Biochemical and Genetic Responses of Fungi to the Toxic Effect of Synthetic and Natural Fungicides

María-Elena Báez-Flores ,Rosalba Troncoso‐Rojas ,Martín-Ernesto Tiznado-Hernández

doi:10.3844/ajabssp.2008.348.357

María-Elena Báez-Flores , Rosalba Troncoso‐Rojas + Show 1 more

Open Access

https://doi.org/10.3844/ajabssp.2008.348.357

Copy DOI

Abstract

The objective of the present review is to analyze the molecular basis of fungicide resistance mechanism to both synthetic fungicides and the natural fungicides isothiocyanates. The review is focused mainly on Alternaria sp., but whenever available, similar studies in other fungi have been included. Fungal resistant strains to dicarboximide and phenylpyrrole fungicides have been found to contain mutations in one of the proteins involved in the signal transduction pathway that regulates the fungal response to osmotic stress. By the other hand, it was found that isothiocyanates induce enzymes like glutathione S-transferase, cyanide hydratase, heat shock proteins, membrane transporters and proteins associated with the oxidative stress response. Also, inter simple sequence repeats polymorphism was recorded as a response to the isothiocyanates treatment. The knowledge about the genetic basis of the response mechanism of Alternaria sp. to the isothiocyanates is scarce. Therefore, studies by DNA recombinant technology to analyze the fungi responses to fungicides, will allow knowing the metabolic pathways involved in the phenomena to permit the design of strategies to inhibit key reactions involved in the fungal resistance, reaching a better and sustainable fungal infections control.

Highlights

Produce postharvest losses are due to pre-harvest factors[1], poor harvesting techniques[2], bad practices of handling[3] as well as bacterial[4] and fungal infections[5]
In the dic1 mutant strain E4504, introduction of the wild type Bmhk1 reversed the osmosensitivity and fungicide resistant phenotypes, while the phenotypes of Dic2 and Dic3 mutants were not affected. These results suggested that phenotypic alterations observed in dic1 mutant strains are due to mutations in the Bmhk1 gene
In the test for sensitivity to osmotic stress the mycelial growth behavior of all A. alternata isolates was significantly reduced at 4% sodium chloride, while the fungicide resistant isolates were only slightly more sensitive to osmotic stress than the sensitive isolates[18]

Summary

INTRODUCTION

Produce postharvest losses are due to pre-harvest factors[1], poor harvesting techniques[2], bad practices of handling[3] as well as bacterial[4] and fungal infections[5]. It is important to elucidate the genetic changes due to the fungicides use in fungal strains that became resistant, in order to develop effective and environmentally friendly strategies to control fungi infections[12]. The authors proposed that A. alternata resistance to iprodione was mediated by a mutation in a twocomponent histidine kinase (HK) gene They amplified a genomic fragment encoding a two component HK protein from an iprodione sensitive field isolates of A. alternata showing high homology to previously identified genes from other fungal species, like N. crassa[42] and Botrytis cinerea[43]. The AbNIK1 gene, encoding a two component histidine kinase protein, was isolated from a wild type dicarboximide and phenylpyrrole sensitive Alternaria brassicicola strain and compared with the corresponding histidine kinase genes from fungicide resistant strains (field and laboratory mutant strains)[19].

CONCLUSION

Findings

Relationships between Genetic Polymorphisms and