Transgenic expression of a fungal endo-polygalacturonase increases plant resistance to pathogens and reduces auxin sensitivity.
Polygalacturonases (PGs), enzymes that hydrolyze the homogalacturonan of the plant cell wall, are virulence factors of several phytopathogenic fungi and bacteria. On the other hand, PGs may activate defense responses by releasing oligogalacturonides (OGs) perceived by the plant cell as host-associated molecular patterns. Tobacco (Nicotiana tabacum) and Arabidopsis (Arabidopsis thaliana) plants expressing a fungal PG (PG plants) have a reduced content of homogalacturonan. Here, we show that PG plants are more resistant to microbial pathogens and have constitutively activated defense responses. Interestingly, either in tobacco PG or wild-type plants treated with 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.
Dipartimento di Biologia Vegetale, Università degli Studi di Roma La Sapienza, 00185 Rome, Italy.
Simone
S
Ferrari
Roberta
R
Galletti
Daniela
D
Pontiggia
Cinzia
C
Manfredini
Vincenzo
V
Lionetti
Daniela
D
Bellincampi
Felice
F
Cervone
Giulia
G
De Lorenzo
D017360:Arabidopsis / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology; D001234:Aspergillus niger / Q000201:enzymology* / Q000235:genetics; D020171:Botrytis / Q000502:physiology; D015870:Gene Expression; D007210:Indoleacetic Acids / Q000494:pharmacology*; D008969:Molecular Sequence Data; D010935:Plant Diseases / Q000382:microbiology*; D030821:Plants, Genetically Modified; D011096:Polygalacturonase / Q000235:genetics / Q000378:metabolism*; D044224:Pseudomonas syringae / Q000502:physiology; D014026:Nicotiana / Q000187:drug effects / Q000235:genetics* / Q000378:metabolism / Q000382:microbiology
D007210:Indoleacetic Acids; D011096:Polygalacturonase