Wound-induced terpene synthase gene expression in Sitka spruce that exhibit resistance or susceptibility to attack by the white pine weevil.
We analyzed the expression pattern of various terpene synthase (TPS) genes in response to a wounding injury applied to the apical leader of Sitka spruce (Picea sitchensis Bong. Carr.) genotypes known to be resistant (R) or susceptible (S) to white pine weevil (Pissodes strobi Peck.) attack. The purpose was to test if differences in constitutive or wound-induced TPS expression can be associated with established weevil resistance. All wounding treatments were conducted on 9-year-old R and S trees growing under natural field conditions within the range of variation for weevil R and S genotypes. Representative cDNAs of the monoterpene synthase (mono-TPS), sesquiterpene synthase (sesqui-TPS), and diterpene synthase (di-TPS) classes were isolated from Sitka spruce to assess TPS transcript levels. Based on amino acid sequence similarity, the cDNAs resemble Norway spruce (Picea abies) (-)-linalool synthase (mono-TPS; PsTPS-Linl) and levopimaradiene/abietadiene synthase (di-TPS; PsTPS-LASl), and grand fir (Abies grandis) delta-selinene synthase (sesqui-TPS; PsTPS-Sell). One other mono-TPS was functionally identified as (-)-limonene synthase (PsTPS-Lim). No significant difference in constitutive expression levels for these TPSs was detected between R and S trees. However, over a postwounding period of 16 d, only R trees exhibited significant transcript accumulation for the mono- and sesqui-TPS tested. Both R and S trees exhibited a significant accumulation of PsTPS-LASl transcripts. An assessment of traumatic resin duct formation in wounded leaders showed that both R and S trees responded by forming traumatic resin ducts; however, the magnitude of this response was significantly greater in R trees. Collectively, our data imply that the induced resinosis response is an important aspect of defense in weevil R Sitka spruce trees growing under natural conditions.
Byun-McKay
Ashley
A
Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia, Canada.
Godard
Kimberley-Ann
KA
Toudefallah
Morteza
M
Martin
Diane M
DM
Alfaro
Rene
R
King
John
J
Bohlmann
Joerg
J
Plant
Aine L
AL
D019883:Alkyl and Aryl Transferases / Q000235:genetics* / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D003001:Cloning, Molecular; D018506:Gene Expression Regulation, Plant; D005838:Genotype; D007113:Immunity, Innate / Q000235:genetics; D008969:Molecular Sequence Data; D010802:Phylogeny; D028222:Picea / Q000033:anatomy & histology / Q000201:enzymology* / Q000235:genetics; D018520:Plant Shoots / Q000033:anatomy & histology / Q000201:enzymology / Q000235:genetics; D016415:Sequence Alignment; D048889:Weevils / Q000472:pathogenicity*
D019883:Alkyl and Aryl Transferases; C108877:terpene synthase