Home About us Contact
|
Home About us Contact | ||
|
|
||
Mating-type Locus (mating-type + locus)
Selected AbstractsGenetic structure of Mycosphaerella graminicola populations in IranPLANT PATHOLOGY, Issue 5 2010M. Abrinbana To provide insight into the genetic structure of Mycosphaerella graminicola populations in Iran, a total of 221 isolates were collected from naturally infected wheat fields of five major wheat-growing provinces and analysed using AFLP markers and mating-type loci. All populations showed intermediate to high genotypic diversity. In the Golestan and Ardabil populations two mating types were found at near-equal frequencies, whilst all populations were in gametic disequilibrium. Moreover, clonal haplotypes were identified in different sampling sites within a field in both the Khuzestan and Fars provinces, demonstrating that pycnidia are probably the primary source of inoculum. All five populations had low levels of gene diversity and had private bands. Low levels of gene flow and high genetic differentiation were observed among populations and different clustering methods revealed five genetically distinct groups in accordance with the sampling areas. The Golestan and East Azarbaijan populations were more genetically differentiated than the others. Random genetic drift, selection and geographic barriers may account for the differentiation of the populations. The results of this study indicate a population structure of M. graminicola in Iran contrasting to that of most other countries studied. [source] Dynamic linkage relationships to the mating-type locus in automictic fungi of the genus MicrobotryumJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 8 2010J. L. ABBATE Abstract Regions of the chromosomes determining mating compatibility in some fungi, including Microbotryum lychnidis-dioicae and Neurospora tetrasperma, exhibit suppressed recombination similar to sex chromosomes in plants and animals, and recent studies have sought to apply basic theories of sex chromosome evolution to fungi. A phylogeny of the MTL1 locus in Microbotryum indicates that it has become part of the nonrecombining regions of the mating-type chromosomes in multiple independent events, and that recombination may have been subsequently restored in some cases. This illustrates that fungal mating-type chromosomes can exhibit linkage relationship that are quite dynamic, adding to the list of similarities to animal or plant sex chromosomes. However, fungi such as M. lychnidis-dioicae and N. tetrasperma exhibit an automictic mating system, for which an alternate theoretical framework exists to explain the evolution of linkage with the mating-type locus. This study encourages further comparative studies among fungi to evaluate the role of mating systems in determining the evolution of fungal mating-type chromosomes. [source] Global analysis of siRNA-mediated transcriptional gene silencingBIOESSAYS, Issue 12 2005Harsh H. Kavi The RNAi machinery is not only involved with post-transcriptional degradation of messenger RNAs, but also used for targeting of chromatin changes associated with transcriptional silencing. Two recent papers determine the global patterns of gene expression and chromatin modifications produced by the RNAi machinery in fission yeast.(9, 10) The major sites include the outer centromere repeats, the mating-type locus and subtelomeric regions. By comparison, studies of Arabidopsis heterochromatin also implicate transposons as a major target for silencing. Analyses of siRNA libraries from Drosophila, nematodes and Arabidopsis indicate that major repeats at centromeres, telomeres and transposable elements are likely targets of RNAi. Also, intergenic regions are implicated as targets in Arabidopsis. BioEssays 27:1209,1212, 2005. © 2005 Wiley Periodicals, Inc. [source] | ||||||||||