Bioactivity of Endophytes from Calliandra calothyrsus, Leucaena diversifolia and Sesbania sesban Against Cercospora zeae-maydis

Abstract

Endophytes are microorganisms that accomplish parts of their life cycle within living host tissues without causing apparent damage to the plants. Endophytes confer survival advantage to the plant as they play a role in plant resistance to diseases. Cercospora zeae-maydis is a fungus that causes grey leaf spot disease of maize and is responsible for over 60%yield loss. Current chemical methods for control of the disease have adverse effects on human health and environment. Little is known on the potential of endophytes of Calliandra calothyrsus, Leucaena diversifolia and Sesbania sesban as biological control of Cercospora zeae-maydis. The objective of this study was to investigate the antagonistic potential of bacterial and fungal endophytes of the three plants against Cercospora zeae-maydis. A total of 75 endophytes were isolated from the three plant species based on morphological differences on PDA and NA media. Fungal and bacterial isolates were coded based on the plant part and plant species of origin such as FLC - for fungi isolated from the leaf of Calliandra calothyrsus, BLL-bacteria isolated from leaf of Leucaena diversifolia and BRS - for bacteria isolated from the root of Sesbania sesban. Thirty-three fungal and forty-two bacterial isolates were tested for antagonistic activity against Cercospora zeae-maydis by dual culture technique. Eleven fungal and twenty-four bacterial endophytes exhibited antagonistic activity against the pathogen. There were significant (p≤ 0.05) antagonistic activity among fungal and bacterial isolates against the pathogen. The highest inhibitory effects among the fungal isolates included FSC5 at 40%, FSC1at 37% and FSL3 at 30% respectively. The highest bacterial isolates activity was 72% for BLS3, 65 % for BRL2, 64 % for BRSI and60 %for BLC4.It is recommended that the endophytes from the three plants could serve as potential candidates for control of Cercospora zeaemaydis. Future studies should investigate on the bioactive molecules produced by these microorganisms