Inferences from mitochondrial DNA patterns on the domestication history of alfalfa (Medicago sativa)

Abstract

To clarify the evolutionary history of alfalfa (Medicago sativa) wild-cultivated complex, we adopted a phylogeographical approach based on a characterization for Mitochondrial DNA variation through restriction fragment length polymorphisms of a sample of natural and cultivated populations. Twenty-two mitotypes were identified in the whole data set (155 individuals, one by population) with five probe/restriction enzymes (4).In the wild pool (M.s. ssp sativa 4x and M.s. sp coerulea 2x) from the presumed centre of origin (Near East to Central Asia), the diversity was high but the absence of geographic differentiation hinders a more precise location of the domestication.Within the cultivated alfalfa, the genetic differentiation associated with a geographic structure strongly suggests the existence of at least two independent routes of dissemination of alfalfa (East and West) from its center of origin. Namely, one original mitotype was detected in the cultivated pool from western Europe and North Africa. Its absence from the wild pool suggests an other wild source for the domesticated form, particularly for European ones (Flemish, Provence). This source could be the subspecies falcata which has been used in alfalfa breeding in the North of Europe; but recurrent gene flow in both directions between cultivated alfalfa and natural populations of ssp. falcata prevents any definitive conclusion.Finally, the Spanish wild populations (ref 1 to 4), located outside the presumed area of domestication, were shown to be highly original, with one abundant original mitotype. These wild populations could constitute an endemic wild pool present before alfalfa domestication and now partially introgressed by cultivated alfalfa.

Applied Genetics and Genomics in Alfalfa Breeding

“…Examination of mitochondrial, chloroplast, and nuclear genes and DNA markers clearly show that sativa is the tetraploid form of caerulea [13][14][15]. Although the data are generally consistent with recurrent polyploidization and interploidy gene flow, nuclear gene sequences also support the existence of a bottleneck in the domestication of at least some alfalfa populations [15].…”

ISSR and chloroplast DNA analyses indicate frequent hybridization of alien Medicago sativa subsp. sativa and native M. sativa subsp. falcata

“…sativa and subsp. varia (Muller et al 2003;Kaljund and Leht 2013). The lack of taxon-specific ISSR markers was addressed by sequencing three cpDNA regions in the second part of the study, and the results provide direct evidence for the hybrid origin of subsp.…”

“…The Medicago sativa-falcata complex is an attractive model system for studying infraspecific hybridization between alien domesticated taxa and their wild congeners (Quiros and Bauchan 1988;Muller et al 2003;Havananda et al 2011;Lapiņ a et al 2011;Kaljund and Leht 2013). This polymorphic species complex consists of several taxa that are diploid and/or tetraploid, including M. sativa subsp.…”

“…Thus, molecular evidence of natural hybridization between this alien and the native plant at the DNA level is scant. Using mitochondrial DNA (mtDNA) markers, Muller et al (2003) revealed that subsp. falcata and subsp.…”

RAPD polymorphism in the prebreeding material for cultivation of synthetic variations of lucerne (Medicago sativa L.)

“…The hybrids obtained in this way must be subjected to selection by the breeder through sowing seeds collected from the plants that have the highest seed yield and a high yield of green matter. Another method of improving plant yield is to select, on the basis of general combining ability and specific combining ability, those inbred lines that are most promising for creation of synthetic populations [5,[9][10][11][12]. Therefore, in breeding approaches which aim at developing new synthetic cultivars, a number of superior single plants must be collected through intermating in crossing blocks.…”