Chloroplast DNA variation and inheritance in waxflowers (Myrtaceae)

Abstract

A study of chloroplast DNA variation and inheritance in waxflowers (Myrtaceae) was undertaken as a basis for validating parentage in putative, juvenile hybrid plants and in naturally occurring hybrids. Polymerase chain reaction amplification of three chloroplast DNA regions, followed by restriction of the amplified products, was used to identify restriction fragment length polymorphisms (RFLP) in 18 Chamelaucium uncinatum and C. megalopetalum genotypes. Five cpDNA haplotypes were observed within the two species studied. In C. uncinatum, three site mutations and one length mutation were observed, corresponding to three cpDNA haplotypes; and in C. megalopetalum, two cpDNA haplotypes were observed.

Chloroplast DNA (cpDNA) inheritance was studied in 17 intraspecific and 33 interspecific hybrids by using the cpDNA polymorphisms between the female and the male parents. Maternal cpDNA inheritance was observed in all cases, as in most angiosperms. These results support a 95.5% probability of maternal cpDNA inheritance in waxflowers at the 90% confidence level.

The method has been used to identify maternal parents of naturally occurring hybrids in our waxflower breeding program. It may also be applied to the study of the evolution of natural populations and, in this study, indicates distinct lines of evolution for individual populations of the two species.