Identification of a mitotic recombination hotspot on chromosome III of the asexual fungus Aspergillus niger and its possible correlation elevated basal transcription

Abstract

Genetic recombination is an important tool in strain breeding in many organisms. We studied the possibilities of mitotic recombination in strain breeding of the asexual fungus Aspergillus niger. By identifying genes that complemented mapped auxotrophic mutations, the physical map was compared to the genetic map of chromosome III using the genome sequence. In a program to construct a chromosome III-specific marker strain by selecting mitotic crossing-over in diploids, a mitotic recombination hotspot was identified. Analysis of the mitotic recombination hotspot revealed some physical features, elevated basal transcription and a possible correlation with purine stretches.

Identification of a Classical Mutant in the Industrial HostAspergillus nigerby Systems Genetics: LaeA Is Required for Citric Acid Production and Regulates the Formation of Some Secondary Metabolites

“…Since the occurrence of mitotic recombination is low, a mitotic cross-over involving the SNPs on chromosome II in a 1.4-MB region probably occurred only in a single segregant (out of 78). To further narrow down the number of relevant SNPs, a larger pool of segregants or the use of chemicals such as neomycin or 5-azacytidine ( van de Vondervoort et al 2007 ) to induce mitotic recombination might be used. However, in view of the relatively low number of SNPs found in the D15 mutant (52 in total), we were left with only a few candidate genes.…”

Evolutionary genetics of nonself recognition regarding social and sexual interactions of fungi

“…Notably, these markers are near to, but not spanning, the centromere. This level of specificity has been previously reported to occur on chromosome 3 as well, in the 80 kb region between lysA and hisH (van de Vondervoort et al, 2007). Interestingly, we did not observe any crossovers at this location in the haploids, but one of the diploids did show loss of heterozygosity near this marker.…”

“…Traditionally, mitotic mapping in fungi has been performed with phenotypic markers, mostly various auxotrophies (Bos et al, 1988;Debets et al, 1993;van de Vondervoort et al, 2007). Here we use a genome-wide sequencing approach.…”

Development of a Homologous Transformation System forAspergillus aculeatusBased on thesCGene Encoding ATP-Sulfurylase

“…Although there is no element in Aspergilli known as an initiator increasing homologous recombination, like the chi (crossover hotspot instigator) sequence in E. coli, 12) it has been reported that there is a recombination hotspot in A. niger in the 80-kb region on chromosome III. 13) The initiation site of gene conversion events might lie on the sC locus in A. aculeatus, although the mechanisms increasing homologous recombination frequency need to be further analyzed. Now, we are performing a reporter assay of modified promoters of the cellulase gene to identify the ciselements sufficient for gene induction in response to an inducer using this transformation system.…”