Sensitivity to p H and ability to modify ambient p H of the take‐all fungus G aeumannomyces graminis var. tritici

• Published in: Plant pathology Vol. 63; no. 1; pp. 117 - 128
• Main Authors: Lebreton, L., Daval, S., Guillerm‐Erckelboudt, A.‐Y., Gracianne, C., Gazengel, K., Sarniguet, A.
• Format: Journal Article
• Language: English
• Published: 01.02.2014
• ISSN: 0032-0862; 1365-3059
• DOI: 10.1111/ppa.12062

p H is one of the major ambient factors affecting life history traits of soilborne phytopathogenic fungi. The diversity of phenotypic responses to p H changes has not been extensively explored within fungal populations. To investigate this question, the ability of 82 strains of a worldwide collection of the take‐all agent G aeumannomyces graminis var. tritici ( G gt) to grow in controlled p H conditions, reflecting their p H sensitivity, was measured. Of these 82 strains, 37 belonged to the G 1 type and 45 to the G 2 type, the two main genetic groups identified in G gt populations. The experiments were conducted in P etri dishes on F ahraeus solid media buffered at p H 4·6, 6·0 or 7·0 with citrate–disodium phosphate solutions. The 82 strains exhibited a wide range of hyphal growth rates at the three p H levels. Ten statistically different p H profiles were described. The G 2 strains grew significantly better than the G 1 on the slightly acidic (p H 6·0) and the neutral (p H 7·0) buffered media. The ability of three strains to change ambient p H was also measured on unbuffered F ahraeus solid media initially adjusted to p H 5·6 or 8·0. All three strains were able to alkalinize the acidic medium. However, important variations between strains in the intensity, range and persistence of this alkalinization were measured. These results provide the first evidence of intraspecific variability in p H sensitivity within soilborne fungal species.