A putative phospholipase C is involved in Pichia fermentans dimorphic transition.
BACKGROUND
Pichia fermentans DiSAABA 726 is a dimorphic yeast that reversibly shifts from yeast-like to pseudohyphal morphology. This yeast behaves as a promising antagonist of Monilia spp. in the yeast-like form, but becomes a destructive plant pathogen in the pseudohyphal form thus raising the problem of the biological risk associated with the use of dimorphic yeasts as microbial antagonists in the biocontrol of phytopathogenic fungi.


METHODS
Pichia fermentans DiSAABA 726 was grown in urea- and methionine-containing media in order to induce and separate yeast-like and pseudohyphal morphologies. Total RNA was extracted from yeast-like cells and pseudohyphae and retro-transcribed into cDNA. A rapid subtraction hybridization approach was utilized to obtain the cDNA sequences putatively over-expressed during growth on methionine-containing medium and involved in pseudohyphal transition.


RESULTS
Five genes that are over-expressed during yeast-like/pseudohyphal dimorphic transition were isolated. One of these, encoding a putative phospholipase C, is involved in P. fermentans filamentation. In fact, while the inhibition of phospholipase C, by means of 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphorylcholine (Et-18), is accompanied by a significant reduction of pseudohyphae formation in P. fermentans, the addition of exogenous cAMP fully restores pseudohyphal growth also in the presence of Et-18.


CONCLUSIONS
Phospholipase C is part of a putative "methionine sensing machinery" that activates cAMP-PKA signal transduction pathway and controls P. fermentans yeast-like/pseudohyphal dimorphic transition.


CONCLUSIONS
Phospholipase C is a promising molecular target for further investigations into the link between pseudohyphae formation and pathogenicity in P. fermentans.
Dipartimento di Agraria, Università degli Studi di Sassari, Viale Italia 39, 07100 Sassari, Italy.
Maria Lina
ML
Sanna
Giacomo
G
Zara
Severino
S
Zara
Quirico
Q
Migheli
Marilena
M
Budroni
Ilaria
I
Mannazzu
D003001:Cloning, Molecular; D004271:DNA, Fungal / Q000235:genetics; D018507:Gene Expression Regulation, Developmental; D015971:Gene Expression Regulation, Enzymologic; D015966:Gene Expression Regulation, Fungal; D015723:Gene Library; D025301:Hyphae / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D007091:Image Processing, Computer-Assisted; D010843:Pichia / Q000201:enzymology* / Q000235:genetics / Q000254:growth & development / Q000472:pathogenicity; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013382:Subtraction Technique; D010738:Type C Phospholipases / Q000235:genetics / Q000378:metabolism*
D004271:DNA, Fungal; D012333:RNA, Messenger; D010738:Type C Phospholipases
3′-5′-cyclic adenosine monophosphate (cAMP); Dimorphic shift; Phospholipase C; Pichia fermentans; Pseudohypha; Rapid subtraction hybridization (RaSH)