Effects of temperature and water activity on 25 de novo strains of pathogenic plant fungi in Al-Baha and Baljurashi cities in Saudi Arabia

Abstract

AbstractFungi inflict a great deal of damage to crops in fields and in storage facilities, causing issues such as leaf spot, wilt, rust, dieback and rot, as well as releasing mycotoxins that taint vegetation. In the current study, 25 de novo fungal isolates were taken from infected plant tissue (leaf, root and fruit), at pre- and post-harvest stages. Isolates were identified using molecular markers; 8 genera and 15 species were determined. The most common species was Penicillium spp. (40%), Aspergillus spp. (20%), Fusarium spp. (16%) and Alternaria alternata species (8%). The remaining 16% was comprised of various types of fungi, including Geotrichum candidum, Neofusicoccum parvum, Rhizopus stolonifera and Mucor fragilis. Many of these genera are known to cause significant crop damage and are notorious mycotoxin producers. An evaluation of the optimal growth temperature revealed the ideal temperatures were 30 °C for 56% of isolates, 25 °C for 28% of isolates and 20 °C for 16% of isolates. An assessment of water activity showed that 60% of isolates belonged to Penicillium and Aspergillus spp. and were mesophilic and xerophilic. Another 28% of isolates were Fusarium spp., Geotrichum candidum, Neofusicoccum parvum and Mucor fragilis, and hydrophilic. The remaining 12%, representing Alternaria alternata and Rhizopus stolonifera, were mesophilic. The current study provides accurate eco-physiological response data and molecular information for each isolate. The findings can assist the development of novel approaches to control the expansion of invasive fungal infections and minimise their deleterious consequences.