Antioxidant system is involved in arbuscular mycorrhizal symbiosis, but its role during the colonization process is
still poorly understood. To gain new insights into the role of antioxidant system during root colonization by arbuscular
mycorrhizal fungi, the activities of key antioxidant enzymes were evaluated in tomato (
Solanum lycopersicum
L.) roots
inoculated with six strains of different genera and species: two
Glomus mosseae
,
Glomus cubense
,
Glomus intraradices
,
Glomus
sp. and
Acaulospora scrobiculata
.
Glomus cubense
and
A. scrobiculata strains reached the highest infectivity
levels with maximum values of colonization frequency and intensity of 29-10.88% and 18-9.20%, respectively;
G. mosseae
strains showed an intermediate infectivity, both with 15% of colonization frequency and maximum intensities of 7.64-
7.06%, respectively; while the infectivity levels of
Glomus sp. and
G. intraradices strains were the lowest with colonization
frequency- 13% and intensities- 5.07 and 5.41, respectively. Some activity patterns of peroxidase, superoxide dismutase,
and polyphenol oxidase enzymes were not specific for early or late colonization stages neither for the colonization level and
type of strain. However, a unique superoxide dismutase-band presents at early colonization and the low level of guaiacolperoxidase
activity at later stages presents in all inoculated roots indicate that these antioxidant responses are independent
of colonization degree and strain. Taking together, our data suggest that alterations of the antioxidant enzyme activities are
not general characteristics of the colonization process by arbuscular mycorrhizal fungi, probably having the key role on
those responses the specific feature of each strain rather than colonization
per se.
