin sensitivity in PG
plants may reflect an increased accumulation of OGs
and subsequent antagonism of auxin action.
Alternatively, it may be a consequence of perturbations
of cellular physiology and elevated defense status
as a result of altered cell wall architecture.
A way of altering pectin susceptibility to hydrolysis
by microbial endopolygalacturonases is the constitutive
expression of specific protein inhibitors of
pectin methylesterases (the genes AtPMEI-1 and
AtPMEI-2 of Arabidopsis thaliana). The overexpression
of the inhibitors decreases PME activity and
increases the degree of pectin methylesterification by
about 16%. Transformed plants show a slight but significant
increase in root length and are more resistant
to Botrytis cinerea. The reduced symptoms caused by
the fungus on transgenic plants are related to its
impaired ability to grow on methylesterified pectins.
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Selected publications
Ferrari S, Galletti R, Denoux C, De Lorenzo G,
Ausubel FM, Dewdney J. Resistance to Botrytis
cinerea induced in Arabidopsis by elicitors is independent
of salicylic acid, ethylene, or jasmonate signaling
but requires PHYTOALEXIN DEFI-
CIENT3. Plant Physiology 2007, 144:367-79.
Lionetti V, Raiola A, Camardella L, Giovane A, Obel
N, Pauly M, Favaron F, Cervone F, Bellincampi D.
Overexpression of pectin methylesterase inhibitors
in Arabidopsis restricts fungal infection by Botrytis
cinerea. . Plant Physiology 2007, 143:1871-80.
Ferrari S, Galletti R, Pontiggia D, Manfredini C,
Lionetti V, Bellincampi D, Cervone F, De Lorenzo G.
Transgenic expression of a fungal endo-polygalacturonase
increases plant resistance to pathogens and
reduces auxin sensitivity. Plant Physiology 2008,
146:669-81.