Recovery, characterization and conservation of plant agrobiodiversity of Alto Medio Sannio inner area

Agrobiodiversity underpins ecological functions, sustainable development, food security and climate change resilience, contributing to the overall ecosystems’ health and human well-being. A key component of agrobiodiversity is represented by landraces, plant genetic resources adapted to restricted marginal rural environments and associated with a set of traditional cultural practices and knowledge, which constitute a gene pool of unexplored variability, useful for biodiversity enrichment, climate change mitigation and human health promotion. However, landraces are increasingly threatened with extinction by replacement with improved commercial cultivars released by the industrial agriculture system, therefore active conservation strategies are necessary to maintain these critical resources. The aim of this doctoral thesis was to identify possible development paths linked to the territory, to the agrobiodiversity and to the sustainability in the marginalized areas based on the recovery/preservation, characterization and valorisation of plant local resources. The inner area of “Alto Medio Sannio” was selected as case study planning different complementary and consecutive research activities. Firstly, a recovery activity of all typical legume landraces and of the associated traditional knowledge was conducted throughout the area of study. The collected local germplasm was stored ex situ in Molise Germplasm Bank and a comprehensive characterization activity – paper I, II and III − was performed on the most representative common bean (P. vulgaris L.) landraces. In detail, in the paper I (Falcione et al. 2022), a multi-level characterization approach allowed to explore the diversity among seven Italian common bean landrace populations (Ciliegino, San Michele Rosso, Monachella, Mascherino, Pinto, Tuvagliedda Rossa and Suocera e Nuora). Results of the work showed that populations were separated in two main groups of seed morpho-colorimetric features, while phaseolin characterization indicated that all the populations belong to Andean gene pool, displaying four typical Andean phaseolin isoforms. The ISSR molecular markers data provided important insights on the genetic variability and phylogenetic relationships among Italian common bean landrace populations, unveiling genetic similarities among “Alto Medio Sannio” common bean landraces and populations coming from Tuscany and Basilicata region. The frequent seed exchange practice occurring among farmers, following the transhumance pathways along the Apennine regions, could have influenced the genetic structure of the common bean populations. Results of the short-term salinity and osmotic stress response showed morphological and biochemical changes at organ level strictly related to the genotype and the stress typology, with a higher impact of salinity over osmotic stress, and allowed to identify common bean genotypes with marked “climate smart traits” (Monachella, Ciliegino and Tuvagliedda Rossa) due to increased amount of stress protective antioxidants (chlorophyll and carotenoids). Furthermore, experimental data reported a positive correlation between proline level and salinity stress sensitivity, suggesting the potential use of this osmolyte as a biochemical marker for a large-scale screening of salt sensitive bean landraces. In the paper II (Falcione et al. 2024), a complementary characterization approach allowed to identify three Italian common bean landrace populations (Ciliegino, San Michele Rosso and Fagiolo d’Acqua) as a valuable source of diversity and bioactive chemical features. Results of this study showed seed morphological, genetic and phaseolin diversity among the three common bean populations. NMR seed metabolomic profiles revealed the presence of a vast number of metabolites, ranging from amino acids, sugars, organic acids, nucleosides, and other miscellaneous compounds. Furthermore, the low levels of organic acids (lactic and pipecolic acid) found in Ciliegino seeds may have played a suppressive role in colon cancer cell proliferation, while the high levels of stress protective metabolites (citric acid, alanine, leucine and methionine) reported in San Michele Rosso may have contributed to counteract mid/long term salinity stress, both at seed and plant level. Data also showed that the stress mitigating compounds such as proline, sugars and carotenoids were not correlated with oxidative stress level (MDA) detected in leaf of all the three common bean populations, however, the structural reorganization in the main pigment protein complexes contributed to increase the photosynthesis efficiency of San Michele Rosso plants under salinity conditions. In paper III (in preparation), a MS-based metabolomics has been performed to deep investigate the seed metabolome of two Italian red common bean landrace populations, Ciliegino and San Michele Rosso, and one from Spain, Anguiano bean. The preliminary results indicated that the populations present distinct metabolomic profiles, being separated in three distinct groups in the PCA and PLS-DA, with a higher accumulation of specific chemical categories, such as organic acids in Ciliegino and Anguiano bean and flavonoids in San Michele Rosso. These molecules could act as potential biomarkers of populations’ distinctiveness and differentiation (metabolomic fingerprints). In a forward-looking vision of this work, the completion of the annotation process of the metabolite reference set will allow to define the chemical classes enriched in each genotype. Furthermore, a more in-depth analysis of these metabolites, in term of the corresponding biological significance and the possible involvement in the environmental stress tolerance, will enable to determine the local resources value in regard to nutritional, therapeutic and/or the abiotic/biotic stress resilience potential. Taken together, the data of this thesis enabled to recognize local landraces as a reservoir of diversity, stress adaptive traits and valuable bioactive compounds, with possible beneficial effects for human health and for facing the challenges of the increasing climate variability. The conducted experimental activity provided clear evidence for the establishment of adequate conservation strategies to preserve common bean landraces and for supporting the socio-economic revitalization of the marginalized inland rural areas where these local resources are confined − all in full accordance with some “place-based” strategies proposed by the public policy National Strategy for Inner Areas (Italian SNAI), which plans to promote territorial development and economic and social regeneration of these fragile Italian territories.