Search

Mangrove endophytes have been widely studied for several years and Avicennia marina endophytic fungi is known for its remarkable activity against many plant pathogens. Tomato is an important food crop in Saudi Arabia but it is susceptible to fungal diseases.The control of these phytopathogens through fungicides and pesticides is temporary. Thus, this study is aimed to isolate mangrove plant i.e. Avicennia marina endophytic fungal antagonists, characterize their phylogenetic positions and determine their antagonistic activities against tomato fungal pathogens. This study isintended to find a suitable alternative method to control or limit the spread of tomato diseases by using endogenous fungi of mangroves. Ninety fungal pathogens were isolated from three tomato farms in different regions of Riyadh city, Saudi Arabia. In addition, 40 endophytic mangrove i.e. Avicennia marina fungi were isolated from the eastern and western mangrove stands of the Kingdom of Saudi Arabia using potato dextrose agar, Czapek dox broth and malt extract broth media. These fungal strains were phylogenetically classified into at least sixteen genera based on 18S rRNA gene sequencing analysis. The antagonistic strains were screened via a Dual Culture Plate Assay and filter paper disc method. This study showed that endophytic fungal isolates have an antagonistic effect on most tomato pathogenic fungi. Cladosporium sphaerospermum had the highest inhibition while Trichoderma asperellum showed least antagonism against Avicennia marina endophytic fungi. This study proved that endophytic fungi present in Avicennia marina can control many tomato pathogens and their respective diseases. This work also cleared many aspects regarding the use of Avicennia marina endophytic fungal strains as potential biocontrol agents. Also, the diversity observed by these endophytic fungal strains from different areas of Saudi Arabia opened many doors for future research in the control of fungal pathogens. [ABSTRACT FROM AUTHOR]

Rice is a staple food consumed across the world and its purity is essential to manage human health. However, fungal mycotoxins are one of the real challenges for maintaining the purity of rice intended for human consumption. The present study was designed to detect the fungal isolates present in the imported rice cultivars obtained from the local markets of the Kingdom of Saudi Arabia and the mycotoxins they produce using molecular approaches. The morphological analysis and PCR-based sequencing of ITS-rDNA specify that the isolates in the contaminated rice belonged to Aspergillus and Penicillium genera. The phylogenetic analysis based on sequences of ITS-rDNA regions of the isolates confirmed that the Aspergillus isolates were homological to A. flavus and A. nidulans. Whereas, the Penicillium isolates were homological to P. commune and P. chrysogenum. The identification of mycotoxins using LC-MS revealed that the isolates of the genus Aspergillus produced aflatoxin and ochratoxin. The isolates of Penicillium genus produced citreoviridin and citrinin. The levels of mycotoxins varied among each variety of the rice samples tested in total. Ochratoxin was produced at the least concentration (184.7 µg/kg) in the contaminated samples. Citrinin (23170.5 µg/kg) was produced at higher volumes in comparison to other mycotoxins. These levels of mycotoxin contamination are alarming and raise significant queries regarding the purity of the imported rice grains throughout the period of harvest and storage. Therefore, the development of practical control is required for consumer safety. [ABSTRACT FROM AUTHOR]