Poplar defense against insects: genome analysis, full-length cDNA cloning, and transcriptome and protein analysis of the poplar Kunitz-type protease inhibitor family

Date

2009

Authors

Philippe, Ryan N.
Ralph, Steven G.
Kulheim, Carsten
Jancsik, Sharon I.
Bohlmann, Joerg

Journal Title

Journal ISSN

Volume Title

Publisher

Cambridge University Press

Abstract

Kunitz protease inhibitors (KPIs) feature prominently in poplar defense responses against insects. The increasing availability of genomics resources enabled a comprehensive analysis of the poplar (p)KPI family. Using genome analysis, expressed sequence tag (EST) mining and full-length (FL)cDNA cloning we established an inventory and phylogeny of pKPIs. Microarray and real-time PCR analyses were used to profile pKPI gene expression following real or simulated insect attack. Proteomics of insect midgut content was used to monitor stability of pKPI protein. We identified 31 pKPIs in the genome and validated gene models by EST mining and cloning of 41 unique FLcDNAs. Genome organization of the pKPI family, with six poplar-specific subfamilies, suggests that tandem duplications have played a major role in its expansion. pKPIs are expressed throughout the plant and many are strongly induced by insect attack, although insect-specific signals seem initially to suppress the tree pKPI response. We found substantial peptide coverage for a potentially intact pKPI protein in insect midgut after eating poplar leaves. These results highlight the complexity of an important defense gene family in poplar with regard to gene family size, differential constitutive and insect-induced gene expression, and resilience of at least one pKPI protein to digestion by herbivores.

Description

Keywords

Keywords: complementary DNA; peptide; proteinase inhibitor; vegetable protein; deciduous tree; DNA; enzyme activity; gene expression; genetic analysis; genomics; inhibitor; phylogeny; plant defense; plant-herbivore interaction; plant-insect interaction; polymerase Choristoneura rosaceana (oblique-banded leaf roller); Malacosoma disstria (forest tent caterpillar); Plant defense; Plant-herbivore interaction; Populus trichocarpa (cottonwood); Tree genomics

Citation

Source

New Phytologist

Type

Journal article

Book Title

Entity type

Access Statement

License Rights

DOI

10.1111/j.1469-8137.2009.03028.x

Restricted until

2037-12-31