The isoprenoid pathway in the ectomycorrhizal fungus Tuber borchii Vittad.: cloning and characterisation of the tbhmgr, tbfpps and tbsqs genes.
The isoprenoid pathway of the ectomycorrhizal fungus Tuber borchii Vittad is investigated to better understand the molecular mechanisms at work, in particular during the maturation of the complex ascomata (the so-called "truffles"). Three T. borchii genes coding for the most important regulatory enzymes of the isoprenoid biosynthesis, 3-hydroxy-3-methylglutaryl-CoA reductase, farnesyl-diphosphate synthase (FPPS) and squalene synthase (SQS), were cloned and characterised. The analyses of their nucleotide and deduced amino acid sequences led us to identify the typical domains shown in homologous proteins. By using a quantitative real-time PCR the expression pattern of the three genes was analysed in the vegetative phase and during the complex ascoma maturation process, revealing an over-expression in the mature ascomata. The enzymatic activity of the T. borchii 3-hydroxy-3-methylglutaril-CoA reductase (HMGR) was investigated with a HPLC method, confirming that the significant isoprenoid biosynthesis in ripe ascomata proceeds not only via a transcriptional activation, but also via an enzyme activity control. These findings imply that isoprenoids play a fundamental role in Tuber ascomata, particularly in the last phases of their maturation, when they could be involved in antifungal or/and antimicrobial processes and contribute to the famous flavour of the truffle ascomata.
Guidi
C
C
Istituto di Chimica Biologica "G. Fornaini", Università degli Studi di Urbino "Carlo Bo", via Saffi 2, 61209, Urbino (PU), Italy.
Zeppa
S
S
Annibalini
G
G
Pierleoni
R
R
Guescini
M
M
Buffalini
M
M
Zambonelli
A
A
Stocchi
V
V
D000595:Amino Acid Sequence; D001203:Ascomycota / Q000235:genetics* / Q000378:metabolism; D001483:Base Sequence; D015139:Blotting, Southern; D003001:Cloning, Molecular; D013186:Farnesyl-Diphosphate Farnesyltransferase / Q000235:genetics* / Q000378:metabolism; D020869:Gene Expression Profiling; D005800:Genes, Fungal; D051228:Geranyltranstransferase / Q000235:genetics* / Q000378:metabolism; D006903:Hydroxymethylglutaryl CoA Reductases / Q000235:genetics* / Q000378:metabolism; D008969:Molecular Sequence Data; D038821:Mycorrhizae / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D015398:Signal Transduction / Q000235:genetics; D013729:Terpenes / Q000378:metabolism*
D013729:Terpenes; D006903:Hydroxymethylglutaryl CoA Reductases; D051228:Geranyltranstransferase; D013186:Farnesyl-Diphosphate Farnesyltransferase