Insect attack and wounding induce traumatic resin duct development and gene expression of (-)-pinene synthase in Sitka spruce.
Conifers possess inducible terpenoid defense systems. These systems are associated with the formation of traumatic resin ducts (TRD) and are underpinned by enhanced gene expression and activity of terpene synthases (TPS), enzymes responsible for oleoresin formation. We first determined that Sitka spruce (Picea sitchensis [Bong.] Carriere) had the capacity for TRD formation by mechanically wounding representative trees. We then proceeded to investigate whether the white pine weevil (Pissodes strobi Peck.), a stem-boring insect, can influence the expression of genes encoding monoterpene synthases (mono-tps) in Sitka spruce. We went on to compare this response with the effects of a simulated insect attack by drill wounding. A significant increase in mono-tps transcript level was observed in the leaders of lateral branches of weevil-attacked and mechanically wounded trees. In this study, weevils induced a more rapid enhancement of mono-tps gene expression. A full-length Sitka spruce mono-tps cDNA (PsTPS2) was isolated, expressed in Escherichia coli, and functionally identified as (-)-pinene synthase. The recombinant (-)-pinene synthase catalyzes the formation of (-)-alpha-pinene and (-)-beta-pinene, both of which are known constituents of stem oleoresin in Sitka spruce and increase in abundance after weevil attack. These data suggest that increased (-)-pinene synthase gene expression is an important element of the direct defense system deployed in Sitka spruce after insect attack.
McKay
S Ashley Byun
SA
Department of Biological Sciences, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada.
Hunter
William L
WL
Godard
Kimberley-Ann
KA
Wang
Shawn X
SX
Martin
Diane M
DM
Bohlmann
Jörg
J
Plant
Aine L
AL
D000595:Amino Acid Sequence; D000818:Animals; D000081008:Bicyclic Monoterpenes; D001643:Bridged Bicyclo Compounds / Q000737:chemistry / Q000378:metabolism; D019757:Carbon-Oxygen Lyases / Q000235:genetics / Q000378:metabolism*; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D018506:Gene Expression Regulation, Plant; D007113:Immunity, Innate / Q000235:genetics; D007313:Insecta / Q000254:growth & development*; D008969:Molecular Sequence Data; D039821:Monoterpenes / Q000737:chemistry / Q000378:metabolism; D010802:Phylogeny; D028222:Picea / Q000201:enzymology* / Q000235:genetics / Q000469:parasitology; D010935:Plant Diseases / Q000235:genetics / Q000469:parasitology*; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism; D018514:Plant Structures / Q000201:enzymology / Q000235:genetics / Q000254:growth & development; D012116:Resins, Plant / Q000378:metabolism*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D013314:Stress, Mechanical
D000081008:Bicyclic Monoterpenes; D001643:Bridged Bicyclo Compounds; D018076:DNA, Complementary; D039821:Monoterpenes; D010940:Plant Proteins; D012116:Resins, Plant; C010789:beta-pinene; D019757:Carbon-Oxygen Lyases; C473195:(-)-alpha-pinene synthase; C005451:alpha-pinene