Abstract
Potato pectin falls to
Phytophthora
Phytophthora infestans
is a plant oomycete pathogen that drove the potato famines of the 1800s and continues to afflict potato fields today. The polysaccharide pectin makes up about a third of the cell wall in potatoes. Sabbadin
et al
. identified a family of lytic polysaccharide monooxygenases (LMPOs) that cleave pectin and are upregulated in
P. infestans
during infection. Silencing the relevant LMPO gene successfully inhibited
P. infestans
infections. These findings open doors for disease intervention targets and for biotech applications. —PJH
Virulence factors secreted by the plant pathogen
Phytophthora infestans
target pectin polysaccharides in plant cell walls.
The oomycete
Phytophthora infestans
is a damaging crop pathogen and a model organism to study plant-pathogen interactions. We report the discovery of a family of copper-dependent lytic polysaccharide monooxygenases (LPMOs) in plant pathogenic oomycetes and its role in plant infection by
P. infestans
. We show that LPMO-encoding genes are up-regulated early during infection and that the secreted enzymes oxidatively cleave the backbone of pectin, a charged polysaccharide in the plant cell wall. The crystal structure of the most abundant of these LPMOs sheds light on its ability to recognize and degrade pectin, and silencing the encoding gene in
P. infestans
inhibits infection of potato, indicating a role in host penetration. The identification of LPMOs as virulence factors in pathogenic oomycetes opens up opportunities in crop protection and food security.