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Plant Physiol

Title:		Functional analysis of the Kunitz trypsin inhibitor family in poplar reveals biochemical diversity and multiplicity in defense against herbivores
Author(s):		Major IT; Constabel CP;
Address:		"Centre for Forest Biology and Department of Biology, University of Victoria, Victoria, BC, Canada"
Journal Title:		Plant Physiol
Year:		2008
Volume:		20071116
Issue:		3
Page Number:		888 - 903
DOI:		10.1104/pp.107.106229
ISSN/ISBN:		0032-0889 (Print) 1532-2548 (Electronic) 0032-0889 (Linking)
Abstract:		"We investigated the functional and biochemical variability of Kunitz trypsin inhibitor (KTI) genes of Populus trichocarpa x Populus deltoides. Phylogenetic analysis, expressed sequence tag databases, and western-blot analysis confirmed that these genes belong to a large and diverse gene family with complex expression patterns. Five wound- and herbivore-induced genes representing the diversity of the KTI gene family were selected for functional analysis and shown to produce active KTI proteins in Escherichia coli. These recombinant KTI proteins were all biochemically distinct and showed clear differences in efficacy against trypsin-, chymotrypsin-, and elastase-type proteases, suggesting functional specialization of different members of this gene family. The in vitro stability of the KTIs in the presence of reducing agents and elevated temperature also varied widely, emphasizing the biochemical differences of these proteins. Significantly, the properties of the recombinant KTI proteins were not predictable from primary amino acid sequence data. Proteases in midgut extracts of Malacosoma disstria, a lepidopteran pest of Populus, were strongly inhibited by at least two of the KTI gene products. This study suggests that the large diversity in the poplar (Populus spp.) KTI family is important for biochemical and functional specialization, which may be important in the maintenance of pest resistance in long-lived plants such as poplar"
Keywords:		"Amino Acid Sequence Animals Gastrointestinal Tract/enzymology Gene Expression Regulation, Developmental Gene Expression Regulation, Plant Genetic Variation Host-Parasite Interactions/*genetics Larva/enzymology Molecular Sequence Data Moths/*enzymology Mul;"
Notes:		"MedlineMajor, Ian T Constabel, C Peter eng Research Support, Non-U.S. Gov't 2007/11/21 Plant Physiol. 2008 Mar; 146(3):888-903. doi: 10.1104/pp.107.106229. Epub 2007 Nov 16"