Global Survey of Canonical Aspergillus flavus G Protein-Coupled Receptors

a GPCR mutants were assayed for germination rate at 4 to 9 h postinoculation and for aflatoxin (AF) production on AF-promoting (YES) and AF-repressing (YEP) media. For both assays, shaded squares represent data points that were significantly different from those for the wild type (WT). The color of each box indicates the amount of germinated spores or AF produced as a percentage of WT germination or AF produced. The ratios of spores produced under light and dark conditions (L/D), as well as spores and sclerotia produced by high-density (H) and low-density (L) inocula, were determined, and any data point that did not exhibit the same pattern as the WT is shaded gray. For all four experiments, statistical significance was determined by a Student t test, with P < 0.05. Deletions are shown in the “Strain” column.

a Strains were grown on a variety of media with different sources of carbon and nitrogen. The radial growth was measured, and mutants were compared to the WT on the same medium. The carbon sources were glucose (Glu), galactose (Gal), xylose (Xyl), sucrose (Suc), corn oil, and corn oil with glucose. The nitrogen sources were peptone (Pep), ammonium chloride, and proline (Pro). Shaded boxes indicate data points that were significantly different from those for the WT, with the color representing the degree of growth inhibition compared to the WT. Significance was determined by a Student t test, with P < 0.05. Deletions are shown in the “Strain” column.

a Strains were exposed to a variety of stresses, including reactive oxygen species (ROS), cell wall stress, osmolarity stress, and high and low pHs. Percent inhibition of growth under stress versus growth on control medium (GMM) was measured. Shaded boxes indicate data points in which the percent inhibition of the mutant differed significantly from that of the WT, and the degree of the difference is indicated by the different colors. Darker red tones indicate mutants with greater sensitivity to the stressor, while darker blue tones denote the opposite. Significance was determined by a Student t test, with P < 0.05. Deletions are shown in the “Strain” column.

a Strains were incubated with or without MeJA, a repressor of AF biosynthesis, and AF was extracted and measured by HPLC. Strains were also exposed to disks soaked with the sporulation inducers 13(S)-HpODE and linoleic acid or the negative control ethanol (EtOH), and spores surrounding the disks were counted. Shaded boxes represent data points that did not exhibit the WT response, and the mutant response is indicated (“NR” means “no response”). Statistical significance was determined by a Student’s t test with P < 0.05. Deletions are shown in the “Strain” column.

a Expression data from several different studies were mined for expression levels of the GPCRs under various conditions. For each data set, the log₂-fold change (FC) value and P value (p val.) are reported. The first four data sets contain microarray data, while the last two contain RNA-seq data. The first data set (“Maize/mycelia”) reports the FC in expression from A. flavus grown as mycelia in liquid culture to A. flavus grown on maize. The second (“Wheat/maize”) reports the FC in expression from A. flavus growing on maize to A. flavus growing on wheat. The third (“Germ/endosperm”) reports the FC in expression from A. flavus growing on the corn kernel endosperm to growth on the kernel germ. The fifth and sixth data sets (“Mycelia/sclerotia”) report the FC in expression from A. flavus growing as mycelia to producing sclerotia. The final data set reports the FC in expression from untreated A. flavus cultures to those exposed to 5-AC.