TY - JOUR
T1 - An extended physical map of the TOX2 locus of Cochliobolus carbonum required for biosynthesis of HC-toxin
AU - Ahn, Joong Hoon
AU - Cheng, Yi Qiang
AU - Walton, Jonathan D.
N1 - Funding Information:
This research was supported by the U.S. Department of Energy Division of Energy Biosciences and the U.S. Department of Agriculture Competitive Grants Research Program.
PY - 2002
Y1 - 2002
N2 - In genetic crosses, HC-toxin production in the filamentous fungus Cochliobolus carbonum appears to be controlled by a single locus, TOX2. At the molecular level, TOX2 is composed of at least seven duplicated and coregulated genes involved in HC-toxin biosynthesis, export, and regulation. All copies of four of the TOX2 genes were previously mapped within a 540-kb stretch of DNA in strain SB111. Subsequently, an additional three TOX2 genes, TOXE, TOXF, and TOXG, have been discovered. In this paper we have mapped all copies of the new genes, a total of seven, and show that except for one of the two copies of TOXE, which was previously shown to be on a chromosome of 0.7 Mb in strain SB111, they are all linked to the previously known TOX2 genes within ∼600 kb of each other on a chromosome of 3.5 Mb. We show here that this chromosome also contains at least one non-TOX2 gene, EXG2, which encodes an exo-β1,3-glucanase. EXG2 is still present in strains that have undergone spontaneous deletion of up to ∼1.4 Mb of the 3.5-Mb chromosome. The results contribute to our understanding of the complex organization of the genes involved in HC-toxin biosynthesis and are consistent with the hypothesis that a reciprocal chromosomal translocation accounts for the pattern of distribution of the TOX2 genes in different C. carbonum isolates.
AB - In genetic crosses, HC-toxin production in the filamentous fungus Cochliobolus carbonum appears to be controlled by a single locus, TOX2. At the molecular level, TOX2 is composed of at least seven duplicated and coregulated genes involved in HC-toxin biosynthesis, export, and regulation. All copies of four of the TOX2 genes were previously mapped within a 540-kb stretch of DNA in strain SB111. Subsequently, an additional three TOX2 genes, TOXE, TOXF, and TOXG, have been discovered. In this paper we have mapped all copies of the new genes, a total of seven, and show that except for one of the two copies of TOXE, which was previously shown to be on a chromosome of 0.7 Mb in strain SB111, they are all linked to the previously known TOX2 genes within ∼600 kb of each other on a chromosome of 3.5 Mb. We show here that this chromosome also contains at least one non-TOX2 gene, EXG2, which encodes an exo-β1,3-glucanase. EXG2 is still present in strains that have undergone spontaneous deletion of up to ∼1.4 Mb of the 3.5-Mb chromosome. The results contribute to our understanding of the complex organization of the genes involved in HC-toxin biosynthesis and are consistent with the hypothesis that a reciprocal chromosomal translocation accounts for the pattern of distribution of the TOX2 genes in different C. carbonum isolates.
KW - Cyclic peptide
KW - Gene cluster
KW - Host-selective toxin
KW - Plant pathogenesis
UR - http://www.scopus.com/inward/record.url?scp=0036352019&partnerID=8YFLogxK
U2 - 10.1006/fgbi.2001.1305
DO - 10.1006/fgbi.2001.1305
M3 - Article
C2 - 11860263
AN - SCOPUS:0036352019
SN - 1087-1845
VL - 35
SP - 31
EP - 38
JO - Fungal Genetics and Biology
JF - Fungal Genetics and Biology
IS - 1
ER -