Genetic Diversity and Population Structure of Wild Beets (Beta spp.) from the Western Iberian Peninsula and the Azores and Madeira Islands

Maria Manuela Veloso,Maria Cristina Simões-Costa,Carla Marques Ribeiro,Maria Cristina Duarte,Cândido Pinto-Ricardo,Dalila Espírito-Santo,Joana Bagoin Guimarães,Octávio S Paulo,Isabel Evaristo

doi:10.3390/d13110593

Abstract

In this work, using simple sequence repeat (SSR) markers, we present new insights into the genetic diversity, differentiation, and structure of Beta vulgaris subsp. maritima of western Iberia and the Azores and Madeira islands and of B. macrocarpa from southern Portugal. B. macrocarpa occurs only in southern Portugal and frequently in sympatry with B. vulgaris subsp. maritima, showing genetic introgression. B. macrocarpa has a better-defined structure than B. vulgaris subsp. maritima, which has a high degree of admixture. A great differentiation (FST ranging from 0.277 to 0.184) was observed among the northern populations of B. vulgaris subsp. maritima. In contrast, only a small differentiation (FST ranging from 0.000 to 0.026) was detected among the southern B. vulgaris subsp. maritima populations. The inland B. vulgaris subsp. maritima populations (“RIO” and “VMT”) are distinct from each other, which also occurs with the two islands’ populations (“MAD” and “AZO”). The existence of two distinct Atlantic Sea currents can explain the fact that Madeira is related to the southern populations, while the Azores is related to the northern populations. We consider that understanding the relationships existing within Beta spp. is key to future genetic studies and for the establishment of conservation measures. Our results show that the southern coastal areas of Portugal should be considered as a potential site for in situ conservation of the beet wild relatives. Special attention is needed in what concerns B. macrocarpa because this is a rare species that also occurs in a sympatric relationship with B. vulgaris subsp. maritima.

Highlights

The genetic diversity of the wild beet populations was studied through a microsatellite analysis procedure similar to that one previously reported [8]
0.90 (SB07) (Table 1), indicating that the used loci displayed a high level of variability and are useful diversity indicators, and it is evident that the locus SB07 displayed the highest values of number of effective alleles (Ne), He and polymorphism information content (PIC), while the locus SB13 displayed the lowest values (Table 1)
A PCoA analysis of the overall populations explained 63.60% of the variation in the first two axes, 50.75% in the first coordinate, and 12.85% in the second coordinate

Summary

Introduction

The genus Beta (Amaranthaceae family) is native to Europe, North Africa, and adjacent areas of the East Atlantic Coast, from about 15◦ N (Cabo Verde Islands) to about 58◦ N (south of Norway and southern Sweden) and West Asia. Climatic changes contributed to establishing the Iberian Peninsula as a differentiation center and origin of the postglacial northward expansion of plants (e.g., Beta genus) [1,2]. Vulgaris (cultivated beets), and B. macrocarpa Guss. Sea beet is an outcrossing species and a typical coastal taxon of the Mediterranean basin [4], but it exists in more continental habitats [5,6,7,8]. B. macrocarpa is self-compatible and occurs in the Iberian Peninsula, North Africa, Canary Islands, and West Asia (Mediterranean basin) [10]

Results

Discussion

Conclusion