The influence of the fungal pathogen Mycocentrospora acerina on the proteome and polyacetylenes and 6- methoxymellein in organic and conventionally cultivated carrots (Daucus carota) during post harvest storage

Summary

Carrots may have to be discarded during post harvest cold storage due to development of fungal infections, caused by, e.g., liquorice rot caused by Mycocentrospora acerina. Control of this disease is mainly based on cultural practice. We compared the susceptibility of carrots grown under conventional and organic agricultural practices. We
have developed a bioassay for infection studies of M. acerina on carrots and observed that organic roots were more susceptible after one month storage than conventional ones but no differences were apparent after four or six months storage. Levels of three polyacetylenes (falcarinol, falcarindiol and falcarindiol-3-acetate) and the isocoumarin
phytoalexin (6-methoxymellein) were analysed. No changes in individual and total polyacetylene content were observed; however, 6-methoxymellein accumulated in infected tissue as well as in healthy tissue opposite the infection. The proteomes of carrot and M. acerina were characterized by 2-DE and MALDI TOF-TOF. The intensity of 33 plant protein spots was significantly changed in infected roots including up regulation of defence and stress response proteins but also a decrease of proteins involved in energy metabolism. This combined metabolic and proteomic study indicates, that roots respond to fungal infection by altering its metabolism which includes simultaneous induction of 6-methoxymellein and synthesis of defence related proteins.