Mexican Journal
of Phytopathology

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• Phytopathological note
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In vitro evaluation mycoparasitic capacity of Irpex lacteus P7B against fungi and oomycetes associated with plant diseases

By Francisco Palemón Alberto, Santo Ángel Ortega Acosta*, Erubiel Toledo Hernández, Cesár Sotelo Leyva, Guadalupe Reyes García, Elizabeth Tecomulapa Acatitlán

* Corresponding Author. Email: / Institution: Universidad Autónoma de Guerrero

Accepted: 15/November/2024 – Published: 04/December/2024 – DOI: https://doi.org/10.18781/R.MEX.FIT.2024-21

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Abstract Background/Objective. Diseases of agricultural crops affect the yields and quality of products. Synthetic chemical compounds are generally used to control them; these cause harmful impacts to the environment, as well as to human health. In this sense, beneficial microorganisms can be used in agriculture as biocontrol agents, and contribute to obtaining food in sufficient and safe quantities. The fungus Irpex lacteus has been reported as a potential biocontrol agent. The objective of this research work was to evaluate the in vitro mycoparasitic capacity of the endophytic fungus I. lacteus P7B against 22 fungi and one oomycete associated with plant diseases.

Materials and Methods. The P7B isolate, previously detected as a mycoparasite, was used and molecularly identified by amplification and sequencing of the internal transcribed spacer (ITS) region of ribosomal DNA, using primers ITS1/ ITS4.The confrontations of the mycoparasite (P7B) against the phytopathogenic microorganisms were carried out in PDA culture medium. Three replicates were used for each microorganism, in addition to the controls, which consisted of placing the microorganisms individually.

Results. Molecular analyses determined that isolate P7B corresponded to Irpex lacteus (GenBank: PP922180). The results of the in vitro assays indicated that I. lacteus P7B inhibited all the phytopathogenic agents with which it was confronted, 100% inhibition by I. lacteus occurred approximately in 14 days, except for Rhizopus spp., this was at 23 days after the confrontations.

Conclusion. The present study demonstrates that the fungus I. lacteus presented 100% in vitro mycoparasitic capacity against the various fungi and an oomycete evaluated, so future work could focus on evaluating its mycoparasitic activity under field conditions.

Keywords: biocontrol agent, phytopathogens, mycoparasite.

Figure 1. Effect of the confrontation in dual culture in PDA under in vitro conditions between I. lacteus P7B against fungi and an oomycete associated to plant diseases.

Figure 3. Effect of the confrontation in dual culture in PDA under in vitro conditions between I. lacteus P7B against fungi and an oomycete associated to plant diseases. P7B = Irpex lacteus. CC47GRO = Corynespora cassiicola. COLTOR1 = Colletotrichum gloeosporioides. PAP-4= Phytophthora sp. C4 = Macrophomina sp. RIZOPAP = Rhizopus sp. Dac = Days after confrontation.

Figure 3. Effect of the confrontation in vitro of I. lacteus P7B against fungi and an oomycete. A= Macrophomina sp. (isolate C4) control; B= Macrophomina sp. (isolate C4) confronted with I. lacteus P7B, a degradation of sclerotia and hyphae can be observed. C = Alternaria sp. (isolate AL1) control; D = Alternaria sp. (isolate AL1) confronted with I. lacteus P7B, in which a degradation of conidia and hyphae can be observed. E = Rhizopus sp. (isolate RIZOPAP) control; F = Rhizopus sp. (isolate RIZOPAP) confronted with I. lacteus P7B, shows degraded sporangia. Images captured with anoptic microscope with 10X (A, B, E and F), and 40X objective lens (C and D).

Table 1. Microorganisms used in the evaluation for the confrontation with Irpex lacteus P7B from the collection of pyhtopathogenic fungi of the Plant Physiology and Biotechnology Laboratory, FCAA-UAGro.