Submitted to: Plant Pathology
Publication Type: Peer reviewed journal
Publication Acceptance Date: 11/21/2003
Publication Date: 12/31/2003
Citation: Ueng, P.P., Reszka, E., Chung, K.R., Arseniuk, E., Krupinsky, J.M. 2003. Comparison of glyceraldehyde-3-phosphate dehydrogenase genes in phaeosphaeria nodorum and p. avenaria species. Plant Pathology. 12:255-268. Interpretive Summary: Stagonospora leaf blotch diseases in cereals are caused by two important Phaeosphaeria pathogens, P. nodorum and P. avenaria. Their identification is mainly based on asexual spore morphology. We found that sequence diversity in glyceraldehyde-3-phosphate dehydrogenase gene, coding an important enzyme for sugar consumption, can distinguish and identify these two species. Also, synthesis of identical proteins in these two Phasosphaeria species indicates that they are closely related in their evolution. This information will serve as a valuable reference for scientists and others who are interested in pathogen identification, fungal evolution and plant disease control.
Technical Abstract: Stagonospora leaf blotch of cereals is a complex disease caused by several Phaeosphaeria fungal species. Genetic diversity of glyceraldehyde-3-phosphate dehydrogenase (GPD) genes in Phaeosphaeria nodorum, P. avenaria f. sp. triticea (P.a.t.) and P. avenaria f. sp. avenaria (P.a.a.), three causal agents of stagonospora leaf blotch diseases in cereals, was investigated. The PCR-amplified GPD gene coding sequences in these cereal Phaeosphaeria species had 4 introns. The sizes of GPD genes in wheat-biotype P. nodorum isolates were variable, from 1,253-1,255bp. Sequence variations in intron 4 was used to divide the wheat-biotype P. nodorum isolates into two subgroups. These two subgroups were equally present in a survey of field wheat-biotype P. nodorum isolates. Except Pat2, the GPD genes in Pat1 and Pat2 of the P.a.t. group, the P. a.a. group and the barley-biotype P. nodorum were 1,251bp in length and phylogenetically closely related. Since the nucleotide changes in GPD genes occurred mostly in intron regions and the third codons of amino acid coding triplets, the deduced peptide sequences in cereal Phaeosphaeria species were identical, except for Pat2. The GPD peptide in Pat2 isolates had two amino acid substitutions. The deduced GPD proteins of these Phaeosphaeria species are closely related to that in a maize pathogen, Cochliobolus heterostrophus. Based on phylogenetic analysis, the possible evolution of these Phaeosphaeria species with other ascomycetes is discussed.