Cold tolerance and seasonal gene expression in Dendroctonus ponderosae.

Gene expression analysis of overwintering mountain pine beetle larvae suggests multiple systems involved in overwintering stress, cold hardiness, and preparation for spring development

“…This suggests that production of glycerol is increased between September and November, in agreement with previous work ( Fraser , 2011 ). Also in agreement with Fraser ( 2011 ), our results further suggest that glycerol is biosynthesized via dihydroxyacetone phosphate (DHAP) and glycerol-3-phosphate (G3P) rather than via glyceraldehyde ( Fig. 2 ).…”

“…Glycerol is a known cryoprotectant in mountain pine beetle and is one of the few metabolites that have been shown to accumulate in overwintering larvae ( Bentz & Mullins, 1999 ). Our results support the importance of glycerol production in early winter and support similar quantitative RT-PCR results found in overwintering larvae in Fraser ( 2011 ) and J Fraser (2010, unpublished data); studies that were conducted using overwintering larvae collected concurrently with the larvae sampled for this study. Key enzymes in the two catalytic steps preceding the final synthesis of glycerol were significantly up-regulated between September and November ( Fig.…”

“…2 ). Although the glyceraldehyde route could conceivably also be responsible for increased glycerol synthesis in some circumstances, we did not find evidence for this pathway in our data set, which supports the findings in Fraser ( 2011 ) as well.…”

“…An asterisk indicates a significant fold change within the two time points measured within each sampling period (Bonferroni adjusted p -value < 0.001). The diagram on the right illustrates a subset of the glycerol biosynthetic pathway (modified with permission from Fraser , 2011 ) showing the location G3PDH and GK as the enzymes that catalyze the steps immediately preceding the production of glycerol. Metabolites are shown in ovals: dihydroxyacetone phosphate (DHAP), glycerol-3-phosphate (G3P), glyceraldehyde (GA); enzymes are shown in rectangles: glycerol-3-phosphate dehydrogenase (G3PDH), glycerol kinase (GK), alcohol dehydrogenase (ADH).…”