Volatile compounds produced by maize silks in response to Fusarium verticillioides infection and its association with the lipoxygenase pathway

CAMPOS BERMUDEZ VA; FAUGUEL CM; FERNANDEZ M; IGLESIAS J; PRESELLO DA; ANDREO CS

Simposio; 32nd New Phytologist Symposium; 2013

Fusarium verticillioides is one of the most common fungal pathogens in maize and the principal agent causing ear rot in Argentina. Plant oxylipins are largely recognized as agents involved in defense response to pathogenic attack. The majority of oxylipins are produced through the lipoxygenase (LOX) pathway, including C6 and C9 volatiles compounds. Since maize silks are considered to be the principal route of entry for F. verticillioides, we evaluate the in vitro effect of silks volatiles production on pathogen growth in two maize genotypes with contrasting F. verticillioides resistance. We found that while the resistant line inhibited pathogen development, the susceptible line seems to favors its growth. With the aim to identify the volatile compound produced in each genotype we analyzed both samples by SPME and GC-MS. We found that the resistant line exhibited different and higher relative concentration of 13-LOX branch-derived volatiles compared to the susceptible line. Real time PCR of several transcripts of the LOX genes showed that inoculation increased the expression of almost all transcripts analyzed. In addition, higher basal expression of two genes belonging to 13-LOX branch was observed in the resistant genotype. These results indicate that volatiles produced by 13-LOX branch could be associated with resistance against F. verticillioides.