TABLE CONTENTS

From Suppressive Soils to Suppressive Plants: The Role of Endophytes in
Plant Driven Management of Radopholus similis.
zum Felde, A. (1), R.A. Sikora (1) & L.E. Pocasangre. (2)
(1) Nematology in Soil Ecosystems, Department of Plant Pathology, Institute of Crop Science and Resource
Conservation (INRES), University of Bonn, Nussalle 9, D-53113 Bonn, Germany; (2) Bioversity International -
Bananas for Livelihoods c/o CATIE, Turrialba, 7170 Cartago, Costa Rica.
A number of nematode antagonistic fungi have been isolated from banana and plantain roots
and corms over the past two decades. Among them are a number of non-pathogenic Fusarium
oxysporum and Trichoderma atroviride isolates recovered in Guatemala and Costa Rica from
banana and plantain roots in soils identified as nematode suppressive. The identified inducing
agents of the observed suppression are nematode antagonistic endophytic fungi. Because the
designation of the soils as being suppressive is misleading, the term in-planta
suppressiveness was coined. In vivo screening tests with isolates from these fields identified
fungi that significantly reduced the number of Radopholus similis in roots between 72 and
85%. Re-isolation of inoculated fungi from roots confirmed the endophytic nature of the
fungi. Subsequent greenhouse and field studies have proven that by inoculating selected
endophytes onto tissue culture banana plants, nematode penetration and reproduction in these
plants is reduced and plant growth as well as yield is promoted. In other words, the plants
become resistant to nematode attack. Multiple inoculations of endophytes increase both
nematode control and plant growth promotion effects. Endophytic fungi that colonize plant
roots are perfectly placed to act as biological control agents of nematodes, as they are present
in the same tissues as those where nematode attack occurs. Conversely to mycorrhizal fungi,
which are also present in plant roots, the mutualistic endophytes isolated from banana, are not
obligate symbionts, and can therefore be produced in industrial fermentors. In addition, with
endophytes, there is no need for repeated soil inundative applications, as only the rhizoplane
of transplants is treated prior to field planting. Large scale inoculations of transplants have
already been successfully carried out. The results of long years of research demonstrate the
future potential of R. similis management through in-planta suppressive Musa plants.
5 th International Congress of Nematology, 2008 131