Background: Isothiocyanates (ITCs) are natural products obtained from plants of the Brassicas family. They
represent an environmentally friendly alternative for the control of phytopathogenic fungi. However, as it has
been observed with synthetic fungicides, the possibility of inducing ITC-resistant strains is a major concern.
It is, therefore, essential to understanding the molecular mechanisms of fungal resistance to ITCs. We analyzed
a subtractive library containing 180 clones of an
Alternaria alternata
strain resistant to 2-propenyl ITC (2-pITC).
After their sequencing, 141 expressed sequence tags (ESTs) were identified using the BlastX algorithm. The
sequence assembly was carried out using CAP3 software; the functional annotation and metabolic pathways
identification were performed using the Blast2GO program.
Results: The bioinformatics analysis revealed 124 reads with similarities to proteins involved in transcriptional
control, defense and stress pathways, cell wall integrity maintenance, detoxification, organization and
cytoskeleton destabilization; exocytosis, transport, DNA damage control, ribosome maintenance, and RNA
processing. In addition, transcripts corresponding to enzymes as oxidoreductases, transferases, hydrolases,
lyases, and ligases, were detected. Degradation pathways for styrene, aminobenzoate, and toluene were
induced, as well as the biosynthesis of phenylpropanoid and several types of N-glycan.
Conclusions: The fungal response showed that natural compounds could induce tolerance/resistancemechanisms
in organisms in the same manner as synthetic chemical products. The response of
A. alternata to the toxicity
of 2-pITC is a sophisticated phenomenon including the induction of signaling cascades targeting a broad set
of cellular processes. Whole-transcriptome approaches are needed to elucidate completely the fungal response
to 2-pITC.
