Abstract
Brassica incana is a secondary-gene pool wild relative of Brassica oleracea. Twenty-two B. incana populations are recorded in Italy, where the species has recently been pointed out as in priority need of conservation. While data on the spatial and temporal variation of B. incana Italian populations are completely lacking, this information is useful in conservation planning for this species. Three populations from the Sorrento peninsula and from the islands of Ischia and Capri, collected in 1984 and 2012, were characterised for 12 morpho-phenological and 21 genetic traits to assess their spatial–temporal variation. The populations were quite different for morpho-phenological and genetic traits. Spatial differentiation was high and easily explained by the isolation. Temporal differentiation between the Sorrento and Ischia populations was high and explained by a reduction in the population census across time, while it was not significant between the two Capri accessions as such pointing to a major effect of genetic drift. Numerical dimension is extremely relevant in evaluating conservation priorities since it has a major impact on population dynamics over time. The Sorrento and Ischia populations are under threat and urgently need conservation actions, suggesting an alarming scenario for the survival of other crop wild relative populations which are similar in census. Our data also show that, in an allogamous and self-incompatible species like B. incana, populations of 100–200 individuals maintain high allelic diversity. According to obtained results, natural populations of species with similar reproductive system and census can be considered at low risk of genetic erosion.
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Acknowledgements
S. Ciancaleoni and L. Raggi contributed equally to this work and must be both considered first authors. This research was partially funded by Fondo Ricerca di Base 2015, Università degli Studi di Perugia, “Analisi spazio-temporale dei cambiamenti genetici e valutazione agronomica e morfo-fisiologica in moltiplicazioni di una varietà sintetica e in linee inbred di Brassica oleracea L.” and by the European Community’s Seventh Framework Programme (FP/2007-2013) under the Grant Agreement No. 266394 “PGR Secure”. Thanks are due to Prof. Roberto Venanzoni (Università degli Studi di Perugia) and Dr. Lorenzo Panella for their help in collecting B. incana wild populations in 2012. The English editing has been done by Miriam Drissi.
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Online Resource 1. Crop wild relatives of Brassica genus present in Italy.
Online Resource 2. Collection sites of the Brassica incana wild populations.
Online Resource 3. SSR markers. Bibliographic reference codes, genebank entry, primer sequences, repeated motif, linkage group (LG), band range (in base pairs) relative to the 21 microsatellites used.
Online Resource 4. SSR markers. Weight of the different traits in PC1 and PC2.
Online Resource 5. Mixed model one-way ANOVA of the 12 traits recorded on the 2 populations from Sorrento (A), Ischia (B) and Capri (C).
Online Resource 6. Percentage of membership (q) of each Brassica incana individual to the three STRUCTURE groups.
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Ciancaleoni, S., Raggi, L. & Negri, V. Assessment of spatial–temporal variation in natural populations of Brassica incana in south Italy: implications for conservation. Plant Syst Evol 304, 731–745 (2018). https://doi.org/10.1007/s00606-018-1505-4
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DOI: https://doi.org/10.1007/s00606-018-1505-4