Pochonia chlamydosporia Induces Plant-Dependent Systemic Resistance to Meloidogyne incognita

Abstract

Meloidogyne spp. are the most damaging plant parasitic nematodes for horticultural crops worldwide. Pochonia chlamydosporia is a fungal egg parasite of root-knot and cyst nematodes able to colonize the roots of several plant species and shown to induce plant defense mechanisms in fungal-plant interaction studies, and local resistance in fungal-nematode-plant interactions. This work demonstrates the differential ability of two out of five P. chlamydosporia isolates, M10.43.21 and M10.55.6, to induce systemic resistance against M. incognita in tomato but not in cucumber in split-root experiments. The M10.43.21 isolate reduced infection (32–43%), reproduction (44–59%), and female fecundity (14.7–27.6%), while the isolate M10.55.6 only reduced consistently nematode reproduction (35–47.5%) in the two experiments carried out. The isolate M10.43.21 induced the expression of the salicylic acid pathway ( PR-1 gene) in tomato roots 7 days after being inoculated with the fungal isolate and just after nematode inoculation, and at 7 and 42 days after nematode inoculation too. The jasmonate signaling pathway ( Lox D gene) was also upregulated at 7 days after nematode inoculation. Thus, some isolates of P. chlamydosporia can induce systemic resistance against root-knot nematodes but this is plant species dependent.

Commercial Formulates of Trichoderma Induce Systemic Plant Resistance to Meloidogyne incognita in Tomato and the Effect Is Additive to That of the Mi-1.2 Resistance Gene

“…Dasher II were used for this study. For the split-root and the combination of plant resistance with T34 to an avirulent M. incognita population experiments, seeds were surface sterilized following the procedure described in Ghahremani et al (2019).…”

“…Resistance to an Avirulent M. incognita Population by T. asperellum T34 and T. harzianum T22 Tomato and cucumber were grown in a split-root system, following the procedure described in Ghahremani et al (2019), in which the plant root is divided into two halves transplanted in two adjacent pots: the inducer, inoculated with the antagonist, and the responder, inoculated with the nematode. The main root of 5-day-old seedlings was excised, and plantlets were individually transplanted into seedling trays containing sterile vermiculite and maintained in a growth chamber at 25 ± 2 • C with a 16/8 h (light/dark) photoperiod for 2 weeks for cucumber and 3 weeks for tomato plants.…”

“…The inducer part of the root was inoculated with a suspension of 10 5 cfu of T. harzianum T22 (T22) or T. asperellum T34 (T34) just before transplanting. This fungal dosage was selected because it was the same at which P. chlamydosporia induced resistance in tomato (Ghahremani et al, 2019). One week later, the responder part of the root was inoculated with the avirulent M. incognita population Agròpolis at a rate of 1 J2 cm −3 of soil (RKN).…”

“…This fungal species is frequently isolated from RKN eggs produced in vegetable crop roots cultivated in northeastern Spain (Giné et al, 2012) and has been reported as the main biotic factor responsible for soil suppressiveness to RKN in this area (Giné et al, 2016). In addition, it has been reported that some P. chlamydosporia strains can induce systemic resistance in tomato plants (Ghahremani et al, 2019). Consequently, the proper use of Trichoderma must consider the possible side effect on fungal nematode antagonists present in soils.…”

The bacterial community structure dynamics inMeloidogyne incognitainfected roots and its role in worm-microbiome interactions

“…The interaction of M. incognita virulence and microbial taxa in the various niches they occupy, have been studied in the context of biological control, revealing complex relationships, which efficacy diminishes with the transfer from lab to field [20] . Common themes in this line of research include the isolation of Meloidogyne pathogens from the cuticle of second stage juveniles (J2) [21][22][23] , or the identification of soil microbes and bacterial volatile compounds with antagonistic effects [24,25] , key taxa including Rhizobia [26] , Trichoderma and Pseudomonas [27,28] , Pasteuria [29] , Pochonia [30,31] and some mycorrhiza [31][32][33] .…”