The Full-Size ABCG Transporters Nb-ABCG1 and Nb-ABCG2 Function in Pre- and Postinvasion Defense against Phytophthora infestans in Nicotiana benthamiana.
The sesquiterpenoid capsidiol is the major phytoalexin produced by Nicotiana and Capsicum species. Capsidiol is produced in plant tissues attacked by pathogens and plays a major role in postinvasion defense by inhibiting pathogen growth. Using virus-induced gene silencing-based screening, we identified two Nicotiana benthamiana (wild tobacco) genes encoding functionally redundant full-size ABCG (PDR-type) transporters, Nb-ABCG1/PDR1 and Nb-ABCG2/PDR2, which are essential for resistance to the potato late blight pathogen Phytophthora infestans Silencing of Nb-ABCG1/2 compromised secretion of capsidiol, revealing Nb-ABCG1/2 as probable exporters of capsidiol. Accumulation of plasma membrane-localized Nb-ABCG1 and Nb-ABCG2 was observed at the site of pathogen penetration. Silencing of EAS (encoding 5-epi-aristolochene synthase), a gene for capsidiol biosynthesis, reduced resistance to P. infestans, but penetration by P. infestans was not affected. By contrast, Nb-ABCG1/2-silenced plants showed reduced penetration defense, indicating that Nb-ABCG1/2 are involved in preinvasion defense against P. infestans Plastidic GGPPS1 (geranylgeranyl diphosphate synthase) was also found to be required for preinvasion defense, thereby suggesting that plastid-produced diterpene(s) are the antimicrobial compounds active in preinvasion defense. These findings suggest that N. benthamiana ABCG1/2 are involved in the export of both antimicrobial diterpene(s) for preinvasion defense and capsidiol for postinvasion defense against P. infestans.
Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
Yusuke
Y
Shibata
Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
Makoto
M
Ojika
Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji 611-0011, Japan.
Akifumi
A
Sugiyama
Laboratory of Plant Gene Expression, Research Institute for Sustainable Humanosphere, Kyoto University, Gokasho, Uji 611-0011, Japan.
Kazufumi
K
Yazaki
Research School of Biology, The Australian National University, Acton ACT 2601, Australia.
David A
DA
Jones
Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan.
Kazuhito
K
Kawakita
Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya 464-8601, Japan dtakemo@agr.nagoya-u.ac.jp.
Daigo
0000-0002-9816-7882
D
Takemoto
D000070996:ATP Binding Cassette Transporter, Subfamily G / Q000235:genetics / Q000378:metabolism*; D018506:Gene Expression Regulation, Plant / Q000235:genetics; D055750:Phytophthora infestans / Q000472:pathogenicity*; D010935:Plant Diseases / Q000235:genetics / Q000382:microbiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D014026:Nicotiana / Q000235:genetics / Q000378:metabolism* / Q000382:microbiology*
D000070996:ATP Binding Cassette Transporter, Subfamily G; D010940:Plant Proteins