Loss of the L segment leads to a white colony of ascospores. (A) The genome stability of two different SAN strains (D2-SAN and D5-SAN) during vegetative growth was examined. The number of days post ascospore germination in a dextrose-containing malt extract agar (MEA) medium is indicated on the right. The Gene Expression Omnibus accession number is GSE-42359. (B) Southern blot analysis of the two D segments before and after RTU. The locations of the BsmBI restriction enzyme sites and the DNA probe used for Southern blot analysis are indicated in the right panel. The restriction fragments of the D segments in scaffold F and scaffold M are about 400 bp and 1,500 bp in length, respectively. The two parental haploid strains, CBS999.97(1-2, re) and CBS999.97(1-2, wt), were used as positive controls. (C) The organization and protein ID numbers of the nine annotated genes in the L segment. T. reesei polyketide synthase (tpks4) gene has been shown to be responsible for the formation of green conidia . (D) Loss of the L segment or tpks4 led to the white-conidia phenotype. Twenty hexadecads generated from sexual crossing of CBS999.97(1-2, wt) with D2-RTU or D5-RTU were dissected and isolated as described in Figure 1A. These 20 hexadecads all generated 16 ascospores. After germination, eight produced white conidia and the other eight produced green conidia. Shown are the conidia-color phenotype and genotyping data (by genomic PCR) of a representative hexadecad with 16 viable ascospores. (E) The aCGH results of four representative ascospores (numbers 1, 5, 9, and 16) in (D). The two white-conidia progeny (numbers 1 and 5) have no L segment, whereas the two green-conidia progeny (numbers 9 and 16) have the L segment.