Assessment of Genetic Diversity among U.S. Runner‐Type Peanut Cultivars Using Simple Sequence Repeat Markers

Abstract

The scientific community has long assumed that plant breeding activities decrease genetic diversity in crop species. To determine the influence of plant breeding on peanut, this study was designed to assess allelic diversity changes among peanut (Arachis hypogaea L.) cultivars of the runner market type using simple sequence repeat (SSR) markers. All runner‐type cultivars released to date were included with the exception of ten cultivars released in the 2000s. Thirty‐four SSR primer pairs amplified a total of 154 alleles. The results indicated that (i) at the gene level, allelic diversity has increased significantly through decades of breeding, (ii) at the population level, genetic diversity was at its lowest during the pre‐1980s time period and gradually increased in each subsequent decade, and (iii) most of the observed SSR variation occurred within, rather than among time periods. A principal coordinate analysis (PCO) clearly demonstrated increases in the variation present in each subsequent breeding decade, reaching its maximum in the 2000s. Therefore, it appears that runner‐type peanut breeders have been successful at developing improved peanut cultivars while increasing levels of diversity in the last three decades of breeding. In addition, genetic relationships among cultivars reported in this study might be of use for peanut breeders when selecting parents for establishment of breeding populations.

Genome-wide SNP Genotyping Resolves Signatures of Selection and Tetrasomic Recombination in Peanut

“… Milla-Lewis et al. (2010) published a study of the genetic diversity in US runner cultivars using 34 SSR markers.…”

Analysis of genetic diversity and population structure of peanut cultivars and breeding lines from China, India and the US using simple sequence repeat markers

“…Among the US lines tested in this study, 70% were the Runner type, and the 16 peanut lines from the ACI‐US group were mostly advanced breeding lines. Although Runner‐type peanut breeders have been successful at increasing levels of diversity among cultivars released in the last three decades of modern plant breeding, because the Runner market type was derived from fewer ancestry lines than the Virginia market type, they have a lower genetic diversity than the Virginia market type (Milla‐Lewis et al ). This may be the reason why US peanut lines had lower genetic diversity than the other two countries in this study.…”

“…One possibility may be related to the limited genetic diversity among the high‐yielding cultivars used as parents for hybridization in breeding programs. There is evidence that the allelic diversity in Runner‐type peanut has significantly increased over the years and the diversity in Virginia type fluctuated greatly over the years (Milla‐Lewis et al , ). Parents with diverse origins have a higher probability to produce superior progenies than those of similar ancestry, but it has become increasingly difficult to find high‐yielding genotypes that do not have common parentage.…”

SSR Allelic Diversity Shifts in Zoysiagrass (Zoysia spp.) Cultivars Released from 1910 to 2016

“…Simple sequence repeats are particularly useful because they are polymerase chain reaction (PCR)‐based, have high levels of polymorphisms, and are codominant and multiallelic (Russell et al, 1997; Cai et al, 2005). Simple sequence repeats have been useful for estimating genetic diversity levels and how they have changed over time in a large number of species including: maize ( Zea mays L.; Lu and Bernardo, 2001), wheat ( Triticum aestivum L.; Roussel et al, 2005; Donini et al, 2000; Fu et al, 2003, 2006), timothy ( Phleum pratense L.; Tanhuanpää and Manninen, 2012), barley ( Hordeum vulgare L.; Malysheva‐Otto et al, 2007), oat ( Avena sativa L.; Fu et al, 2003), and peanut ( Arachis hypogaea L.; Milla‐Lewis et al, 2010a, 2010b).…”