The detection of airborne fungal spore contaminants in ‘Bambinella’ orchards through conventional and molecular methods

Abstract

'Bambinella' is an endemic fruit to the Maltese Islands and is widely sought after both locally and internationally. Ubiquitous airborne fungal spores cause fruit disease and decay, mainly during post-harvest and storage phases. When given the opportunity, through mechanical fruit injury or during fruit ripening, fungi infect fruit causing a detrimental infection and possibly to those adjacent. Consequently, fungal pathogens are a major concern to local businesses and producers, which suffer from more fruit losses. This results in a diminished economical surplus to farmers and the agricultural sector. Since Bambinella can only be harvested during the summer months, increasing its shelf-life would have a direct economic impact. In a recent local study, known pome fruit fungi were detected on the 'Bambinella' skin. The project aimed to tackle this problem, by performing active air sampling from 'Bambinella' orchards in different geographical regions in Malta, for identification and quantification of disease-causing fungi. Culturable and Next Generation – Amplicon Target Sequencing (NG-ATS) methods were performed to identify the fungal pathogens of the 'Bambinella' fruit to genus and species level. The results confirmed that common fungal pathogens were present in the air and on the 'Bambinella' surface and mass. These included Cladosporium spp., Alternaria spp., Penicillium spp., Aspergillus spp. and Botrytis cinerea amongst others. The fungal diversity was especially highlighted by NG-ATS method. The detected fungi are known to cause a variety of pre- and post-harvest rots in apple and pear fruit, including blue rot, grey rot and black scab. Airborne fungal communities which colonise 'Bambinella' fruit are responsible for fruit’s development and maturation, preservation and quality.