The evolution of LOL, the secondary metabolite gene cluster for insecticidal loline alkaloids in fungal endophytes of grasses.

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Title: The evolution of LOL, the secondary metabolite gene cluster for insecticidal loline alkaloids in fungal endophytes of grasses.
Author: Kutil, Brandi Lynn
Abstract: LOL is a novel secondary metabolite gene cluster associated with the production of loline alkaloids (saturated 1 -aminopyrrolizidine alkaloids with an oxygen bridge ) exclusively in closely related grass -endophyte species in the genera Epichlo ? and Neotyphodium . In this study I characterize the LOL cluster in E . festucae , including the presentation of sequence corresponding to 10 individual lol genes as well as defining the boundaries of the cluster and evaluation of the genomic DNA region flanking LOL in E . festucae . In addition to characterizing the LOL cluster in E . festucae , I present LOL sequence from two additional species , Neotyphodium coenophialum and Neotyphodium sp . PauTG -1 . Together with two recently published LOL clusters from N . uncinatum , these data allow for a powerful phylogenetic comparison of five clusters from four closely related species . There is a high degree of microsynteny (conserved gene order and orientation ) among the five LOL clusters , allowing us to predict potential transcriptional co -regulatory binding motifs in lol promoter regions . The relatedness of LOL clusters is especially interesting in light of the history of interspecific hybridizations that generated the asexual , Neotyphodium lineages . In fact , three of the clusters appear to have been introduced to different Neotyphodium species by the same ancestral Epichlo ? species , for which present day isolates are no longer able to produce lolines . To address the evolutionary origins of the cluster we have investigated the phylogenetic relationships of particular lol ORFs to their paralogous primary metabolism genes (and gene families ) from endophytes , other fungi and even other kingdoms . I present extensive evidence that at least two individual lol genes have evolved from primary metabolism genes within the fungal ancestors of endophytes , rather than being introduced via horizontal gene transfer . I also present complementation studies in Neurospora crassa exploring the functional divergence of one lol gene from its primary metabolism paralog . While it is clear that these insecticidal compounds should convey a selective advantage to the fungus and its host , thus explaining preservation of the trait , this analysis provides an exploration into the evolutionary origin and maintenance of the genes that comprise the LOL and the cluster itself .
URI: http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1122
Date: 2009-05-15

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The evolution of LOL, the secondary metabolite gene cluster for insecticidal loline alkaloids in fungal endophytes of grasses.. Available electronically from http : / /hdl .handle .net /1969 .1 /ETD -TAMU -1122 .

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