Morphological and molecular characterization of Vicia faba and Phaseolus vulgaris seed-born fungal endophytes

Abstract

Background: Fungal endophytes are heterotrophic microorganisms that occur inside plant tissues, with some showing adverse effects against insects, nematodes and plant pathogens. Initiatives are underway at the International Center of Insect Physiology and Ecology (ICIPE) to use these endophytes as a novel strategy for control of Liriomyza leafminer. Objective: The objective of this study was therefore to search for fungal endophytes from the Liriomyza major host plants that could be used in the management of this invasive insect pest. Materials and Methods: Bioprospecting was undertaken to isolate fungal endophytes from Phaseolus vulgaris and Vicia faba seeds collected from different local and super markets in Kenya. Fungal endophytes were isolated through seeds surface sterilization and characterized using morphological and molecular techniques. Fungal occurrence was analyzed using analysis of variance while Chi-square tests were performed to compare the various endophytes species occurring in the two host seeds. Results: Five fungal isolates were isolated from both P. vulgaris and V. faba seeds with no significant differences in their occurrence. However, there was significant difference between the endophyte species occurring in V. faba compared to P. vulgaris seeds (p<0.0001). Isolated fungi included Beauveria bassiana, Phialemonium sp., Phanerochaete chrysosporium and Metarhizium anisopliae. Beauveria bassiana ICIPE 693 occurred in all the V. faba seeds (100%) but not in P. vulgaris seeds. Similarly, P. chrysosporium had 66.7% occurrence in V. faba but absent in P. vulgaris seeds. The prevalence of Phialemonium sp. (55%) was only recorded in P. vulgaris, while that of M. anisopliae was recorded in both P. vulgaris and V. faba seeds with 55.4 and 70.8% occurrence, respectively. Conclusion: Fungal endophyte species occurrence in V. faba differed from P. vulgaris seeds. The characterization of these bean seed-born endophytes will not only create awareness but also facilitate studies on the role of these fungi in pest management strategies. The outcome of this study will stimulate further studies on the possible roles of these fungi in inhibiting the growth of artificially inoculated endophytes, assessing their pathogenicity and virulence effects on different sucking arthropod pests and evaluating the nutritional value of the seeds containing these endophytes.