Characterization of oxylipins and dioxygenase genes in the asexual fungus Aspergillus niger.
BACKGROUND
Aspergillus niger is an ascomycetous fungus that is known to reproduce through asexual spores, only. Interestingly, recent genome analysis of A. niger has revealed the presence of a full complement of functional genes related to sexual reproduction 1. An example of such genes are the dioxygenase genes which in Aspergillus nidulans, have been shown to be connected to oxylipin production and regulation of both sexual and asexual sporulation 234. Nevertheless, the presence of sex related genes alone does not confirm sexual sporulation in A. niger.


RESULTS
The current study shows experimentally that A. niger produces the oxylipins 8,11-dihydroxy octadecadienoic acid (8,11-diHOD), 5,8-dihydroxy octadecadienoic acid (5,8-diHOD), lactonized 5,8-diHOD, 8-hydroxy octadecadienoic acid (8-HOD), 10-hydroxy octadecadienoic acid (10-HOD), small amounts of 8-hydroxy octadecamonoenoic acid (8-HOM), 9-hydroxy octadecadienoic acid (9-HOD) and 13-hydroxy octadecadienoic acid (13-HOD). Importantly, this study shows that the A. niger genome contains three putative dioxygenase genes, ppoA, ppoC and ppoD. Expression analysis confirmed that all three genes are indeed expressed under the conditions tested.


CONCLUSIONS
A. niger produces the same oxylipins and has similar dioxygenase genes as A. nidulans. Their presence could point towards the existence of sexual reproduction in A. niger or a broader role for the gene products in physiology, than just sexual development.
Wadman
Mayken W
MW
Bioorganic Chemistry, Utrecht University, 3584 CH, Utrecht, the Netherlands. m.w.wadman@uu.nl
de Vries
Ronald P
RP
Kalkhove
Stefanie I C
SI
Veldink
Gerrit A
GA
Vliegenthart
Johannes F G
JF
D000595:Amino Acid Sequence; D001234:Aspergillus niger / Q000737:chemistry / Q000201:enzymology / Q000235:genetics; D002851:Chromatography, High Pressure Liquid; D049308:Dioxygenases / Q000235:genetics*; D008401:Gas Chromatography-Mass Spectrometry; D008969:Molecular Sequence Data; D020411:Oligonucleotide Array Sequence Analysis; D054883:Oxylipins / Q000737:chemistry*; D012100:Reproduction, Asexual; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid
D054883:Oxylipins; D049308:Dioxygenases