GENETIC DIVERSITY IN HARD RED SPRING WHEAT-BASED ON SEQUENCE-TAGGED-SITE PCR MARKERS

Genetic variation among wheat (Triticum aestivum L.) parents is necessary to derive superior progeny from crossing and selection. However, crosses are often performed among elite lines with similar agronomic and end-use characteristics. Thus, the potential exists for an undesirable narrowing of the germplasm base for any particular class of wheat. The relative genetic diversity within hard red spring wheat was determined in comparison to a sample of wheat accessions representing an array of types and geographic origins. Three groups of accessions were assayed for the frequencies of DNA polymorphism using a total of 38 sequence-tagged-she primer sets with polymerase chain reaction. Group I contained 10 elite hard red spring wheat cultivars under production in Montana and North Dakota, Group II included 15 hard red spring wheat cultivars and lines from the North American Great Plains, and Group III contained 20 accessions representing a wide range of collection and morphological types. Twenty-four of 38 primer sets (63%) and 31 of 76 primer-enzyme combinations (41%) revealed polymorphisms. The range of genetic similarity estimated by percentage of shared restriction fragments varied from 0.65 to 0.99 among all pairwise comparisons among the 45 lines. Average genetic similarity was 0.81. Genetic similarity among the hard red spring wheats was 0.88, whereas genetic similarity among the broadly based Group III was 0.78. Our results showed that the breeding pool for hexaploid hard red spring wheat is narrow relative to levels of diversity among and within classes in hexaploid wheat.