Conserving Alfalfa Wild Relatives: Is Past Introgression with Russian Varieties Evident Today?

Abstract

Central Asia, particularly Kazakhstan, supports a rich concentration of wild alfalfa (Medicago sativa L.) relatives. Because tetraploid wild alfalfa freely crosses with domesticated alfalfa, they are important genetic resources. When identifying in situ populations to conserve, contamination of wild populations with domesticated alleles is an important consideration. We evaluated population structure and introgression between six wild populations of M. sativa nothossp. varia collected in northwestern Kazakhstan and five traditional Russian cultivars historically grown in the same region using two amplified fragment length polymorphism primer pairs and six simple sequence repeat loci. We found no difference between the Russian cultivars and wild populations for number of alleles or percentage polymorphic loci; however, gene diversity was less in the wild than in the cultivated populations. Cluster analysis and principle component analysis showed clear separation between wild and cultivated populations. Genetic differentiation among the cultivars was less than among the wild populations. Using a Bayesian approach, we found limited evidence of admixture among the wild and cultivated forms, although more admixture was evident in wild populations collected in less‐remote areas. On the basis of marker data, we concluded that three of the six wild populations stood out as candidates for in situ conservation given their uniqueness and lack of admixture with cultivated forms.

Stratification and population structure of the genetic resources of ancient medicinal rice (Oryza sativa L.) landrace Njavara

“…These data point to a recent episode of gene introgression into some of the Njavara accessions from other traditional rices grown sympatrically and the local spread of the introgressants. Introgressants showing varying levels of morpho-molecular discordance between themselves and with their parental lines have been reported in many other plant species (Lihová et al 2007;Greene et al 2008). The observed longer crop duration in all morphotype IV accessions substantiates such introgression.…”

Applied Genetics and Genomics in Alfalfa Breeding

“…Tetraploid falcata origins appear to be more complex, with some evidence of introgression from M. prostrata [13]. Mixing between cultivated and wild populations has been documented [16], but some wild populations appear to have remained distinct despite cultivars being grown in the vicinity [17].…”

Islands as refugia of Trifolium repens genetic diversity

“…With no direct management of T. repens genetic diversity it is unlikely that this will continue. Widespread use of cultivated forms in outbreeding species that are closely genetically related to forms found in other parts of the country highlights the difficulties faced when defining conservation areas (Greene et al 2008). In terms of conservation strategy, the authors would suggest that where native species commonly occur in close proximity to a con-specific crop, priority conservation sites for genetic diversity should be allocated to areas where little or no cultivation has occurred and may not in the future.…”