Submitted to: Journal of Food Protection
Publication Type: Peer reviewed journal
Publication Acceptance Date: 9/30/2012
Publication Date: 10/1/2012
Citation: Pimenta, R., Moreira Da Silva, J., Buyer, J.S., Janisiewicz, W.J. 2012. Endophytic fungi from plums (Prunus domestica) and their antifungal activity against Monilinia fructicola. Journal of Food Protection. 75(10):1883-1889. Interpretive Summary: Microrganisms living inside plants without causing disease (endophytes) may play an important role in plant evolution, development, and resistance to various stresses caused by plant pathogens or the environment. We isolated endophytic fungi from plum leaves, identified, and evaluated them for production of antifungal compounds against fungus causing brown rot of stone fruits. A total of 163 fungi were isolated from 270 leaf samples from 30 plum trees representing 22 cultivars. The most frequently isolated species was Phaeosphaeria nodorum with 143 isolates constituting 86.5 percent of the total isolates. The remaining eight fungal species were isolated sporadically. Five fungi were not identified and may constitute new species. Four fungi of the most prominent fungus species produced volatile substances that were inhibitory to brown rot fungus. We identified these volatiles, and two of them, ethyl acetate and acetic acid, are well known fungal growth inhibitors. The role of isolates producing inhibitory volatiles which reduce diseases caused by brown rot fungus will be a subject of further investigation. This may lead to new approaches for disease control.
Technical Abstract: Plant endophytic microorganisms may play an important role in plant evolution, development, and resistance to biotic and abiotic stresses. However, the use of these microorganisms to benefit agriculture is in its infancy. We isolated endophytic fungi from plum leaves, identified them using ITS1 and ITS4 primers, and evaluated them for production of antifungal compounds against Monilinia fructicola, which causes brown rot of stone fruits, and Colletotrichum gloeosporioides, which causes anthracnose on a variety of fruit crops. A total of 163 fungi were recovered from 270 leaf samples taken from 30 plum trees representing 22 cultivars. The number of isolated endophytes per plant was 5.43, and 0.603 per sample. Twenty-nine morphotypes were detected but only 14 species were identified genetically. The most frequently isolated species was Phaeosphaeria nodorum with 143 isolates constituting 86.5 percent of the total isolates. The second most abundant species was Sordaria macrospora with only seven isolates (4.3 percent). Five isolates were not identified as their ITS nucleotide sequences did not match with any known sequences in the Genbank Database. Four isolates of P. nodorum produced volatiles inhibitory to M. fructicola. GC-MS analysis of volatiles produced by these isolates identified five volatiles: ethyl acetate, 3-methyl-1-butanol, acetic acid, 2-propyn-1-ol and 2-propenenitrile. Ethyl acetate and acetic acid are known growth inhibitors of a variety of fungal plant pathogens. The role of the isolates producing inhibitory volatiles in reducing diseases caused by M. fructicola is the subject of ongoing investigation.