FIG. 2.

Induction of pseudohyphal growth in nitrogen limitation medium by sucrose requires cAMP-PKA-, MAP kinase-, and Snf1-mediated signaling. (A) Induction of pseudohyphal growth by 100 mM sucrose is deficient in mutants of the cAMP-PKA pathway, in a flo11Δ mutant, and in a mutant in which the gene encoding Tec1, a filamentation-specific transcription factor under the control of the MAP kinase pathway, was deleted. WT, wild type. (B) In a strain with HXK2 deleted, pseudohyphal growth was induced by 100 mM glucose to an extent similar to that with 100 mM sucrose. The presence of Gpr1 remained important for filamentation in the hxk2Δ/hxk2Δ mutant. (C) FLO11 expression level. Sucrose, maltose, and maltotriose are better inducers than glucose of FLO11 expression in a wild-type strain. Induction by sucrose, but not by maltose and maltotriose, was dependent on Gpr1. In a hxk2Δ/hxk2Δ mutant, all sugars induced the same relative level of FLO11 expression. Gene expression was monitored 4 h after induction with 100 mM of the indicated sugars by real-time quantitative PCR. Bars shaded progressively from black to white represent induction by glucose, sucrose, maltose, and maltotriose, respectively. The error bars indicate standard deviations. (D) Pseudohyphal growth induction by 100 mM glucose and sucrose was absent in a snf4Δ/snf4Δ mutant. The snf4Δ/snf4Δ mutant was grown for 48 h on sucrose.