Construction of transcription factor gene deletion library of Aspergillus luchuensis.

We selected 96 genes of Aspergillus luchuensis for the construction of a transcription factor gene deletion library. Of these, we successfully deleted 93 genes using Agrobacterium-mediated transformation (AMT) of A. luchuensis RIB 2604 ΔligD strains. We obtained only heterokaryonic strains after deletions of adaB, anBH1, hacA, hapB, hsf1, metR, and sonC gene, and additionally, could not obtain deletion strains for genes abaA and mcmA. The deletion strains will be available through our website (https://www.nrib.go.jp).

Production of sesquiterpene-type phytoalexins by hairy roots of Hyoscyamus albus co-treated with cupper sulfate and methyl jasmonate.

The production of sesquiterpene-type phytoalexins with a vetispyradiene skeleton by Hyoscyamus albus hairy roots induced by methyl jasmonate (MeJA) was reported in a previous paper. The production pattern on co-treatment with cupper sulfate and MeJA (CuSO(4)-MeJA) showed a TLC profile differing from that on treatment with MeJA. Thus, we studied the production of phytoalexins on hairy root culture involving co-treatment with CuSO(4)-MeJA. In the experiment, many sesquiterpene-type phytoalexins with a vetispyradiene skeleton were isolated, most of which were different from the products reported in the previous paper. Here, we isolated four new phytoalexins (1-4) along with known compounds 5-10 from the culture medium of H. albus hairy roots co-treated with MeJA-CuSO(4). The structures of the new compounds (1-4) were determined as: (3R,4S,5R,7S,9R)-3-acetoxy-9-(2-methylpropionyloxy)solavetivone (1), (3R,4S,5R,7S,9R)-3-hydroxy-9-(3-methylbutanoyloxy)solavetivone (2), (3R,4S,5R,7S,9R)-3-acetoxy-9-(3-methyl-butanoyloxy)solavetivone (3), and (3R,4S,5R,7S,9R)-3-acetoxy-9-(3-methyl-2-butenoyloxy)-solavetivone (4) based on MS and NMR including 2D-NMR data. These findings indicated that the production of phytoalexins in H. albus hairy roots yielded different products based on treatment with different chemicals (CuSO(4), MeJA, and MeJA-CuSO(4)).

Aspergillus oryzae atfB encodes a transcription factor required for stress tolerance in conidia.

Using an Aspergillus oryzae EST database, we identified a gene encoding a transcription factor (atfB), which is a member of the ATF/CREB family. Expression of atfB was barely detectable during vegetative growth, but was readily detected during conidiation in solid-state culture. Microarray analyses showed that expression of many other genes, including catalase (catA), were downregulated in an atfB-disruptant. The expression of most of these genes was upregulated in the wild-type strain during the conidiation phase in solid-state culture, and the expression pattern was similar to that of atfB itself. In the absence of stress, e.g. heat-shock or hydrogen peroxide, the conidial germination ratios for the DeltaatfB strain and the wild-type strain were similar, but the stress tolerance of conidia carrying the DeltaatfB deletion was less than that of the wild-type conidia. CRE-like DNA motifs, which are bound by ATF/CREB proteins, were found in the promoters of most of the downregulated genes in the DeltaatfB strain. Thus, atfB appears to encode a transcription factor required for stress tolerance in conidia.

Genome sequencing and analysis of Aspergillus oryzae.

The genome of Aspergillus oryzae, a fungus important for the production of traditional fermented foods and beverages in Japan, has been sequenced. The ability to secrete large amounts of proteins and the development of a transformation system have facilitated the use of A. oryzae in modern biotechnology. Although both A. oryzae and Aspergillus flavus belong to the section Flavi of the subgenus Circumdati of Aspergillus, A. oryzae, unlike A. flavus, does not produce aflatoxin, and its long history of use in the food industry has proved its safety. Here we show that the 37-megabase (Mb) genome of A. oryzae contains 12,074 genes and is expanded by 7-9 Mb in comparison with the genomes of Aspergillus nidulans and Aspergillus fumigatus. Comparison of the three aspergilli species revealed the presence of syntenic blocks and A. oryzae-specific blocks (lacking synteny with A. nidulans and A. fumigatus) in a mosaic manner throughout the genome of A. oryzae. The blocks of A. oryzae-specific sequence are enriched for genes involved in metabolism, particularly those for the synthesis of secondary metabolites. Specific expansion of genes for secretory hydrolytic enzymes, amino acid metabolism and amino acid/sugar uptake transporters supports the idea that A. oryzae is an ideal microorganism for fermentation.

The eln3 gene involved in fruiting body morphogenesis of Coprinus cinereus encodes a putative membrane protein with a general glycosyltransferase domain.

We identified and characterized elongationless3 (eln3-1), a restriction enzyme-mediated integration (REMI) mutation affecting fruiting body morphogenesis in Coprinus cinereus. The mutant produces an aberrant fruiting body in which the stipe hardly elongates during fruiting body maturation. In the wild type, cylindrical stipe cells, elongation growth of which is responsible for stipe elongation, make side-by-side contact with one another and run parallel to the stipe axis, whereas in the mutant, the organization of the stipe tissue is disturbed and much space is produced between stipe cells. This disorganization of the stipe tissue, together with reduced elongation of the stipe cells, causes the mutant stipe short and bulgy. After a plasmid rescue, the eln3 gene was identified as a DNA fragment that complements the eln3-1 mutation. The eln3 ORF is predicted to encode a protein of 927 amino acids with a general glycosyltransferase domain and to be located in the plasma membrane. Transcription of the eln3 gene is specifically activated in rapidly elongating stipes. Possible involvement of the putative Eln3 enzyme in cell-to-cell connection is discussed.