Functional Analysis Of XprG Proteins In Magnaporthe Grisea

Ndt80/PhoG like DNA-binding family include the DNA-binding region of Ndt80as well as PhoG and its homologues. In Saccharomyces cerevisiae, it is named Ndt-80binding protein, which could be a component of the machinery in regulating the transition into nuclear division. In Aspergillus nidulans, its homologue was determined in charge of extracellular proteases from responding to nutrient starvation. In Neurospora crassa, the Ndt-80domain containing VIB-1was implicated as a regulator of vegetative incompatibility.It is shown that there are three homologues, MGG₀0622.6, MGG₀0729.6, MGG₀1475.6, containing Ndt-80domain in Magnaporthe grisea genome database. The alignment of these putative amino acid sequences and analysis on their phylogenetic relationship among MGG₀0622.6, MGG₀0729.6, MGG₀1475.6indicate that they share low identities, by contrast three homologues share comparable identities with the Ndt-80containing proteins among A. nidulans, N.crassa and S. cerevisiae respectively, which may suggest that three homologues function specifically under evolutionary force.The phenotypic analysis on the three single gene deletion mutants and one double deletion mutant between MGG00622.6and MGG00729.6demonstrate the reduction on condiation with different levels, especially for△Mgg00729and△Mgg00622-00729which both show50%of decline. Meanwhile, the appresorium formation in each mutant is postponed slightly, as well as the mating capacity is compromised. Therefore, it’s possible that the loss of function for XprG in M.grisea leads to the dysfunction of mechanism, which could work upstream of sporulation process, in responding to the environmental cues.In comparison with the wide type strain, the△Mgg00622,△Mgg00079and their double deletion mutants experience faster growth in minimal medium with BSA as the sole nitrogen source, moreover the colony morphology of double deletion mutant shows expansive trend indicating more suitable growth.△Mgg00622,△Mgg00729,△Mgg01475as well as the double deletion mutant outgrow the wide type strain slightly in minimal medium with glucose as the sole carbon source, which might suggest XprG’s role in general response to nutrient limitation. In S. cerevisiae, the initiation and progression for meiosis require nutrient deprivation, specifically induced by limitation of nitrogen, carbon, sulfur or phosphate. The identity between XprG and Ndt80indicate their general responsibility for detecting nutritional status and controlling the progression through meiosis.