Poplar defense against insects: genome analysis, full-length cDNA cloning, and transcriptome and protein analysis of the poplar Kunitz-type protease inhibitor family.
*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.
Michael Smith Laboratories, University of British Columbia, Vancouver, British Columbia, Canada.
Ryan N
RN
Philippe
Steven G
SG
Ralph
Carsten
C
Külheim
Sharon I
SI
Jancsik
Jörg
J
Bohlmann
D000818:Animals; D003001:Cloning, Molecular; D018076:DNA, Complementary; D020224:Expressed Sequence Tags; D020440:Gene Duplication; D015870:Gene Expression; D020869:Gene Expression Profiling; D017343:Genes, Plant; D018745:Genome, Plant; D007915:Lepidoptera; D046228:Microarray Analysis; D005810:Multigene Family; D010455:Peptides; D010802:Phylogeny; D010935:Plant Diseases / Q000235:genetics*; D010940:Plant Proteins / Q000235:genetics* / Q000378:metabolism; D032107:Populus / Q000235:genetics*; D011480:Protease Inhibitors / Q000378:metabolism*; D040901:Proteomics; D020133:Reverse Transcriptase Polymerase Chain Reaction
D018076:DNA, Complementary; D010455:Peptides; D010940:Plant Proteins; D011480:Protease Inhibitors