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Genetic Diversity and Differentiation of Eleven Medicago Species from Campania Region Revealed by Nuclear and Chloroplast Microsatellites Markers.

ABSTRACT: The species belonging to the genus Medicago are considered a very important genetic resource at global level both for planet's food security and for sustainable rangelands management. The checklist of the Italian flora (2021) includes a total number of 40 Medicago species for Italy, and 27 for Campania region, with a number of doubtful records or related to species no more found in the wild. In this study, 10 Medicago species native to Campania region, and one archaeophyte (M. sativa), identified by means of morphological diagnostic characters, were analyzed in a blind test to assay the efficacy of nine microsatellite markers (five cp-SSRs and four n-SSRs). A total number of 33 individuals from 6 locations were sampled and genotyped. All markers were polymorphic, 40 alleles were obtained with n-SSRs ranging from 8-12 alleles per locus with an average of 10 alleles per marker, PIC values ranged from 0.672 to 0.847, and the most polymorphic SSR was MTIC 564. The cp-SSRs markers were highly polymorphic too; PIC values ranged from 0.644 to 0.891 with an average of 0.776, the most polymorphic cp-SSR was CCMP10. 56 alleles were obtained with cp-SSRs ranging from 7 to 17 alleles per locus with an average of 11. AMOVA analysis with n-SSR markers highlighted a great level of genetic differentiation among the 11 species, with a statistically significant fixation index (F_ST). UPGMA clustering and Bayesian-based population structure analysis assigned these 11 species to two main clusters, but the distribution of species within clusters was not the same for the two analyses. In conclusion, our results demonstrated that the combination of the used SSRs well distinguished the 11 Medicago species. Moreover, our results demonstrated that the use of a limited number of SSRs might be considered for further genetic studies on other Medicago species.

SUBMITTER: Djedid IK

PROVIDER: S-EPMC8774365 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:Background and aimsFew studies have evaluated the genetic structure and evolutionary history of wild varieties of important crop species. The wild papaya (Carica papaya) is a key element of early successional tropical and sub-tropical forests in Mexico, and constitutes the genetic reservoir for evolutionary potential of the species. In this study we aimed to determine how diverse and structured is the genetic variability of wild populations of C. papaya in Northern Mesoamerica. Moreover, we assessed if genetic structure and evolutionary history coincide with hypothetized (1) pre-Pleistocene events (Isthmus of Tehuantepec sinking), (2) Pleistocene refugia or (3) recent patterns.MethodsWe used six nuclear and two chloroplast (cp) DNA markers to assess the genetic diversity and phylogeographical structure of 19 wild populations of C. papaya in its natural distribution in Northern Mesoamerica.Key resultsWe found high genetic diversity (Ho = 0·681 for nuclear markers, and h = 0·701 for cpDNA markers) and gene flow between populations of C. papaya (migration r up to 420 km). A lack of phylogeographical structure was found with the cpDNA markers (NST < GST), whereas a recent population structure was inferred with the nuclear markers. Evidence indicates that pre-Pleistocene events or refugia did not play an important role in the genetic structuring of wild papaya.ConclusionsBecause of its life history characteristics and lack of an ancient phylogeographical structure found with the cpDNA markers, we suggest that C. papaya was dispersed throughout the lowland rain forests of Mexico (along the coastal plains and foothills of Sierras). This scenario supports the hypothesis that tropical forests in Northern Mesoamerica did not experience important climate fluctuations during the Pleistocene, and that the life history of C. papaya could have promoted long-distance dispersal and rapid colonization of lowland rainforests. Moreover, the results obtained with the nuclear markers suggest recent human disturbances. The fragmentation of tropical habitats in Northern Mesoamerica appears to be the main driver of genetic structuring, and the major threat to the dispersion and survival of the species in the wild.

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Genetic Diversity and Differentiation of Eleven Medicago Species from Campania Region Revealed by Nuclear and Chloroplast Microsatellites Markers.

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