GERMPLASM DIVERSITY AMONG CULTIVARS AND THE NPGS CRIMSON CLOVER COLLECTION

Crimson clover (Trifolium incarnatum L.) is a cool-season annual forag e legume. Few morphological traits are recorded to distinguish genotyp es and very little is known about its genetic diversity. The objective of this research was to classify and characterize the genetic diversi ty in the USDA-ARS National Plant Germplasm System (NPGS) accessions a nd USA and European Economic Community (EEC) cultivars. Descriptions o f EEC cultivars and their breeding histories are also presented. A sec ondary objective was to determine if T. incarnatum var. molinerii (Bal b. ex Hornem.) Ser. should be considered a distinct species. Genomic D NA from leaves of 37 taxa was examined in 1993 by the polymerase chain reaction (PCR) using 29 random amplified polymorphic DNA (RAPD) marke rs. Plants grown in the greenhouse were also observed for inflorescenc e color and relative flowering time. Cluster analysis of pairwise mean s of RAPD maker distances and cultivar pedigree histories revealed sim ilar genetic backgrounds among most cultivars. Flower color was associ ated with RAPD marker grouping (P less than or equal to 0.02) but flow ering time was not (P less than or equal to 0.31). Both red vs. non-re d inflorescence color and early-vs. late-flowering traits could be pre dicted by specific RAPD bands (95 and 93% accuracy, respectively). Ana lysis of internal transcribed spacer region sequences (ITS) from ribos omal DNA (rDNA) showed diverse crimson clover taxon to be more similar to one another than to var. molinerii (0.4 and 0.9% base pair differe nces, respectively; P less than or equal to 0.001). Because of the lim ited diversity within the current NPGS collection, additional accessio ns should be collected, morphologically evaluated, and genetically ana lyzed to broaden the genetic base of the collection. Crimson clover va r. molinerii is a sister taxa of more typical crimson clover accession s but exhibits enough ITS diversity to be classified as another specie s.