Preserving Biodiversity in Marginal Rural Areas: Assessment of Morphological and Genetic Variability of a Sicilian Common Bean Germplasm Collection

Abstract

The historical cultivation of common bean (Phaseolus vulgaris L.) has resulted in the development of local populations/cultivars in restricted Italian rural areas. Many common bean landraces, still cultivated in small mountain areas from Sicily, have become outdated and endangered due to the commercial varieties spreading. These accessions are poorly known but often represent a genetic heritage to be preserved and enhanced. The ex situ conservation of fifty-seven Sicilian common bean landraces was carried out at the “Living Plants Germplasm Bank” at Ucria (Messina, Italy), founded by the Nebrodi Regional Park, together with the “Sicilian Plant Germplasm Repository” of University of Palermo (SPGR/PA). To assess the germplasm genetic diversity, nineteen morphological traits and eight Simple Sequence Repeats (SSRs) were used. Genetic distances among landraces were calculated to construct a clustering tree by using unweighted pair group method arithmetic (UPGMA). Seed germplasm diversity of Sicilian common bean varied from 80.7% to 93.3%, based on six seed descriptors and six leaf, flower, and pod descriptors, respectively, while cluster genetic analysis depicted a clear separation among all the 57 landraces. Principal coordinates (PCoA) and STRUCTURE analyses showed a prevalent rate of admixture between Mesoamerican and Andean gene pools in Sicilian common bean collection, confirming its heterogeneity. The observed high level of diversity evidenced the needs to adopt accurate criterion to plan a definitive ex situ germplasm collection to share agrobiodiversity with local farmers and to avoid any further loss of genetic resources in rural and protected areas.

Genetic Diversity and Population Structure of Common Bean (Phaseolus vulgaris L.) Landraces in the Lazio Region of Italy

“…The evaluation of molecular diversity using 12 SSR markers allowed us to detect in our collection a total of 75 alleles with a mean of 6.3 alleles per locus, a higher value than those discovered in the P. vulgaris germplasm from Sardinia [ 39 ] and Calabria [ 42 ], and not so different from those reported in other Italian collections [ 27 , 40 , 41 , 44 ]. Furthermore, the mean of He across the 12 SSR loci was higher (0.622) than those observed in other studies carried out on Italian [ 27 , 39 , 40 , 41 , 42 ] as well as European collections [ 28 , 29 , 30 ], highlighting the high level of genetic diversity present in the common bean germplasm in the Lazio region.…”

“…In Italy, common bean cultivation has been a traditional component of rural economies, particularly in mountainous and hilly areas along the Apennine ridge of the southern and central regions, where a wide diversity of bean landraces has been grown for generations [ 37 , 38 ]. The germplasm from several Italian regions such as Sardinia, Campania, Calabria, and Sicily has been characterized using morphological traits and biochemical and molecular markers [ 39 , 40 , 41 , 42 , 43 , 44 ]. However, these studies aimed to mainly evaluate the genetic relationships between accessions; hence, sampling was not exhaustive because it was limited to a single plant per landrace.…”

Factors Influencing the Emergence of Heterogeneous Populations of Common Bean (Phaseolus vulgaris L.) and Their Potential for Intercropping

“…In China and Brazil, the Mesoamerican type predominates, while in Africa, both types are equally represented, although they differ from country to country. In Europe, the Andean type predominates, but both types have been introduced [ 3 , 4 , 5 , 7 , 17 , 22 ]. Mesoamerican beans arrived through Spanish and Portuguese discoveries and were introduced first.…”

Morpho-Agronomic Genetic Diversity in Common Bean Landraces Based on Blup Values

“…The genetic diversity for morpho-agronomic traits in common bean landraces has been studied by some authors (Stoilova et al, 2013;Nadeem et al, 2020;Nogueira et al, 2021) through several multivariate methods, such as discriminant analysis, principal components and cluster analysis (Diniz Filho, 2000;Cruz et al, 2020). There are other studies, based on morphological and molecular information, that combine these methods with the heat map (Fiore et al, 2020;Androcioli et al, 2020;Laskar et al, 2021;Mecha et al, 2022), however, the tool is still little explored in the study of genetic divergence for morphological traits, and very little for the study of pairwise distances. In the context of mixed models, the evaluation of genotypes based on the REML/BLUP (Restricted Maximum Likelihood/Best Linear Unbiased Prediction) is an optimal procedure for more accurate estimates and predictions of genetic parameters and genotypic values that maximize selective precision, respectively (Resende, 2016).…”