Genetic variation in the frost hardiness of Podocarpus totara

Abstract

The late-winter frost hardiness of seedlings of eight provenances of totara (Podocarpus totara G. Benn. ex Don) raised in a common environment was tested in a controlled environment frost room. Frost damage was assessed visually. Frost hardiness temperatures of the provenances ranged from -5°C to -10°C. A significant increase in frost damage occurred at lower temperatures, and the frost hardiness of the provenances was positively comelated with their altitude of origin.

The possibility of allele frequency-dependent selection for alleles correlated with frost hardiness was explored by apreliminary isozyme analysis of four variable loci in new foliage of totara seedlings. Allele frequencies at one locus of isocitrate dehydrogenase (Idh-1) appeared significantly correlated with provenance frost hardiness.

These results suggest that environmental pressures have selected far frost hardiness in totara, and resulted in the evolution of populations of totara adapted to current local climates.

Keywords:

• Podocarpus totara
• totara
• frost hardiness
• isozyme analysis
• selection pressures
• genetic variation