Diploid Progenitors of Agrostis stolonifera L., Why Are They Important?.

Creeping bentgrass (Agrostis stolonifera L.) is a highly outcrossing allotetraploid (2n=4x=28) species important to the turfgrass industry.  The constituent diploid genomes of A. stolonifera are designated A2 and A3.  Colonial bentgrass (A. capillaris L.) is a segmental allotetraploid with the genome designations A1 and A2 and A. canina L., velvet bentgrass, is a diploid (2n=2x=14) and believed to be the source of the A1 genome.  These genomic descriptions were proposed by Keith Jones more than 50 years ago and were based on chromosome pairing behavior at metaphase I of meiosis in interspecies hybrids.  Contemporary genetic marker data does not strongly support the existing genome designations.  Understanding species relationships is critical to the effective use of a crops genetic diversity.  The richest source of genetic diversity is generally at the center of origin of the species.  In polyploid species the diploid progenitors at the center of origin can often be outcompeted by the more robust polyploids.  The diploids however, maintain higher levels of genetic diversity and are critical to polyploid improvement.  Currently neither of the diploid progenitors of A. stolonifera are known.  Using 1,359 MITE-display genetic markers, 175 diverse diploid Agrostis collections were tested to determine their relatedness to A. stolonifera and their level of genetic diversity.  Structure analysis was used to divide the accessions into groups based on the MITE-display genotype data.  Distinct diploid groups were identified and provide insights into the origins of A. stolonifera.  The data presented here is an important reference for Agrostis breeders interested in making further improvements in abiotic and biotic stress tolerance.