Abstract
Abstract
In this study, we induced mutations in the genome of
Trichoderma harzianum
(NAS-T101) via gamma irradiation to enhance its antagonistic potential against
Pythium ultimum.
Efficacy testing of mutants and the wild type was conducted in a completely randomised design (CRD) with four replications in the greenhouse on lettuce (Grand Rapid cultivar) at the Nuclear Agriculture Research Institute collection (NSTRI, AEOI) in spring 2018. The experiments included plants treated with
T. harzianum
NAS-T101 (non-irradiated) and its selected mutant TM4 against the
P. ultimum
pathogen, and the control plant. Disease incidence (DI), morphological traits (length and dry weight of shoots and roots), and physiological traits (total protein, peroxidase, polyphenol oxidase, chlorophyll
a
and
b,
and malondialdehyde activity) were measured. The results showed that
T. harzianum
(NAS-T101 and TM4) significantly reduced DI and developed the plant root system.
T. harzianum
(NAS-T101 and TM4) treatments increased the accumulation of proteins of molecular weight associated with peroxidase and polyphenol oxidase enzymes, enhanced their activity, and led to a significant increase in chlorophyll
a
and
b
. The TM4 treatment showed a significant increase in antioxidant enzyme activities and protein accumulation compared to the control. This study showed that the mutant (TM4) was significantly more efficient at biocontrol of
P. ultimum
than its parental, un-irradiated isolate, and that lettuce plants treated with TM4 maintained morphological and physiological processes under disease conditions.