TitleFusarium diversity and the role of endophytic fusarium and bacteria on diesease resistance in lilium longilflorum
NameRajmohan, Nimmi (author), Gianfagna, Thomas J (chair), Zhang, Ning (internal member), White, James (internal member), Hebbar, Prakash (outside member), Rutgers University, Graduate School - New Brunswick,
Easter lily--Diseases and pests--New Jersey,
Easter lily--Diseases and pests--Oregon,
DescriptionLilium longiflorum, is a horticultural crop which forms an important component of the cut flower ($67 million) and potted plant ($27 million) market in the United States. It is vulnerable to fungal disease, particularly caused by Fusarium sp. In this study Fusarium species associated with L. longiflorum (Easter lily) grown in New Jersey (NJ) were compared to the Fusarium isolates from Easter lilies grown in Oregon (OR). The aim of this work was to expand the knowledge of Fusarium species associated with Easter lilies by morphological and molecular characterization. Special emphasis is placed on the Gibberella fujikuroi species complex (GFSC) isolates of F. concentricum and F. proliferatum, isolated from this host for the first time. They were characterized by their mating types and mating population, as well as their in vitro toxin production. There have been no studies of these biological species in Easter lilies. Fusarium isolates were collected not only from diseased bulbs, but asymptomatic bulbs as well as from the soil in which it was grown.GFSC isolates were identified only from the NJ area and not from OR, which had F. solani and F. oxysporum in abundance. All the GFSC isolates were from asymptomatic bulbs and hence could be called endophytic. In the second part, two endophytic bacteria from healthy bulbs were isolated and identified as Bacillus sp. and Pseudomonas sp. by 16S rRNA gene sequencing. Phylogenetic analysis of unknown sequences along with sequences from GenBank and EMBL grouped the endophytic bacterial trains with Bacillus amyloliquefaciens and Pseudomonas fluorescens, respectively. This is the first report describing the association of such endophytic bacteria with this host. Microscopic studies revealed the intercellular location of the endophytic bacteria while the fungus was present in the outer epidermal layers. Dual plate assays and in vitro spore germination tests were carried out to determine the potential antagonistic activity of the bacteria towards pathogenic and non-pathogenic fungal isolates. Many isolates of Fusarium species were screened to characterize their pathogenicity. The non-pathogenic Fusarium species along with the endophytic bacteria were tested for disease control based on suppression of pathogen infection. Bacillus sp. was determined to be the best potential biocontrol agent followed by less pathogenic isolates of F. concentricum and F. oxysporum and then Pseudomonas sp. There is a significant potential for using these results in horticultural crop production.
NoteIncludes bibliographical references
Noteby Nimmi Rajmohan
CollectionGraduate School - New Brunswick Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.