Dear Faryal. Concerning your issue about the low pH (acidic) pH regulation genes in fungi. Fungi respond to their environments by tailoring their output of activities destined for the cell surface or beyond to the ambient pH. We are beginning to glimpse how they sense ambient pH and transmit this information to the transcription factor, whose roles ensure that a suitable collection of gene products will be made. Although relatively little is known about pH signal transduction itself, its consequences for the cognate transcription factor are much clearer. Intriguingly, homologues of components of this system mediating the regulation of fungal gene expression by ambient pH are to be found in the animal kingdom. The potential applied importance of this regulatory system lies in its key role in fungal pathogenicity of animals and plants and in its control of fungal production of toxins, antibiotics, and secreted enzymes. I think the following below links may help you in your analysis:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC120796/pdf/0019.pdf

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4855365/pdf/12864_2016_Article_2665.pdf

http://onlinelibrary.wiley.com/doi/10.1002/j.1460-2075.1993.tb06072.x/pdf

Thanks