Organelle DNA Diversity among Buffalograsses from the Great Plains of North America Determined by cpDNA and mtDNA RFLPs

Buffalograss [Buchloe dactyloides (Nutt.) Engelm.] is a perennial, warm-season turfgrass that is native to the shortgrass prairie of North America. It offers potential benefits as a turfgrass because of its drought resistance, low incidence of pest problems, and relatively low nutrient requirements. This study was initiated to evaluate the level of organelle DNA diversity among buffalograss genotypes and to determine the mode of inheritance of the chloroplast organelle by cpDNA and mtDNA PCR-RFLPs. The 56 genotypes studied included diploids, triploid, tetraploids, pentaploids, and hexaploids. These genotypes represented 273 buffalograsses collected during 1994 and 1995 from diverse locations in the North American Great Plains. Six cpDNA and three mtDNA noncoding regions were amplified by polymerase chain reaction, using universal chloroplast and mitochondrial primer pairs. Each amplified fragment was digested with two to six different restriction enzymes. On the basis of the use of cpDNA primers, psbC-trnS, and restriction enzyme HaeIII, cpDNA was determined to be maternally inherited in buffalograss. Of the 225 scored fragments, 189 were polymorphic (84%), which included the outgroups, perennial ryegrass (Lolium perenne L.) and blue grama [Bouteloua gracilis (H.B.K.) Lag. Ex Steud.]. Similarities among all genotypes ranged from 0.41 to 1.0, with a mean of 0.70. The UPGMA-generated dendrogram clustered all buffalograsses together with the similarity value of 0.95. Out of the 56 genotypes studied, nine (16%) were discriminated from the other buffalograsses. The remaining 47 genotypes did not differ for cpDNA and mtDNA PCR-RFLPs even though they represented diverse geographic origins and five ploidy levels. These results suggest that low levels of organelle DNA PCR-RFLP are present in naturally occurring buffalograss populations