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Meiotic drive is widespread in nature. The conflict it generates is expected to be an important motor for evolutionary change and innovation. In this study, we investigated the genomic consequences of two large multi-gene meiotic drive elements, Sk-2 and Sk-3, found in the filamentous ascomycete Neurospora intermedia. Using long-read sequencing, we generated the first complete and well-annotated genome assemblies of large, highly diverged, non-recombining regions associated with meiotic drive elements. Phylogenetic analysis shows that, even though Sk-2 and Sk-3 are located in the same chromosomal region, they do not form sister clades, suggesting independent origins or at least a long evolutionary separation. We conclude that they have in a convergent manner accumulated similar patterns of tandem inversions and dense repeat clusters, presumably in response to similar needs to create linkage between genes causing drive and resistance.

Poly(β-L-malic acid) (PMA) is a natural biopolyester that has pharmaceutical applications and other potential uses. In this study, we examined PMA production by 56 strains of the fungus Aureobasidium pullulans representing genetically diverse phylogenetic clades. Thirty-six strains were isolated from various locations in Iceland and Thailand. All strains from Iceland belonged to a newly recognized clade 13, while strains from Thailand were distributed among 8 other clades, including a novel clade 14. Thirty of these isolates, along with 26 previously described strains, were examined for PMA production in medium containing 5% glucose. Most strains produced at least 4 g PMA/L, and several strains in clades 9, 11, and 13 made 9-11 g PMA/L. Strains also produced both pullulan and heavy oil, but PMA isolated by differential precipitation in ethanol exhibited up to 72% purity with no more than 12% contamination by pullulan. The molecular weight of PMA from A. pullulans ranged from 5.1 to 7.9 kDa. Results indicate that certain genetic groups of A. pullulans are promising for the production of PMA.

From a survey of more than 50 diverse strains of Aureobasidium pullulans, 21 produced extracellular heavy oils. Most oil producers fell into phylogenetic clades 8, 9, and 11. Oil colors ranged from bright yellow to malachite. More than half of the strains produced oil that was fluorescent. In medium containing 5% (w/v) sucrose, oil yields ranged from 0.5 to 6 g oil/l. Strain CU 43 reached stationary growth phase at day 4 while oil yields were maximal at day 6. CU 43 produced bright yellow, highly fluorescent oil that also was visible as intracellular droplets under fluorescent microscopy. Oil was surface active, suggesting that it functions as a biosurfactant. Oil from two strains (CU 43 and NRRL Y-12974) differentially inhibited mammalian cancer cell lines. MALDI-TOF MS spectra suggested that A. pullulans strains produce a family of related oil structures.