Inheritance of two chlorophyll mutants in Eucalyptus globulus

Mutations in two independent genes causing chlorophyll deficiency (chl1 and chl2) were identified in two Eucalyptus globulus trees from remnant native forest. In each tree the proportion of albino progeny, following selfing, was found to be consistent with the segregation of a single gene. One of these genes (chl1) was found to be linked to the isozyme locus Gpi-2. The frequencies of the mutants were monitored in open-pollinated seed progeny and, from this, outcrossing rates were calculated. The rate of outcrossing in the chl1 mutant tree was also determined using a multi-locus, maximum likelihood estimation based on three isozyme loci, this agreed closely with the chl1 single locus estimate. This result highlights a role for rare, easily scored, mutants in seed orchards, where they can be utilized to monitor selfing rates.