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Xylem monoterpenes of pines: distribution, variation, genetics, function

Informally Refereed

Abstract

The monoterpenes of about 16,000 xylem resin samples of pine (Pinus) speciesand hybrids—largely from the western United States—were analyzed in this long-term study of the resistance of pines to attack by bark beetles (Coleoptera:Scolytidae), with special emphasis on resistance to the western pine beetle(Dendroctonus brevicomis). The samples were analyzed by gas liquid chromatography, and the results reported are expressed as normalized monoterpene composition. Optical isomers were not separated. The studycovered (a) 19 pine species in California, (b) 86 pine hybrids and 26 parentspecies at the Pacific Southwest Research Station’s Insitute of Forest Genetics, (c)21 half sibling populations of Pinus ponderosa Dougl. ex Laws., (d) 56 full siblingpopulations of P. ponderosa, (e) interspecific and intraspecific pine grafts, (f)effects of procedural parameters, and (g) bioassay of resistance to Dendroctonusbrevicomis. The results suggested that (a) these monoterpenes and associatedhydrocarbons were primarily controlled by genes in pine xylem—hepane,undecane, a-pinene, ß-pinene, 3-carene, sabinene, myrcene, limonene, ß-phellandrene—and evidence strongly suggested a pair of additive alleles foreach monoterpene that competes with each other for a fixed amount of a fivecarbonprecursor; (b) all of these might also be produced by isomerization andpossibly may be byproducts of biosynthesis of other monoterpenes; (c) thequantity of all these can be modified by several environmental factors oftenassociated with forms of stress, and possibly by other minor genetic factors; an(d) these monoterpenes were not controlled by genes in pines but are probablythe results of isomerization and byproducts of biosynthesis: a-thujene, nonane,camphene, ?-terpenene, ocimene, a-phellandrene, and terpinolene

Keywords

Pinus species, pine grafts, bark beetles, western pine beetles, gas liquid chromatography, California.

Citation

Smith, Richard. 2000. Xylem monoterpenes of pines: distribution, variation, genetics, function. Gen. Tech. Rep. PSW-GTR-177. Albany, CA: Pacific Southwest Research Station, Forest Service, U.S. Department of Agriculture; 454 p.
Citations
https://www.fs.usda.gov/research/treesearch/6775