Marker allozyme genes and alleles for differentiation of Populus deltoides, P. nigra, P. maximowiczii, and their interspecific hybrids

Abstract

Horizontal starch gel electrophoresis of enzymes was used to compare the allelic constitution of individuals of Populus deltoides Marsh., P. nigra L., P. maximowiczii Henry, P. ×canadensis Moench, and F₁ progeny of controlled crosses. Forty allozyme loci coding for 12 enzyme systems in root tips were observed. Populus deltoides, P. nigra, and P. maximowiczii were genetically distinct from each other. Each of these species had unique alleles at many loci, and one or two of these species also had some species-specific genes. Populus deltoides, P. nigra, and P. maximowiczii could be distinguished by mutually exclusive or unique alleles at any of the four allozyme loci Aco-2, Lap-1, Lap-2, and Pgi-2. Additionally, allozymes of Pgm-1, 6-Pgd-2, 6-Pgd-4, and 6-Pgd-5 could be used as markers to distinguish P. deltoides from P. nigra and P. maximowiczii, allozymes of Mdh-2, Per-3, Pgm-2, and Pgm-3 to distinguish P. nigra from P. deltoïdes and P. maximowiczii, and allozymes of Got-1, Got-4, and Pgi-1 to distinguish P. maximowiczii from P. deltoides and P. nigra. The observed marker allozyme genes and alleles can be effectively used for discriminating among the three Populus species and their interspecific hybrids, and identification and verification of paternity of progeny of single-pair and interspecific pollen-mix controlled crosses. Biochemical and molecular markers have significance in genetics, breeding, and systematics of these Populus species. Key words: Populus, allozymes, diagnostic genes and alleles, species and hybrid differentiation, enzyme electrophoresis.