A novel strain of Pseudomonas inhibits Colletotrichum gloeosporioides and Fusarium oxysporum infections and promotes germination of coffee

This study aimed to screen phytobeneficial Pseudomonas sp. from the rhizosphere of Coffea arabica L. capable of antagonizing Colletotrichum gloeosporioids (Penzig) Sacco and Fusarium oxysporum Schlecht. A total of 40 Pseudomonas were isolated and checked for their antagonistic activity by dual culture techniques. The isolate named as PT11 showed maximum inhibition of Colletotrichum gloeosporioids (70%) and Fusarium oxysporum (72%) (P<0.05). PT11 was functionally characterized for its direct and indirect plant growth-promoting activities. PT11 showed a positive test for the production of phytohormones (IAA and GA3), zinc solubilization, siderophores production, and lytic enzymes. Treatment of Coffea arabica L. seeds with PT11 increased germination, reduced disease incidence due to infection of the fungal pathogen, and increased activities of defense-related enzymes. Based on the 16s rRNA gene sequence analysis, chemotaxonomic identification, phylogenetic analysis and biochemical characteristics, the bacterium PT11 showed the highest similarity with Pseudomonas putida group. Pseudomonas PT11 is capable of controlling pathogenesis of Colletotrichum gloeosporioids and Fusarium oxysporum through direct antagonism and boosting host immunity through ISR. Furthermore, Pseudomonas PT11 can be used to improve coffee germination.