Surveillance of Landraces’ Seed Health in South Italy and New Evidence on Crop Diseases

Abstract

During the last three years, more than 300 landraces belonging to different plant species have been the main focus of an Italian valorization research project (AgroBiodiversità Campana, ABC) aiming at analyzing, recovering, preserving, and collecting local biodiversity. In this context, phytosanitary investigation plays a key role in identifying potential threats to the preservation of healthy seeds in gene banks and the successful cultivation of landraces. The surveillance carried out in this study, in addition to highlighting the expected presence of common species-specific pathogens such as Ascochyta pisi in peas, Ascochyta fabae in broad beans, and Macrophomina phaseolina, Xanthomonas axonopodis pv. phaseoli, and Xanthomonas fuscans subsp. fuscans in beans, pointed to the presence of novel microorganisms never detected before in the seeds of some hosts (Apiospora arundinis in common beans or Sclerotinia sclerotiorum and Stemphylium vesicarium in broad beans). These novel seedborne pathogens were fully characterized by (i) studying their morphology, (ii) identifying them by molecular methods, and (iii) studying their impact on adult crop plants. For the first time, this study provides key information about three novel seedborne pathogens that can be used to correctly diagnose their presence in seed lots, helping prevent the outbreaks of new diseases in the field.

Leguminous Seedborne Pathogens: Seed Health and Sustainable Crop Management

“…In fact, Nicholson and coworkers demonstrated that seeds affected by S. sclerotiorum were flatter, smaller, and discolored, with decreased germination relative to healthy ones [ 118 ]. Seedborne infection with S. sclerotiorum was also observed in faba bean in Italy in 2022; the experimental infection of plants showed severe symptoms, ranging from leaf chlorosis to stem rot ( Figure 9 ) [ 119 ].…”

“…When inoculated on grown plants, they were able to produce necrotic lesions that worsened over several days [ 17 ]. Similarly, Apiospora arundinis was isolated from the seeds of common bean, and, when inoculated into plants, typical necrotic spots on the leaves confirmed its pathogenicity in the new host [ 119 ]. Moreover, pathogenic Sclerotinia sclerotiorum was isolated for the first time from the seeds of faba bean and was shown to be able to induce leaf chlorosis and severe stem rot when artificially inoculated [ 119 ].…”

“…Similarly, Apiospora arundinis was isolated from the seeds of common bean, and, when inoculated into plants, typical necrotic spots on the leaves confirmed its pathogenicity in the new host [ 119 ]. Moreover, pathogenic Sclerotinia sclerotiorum was isolated for the first time from the seeds of faba bean and was shown to be able to induce leaf chlorosis and severe stem rot when artificially inoculated [ 119 ]. In 2022, an infection of common bean caused by Curvularia verruculosa was reported in China, and the symptoms were described as leaf spots [ 222 ].…”

“… Symptoms of S. sclerotiorum on faba bean; ( a ) chlorosis on the leaves and ( b ) root rot. The image was uploaded by Dell’Olmo et al, 2022 [ 119 ]. …”