Genetic variation in tolerance of host monoterpenes in a population of the ascomycete canker pathogen Crumenulopsis sororia

Abstract

Twenty families of single‐ascospore isolates of the canker pathogen Crumenulopsis sororia were collected from eight trees of Pinus sylvestris in a native pinewood. Measurements were made of growth rate of each isolate in the presence and absence of a saturating atmosphere of the five principal monoterpenes of P. sylvestris cortical oleoresin (α‐pinene, β‐pinene, 3‐carene, β‐myrcene and limonene). All monoterpenes significantly reduced the mean linear growth rate of the C. sororia population. However, there was highly significant genetic variation among isolates in their tolerance of all five monoterpenes. The extent of genetic variation was greatest for β‐myrcene and limonene tolerance, and least for α‐pinene and 3‐carene tolerance. Significant positive correlations between tolerance of different monoterpenes were found, implying the presence of tolerance mechanisms common to a range of compounds.

The endophytic fungal community in leaves of a coastal redwood population diversity and spatial patterns

“…If indeed some of these leaf fungi are reacting to trees and sprouts as different substrates, one of the several factors that may influence substrate quality for these fungi is secondary compounds. Terpenoids occupy a prominent place among the secondary chemicals in redwood leaves (Hall & Langenheim, 1986), and they have differential fungistatic or fungitoxic effects on a variety of conifer-specialized fungi (Cobb et al, 1968;De Groot, 1972;Hall, 1985;Ennos & Swales, 1988). Since monoterpenes change in quantity and quality as redwood sprouts grow in height (Hall & Langenheim, 1986), these compounds may play a role in determining endophytic community composition in trees and sprouts.…”

Genetic Variation in a Fungal Pathogen: Response to Host Defensive Chemicals

“…In a random mating population of haploid organisms the ratio ofvariance among full-sib families to total phenotypic variance is an estimate of 112h 2 , and for half-sib families is an estimate ofl/4h 2 (see Appendix 1). Analysis of the mating system of C. sororia using isozyme markers suggests that there is no significant self-fertilization in the population and that the majority of progeny from a single apothecium are related as fullrather than half-sibs (Ennos and Swales, 1987). A conservative estimate of h?…”

“…In the present study, this difficulty was circumvented by using natural progenies from fruit bodies collected in the wild. Provided that information is available on the mating system of the species, such material can be used successfully to estimate quantitative genetic parameters (Lawrence, 1984;Ennos andSwales, 1987, 1988).…”

“…Isolates were obtained as natural progenies (chiefly full-sibs) to facilitate genetic analysis of any variation found (Ennos andSwales, 1987, 1988; Appendix 1). Performance of these isolates was then measured as growth rate in vitro in the presence and absence offive ofthe monoterpenes ofScots pine cortical resin.…”

“…), (b) Phenotypic correlations between percentage ofeach monoterpene in the resin of a sample of 6,705 trees from native pinewoods in Scotland (Forrest, unpubl.). canker surface (Ennos and Swales, 1987). Ascospores released during wet weather reinfect P. sylvestris (Hayes, 1975).…”