Upon nutrient limitation, diploid cells of the yeast Saccharomyces cerevisiae
can undergo two distinct developmental responses. In the presence of a fermentable carbon source (e.g.
, dextrose or galactose), starvation induces a modified mitotic division that produces elongated daughter progeny termed pseudohyphae (PH) 
. Reiterated cell division under this PH program forms chains of elongated cells on solid agar, allowing yeast to forage for nutrients 
. In contrast, cells engage in meiotic development and sporulation if starved for nitrogen in the presence of a non-fermentable carbon source (e.g.
, acetate or glycerol). Under this program, the diploid genome is duplicated (2C to 4C) and then segregated into four haploid (1C) meiotic products encased in a spore wall. This spore structure protects haploid progeny until favorable nutrient conditions are available.
Recent findings suggest that the two developmental responses to nitrogen deprivation, PH development and meiotic sporulation, are not entirely separate pathways. First, cells that are returned to mitotic growth from meiotic prophase produce elongated buds, reminiscent of PH cells 
. Second, PH development and sporulation share a set of regulatory factors. Genes that are necessary for meiotic induction, IME1
nducer of Me
, respectively) 
, are also necessary for PH development and the subsequent formation of filaments on solid agar 
. Furthermore, strains lacking the function of the early meiotic gene IME4
display both meiotic defects and an increased ability to adhere to agar, a phenotype associated with PH development 
In yeast, IME4
encodes the sole functional member of a class of RNA-modifying enzymes conserved throughout eukaryotes 
. These enzymes, identified by homology to the N6
-adenosyl methyltransferase in humans, MT-A70, catalyze the post-transcriptional methylation of adenosine (to form N6
A) in RNA. The function of this modification on mRNA is as yet unclear. In vitro
work suggests that m6
A enhances the translational activity of modified messages 
, whereas in vivo
experiments suggest that this modification may play an additional role in message stability and processing 
. Although this form of RNA methylation is barely detectable in yeast undergoing mitotic growth, m6
A accumulates on mRNA molecules during meiosis 
. Strains encoding catalytically inactive alleles of IME4
do not accumulate m6
A and display defects in meiotic entry 
. Ime4 modifies the transcripts of IME1
under these conditions, which may explain these defects upon nutrient starvation 
Here, we investigated the role of mRNA methylation in the programmed response to nutrient starvation. Because earlier work had shown that cells remain capable of resuming mitotic growth until the exit from meiotic G2 (reviewed in 
), we examined the early starvation response in temporal detail. We found that cells were already committed to a starvation response after meiotic cell cycle entry, because they formed PH buds when returned to nutrient-rich conditions. Lineage restriction during this period was partially dependent on the RNA methylation activity of Ime4, which had separable roles in promoting meiosis and inhibiting PH growth. Both functions also required Mum2 and Slz1, two poorly understood meiotic proteins that interacted with Ime4 and, like Ime4, were necessary for maintaining normal levels of meiotic mRNA methylation. These results point to a central role of mRNA methylation in coordinating starvation-induced developmental decisions in yeast.