ts provided an overview of the transcriptional changes occurring

ts provided an overview of the transcriptional changes occurring in infected melon plants, the limited availability of sequence data made it difficult to draw firm conclusions about the molecular events occurring in infected plants. Of the 115 TDFs identified in Cluster C, 41 did not match any database sequences or matched sequences most that have yet to be annotated. The remaining 74 TDFs encode well known components of disease resistance responses and related signal transduction cascades, such as calmodulin and calmodulin binding proteins, transcription factors, a 12 oxophytodienoate reductase, and a 13S lipoxygenase involved in jasmonic acid biosynthesis, and enzymes involved in the biosynthesis of secondary metabolites acting as antimicrobial compounds, or in a general stress responses, such as xanthine dehydrogenase and betaine aldehyde dehydrogenase.

Genes encoding pathogenesis related proteins such as endochitinase, beta 1,3 glucanase and a type I proteinase inhibitor like protein were also specifically modulated in the compati ble interaction. Altogether, transcripts related to the defense, response to stimulus and secondary metabolism categories accounted for 25% of modulated TDFs in Cluster C. These findings further support the hypothesis that a delayed defense response might indeed be respon sible for symptom development. Cluster C also contained genes potentially involved in the establishment of susceptibility, such as those related to auxin accumulation. Several reports indicate that an increase in auxin levels in the cell can contribute to dis ease susceptibility and that a similar increase can be induced by pathogens in order to facilitate coloniza tion.

TDFs with homology to an indole 3 acetic acid amino synthetase and to an IAA type protein Q75GK0 are specifically induced in the compatible interac tion. However, other genes in Cluster D that induce auxin signaling are repressed by both viru lent strains, but induced by the avirulent strain at 21 dpi. The overall picture is therefore complex and Anacetrapib sug gests that the compatible interaction mainly involves transcriptional changes that are otherwise typical of effective resistance responses. It is tempting to speculate that the recessive resistance identified in Asian acces sions might be related to the lack of a plant reaction and thus to better tolerance of the infection process.

Transcriptional changes in the incompatible interaction Resistance responses are generally characterized by rapid and extensive reprogramming of transcriptional activity, especially in race specific interactions. However, that resistance of Charentais Fom 2 to FOM race 1, although mediated by a single R type resistance gene, is not com plete, since fairly the fungus can always be reisolated from the stem of Charentais Fom 2 plants. In our model system we noted surprisingly few transcriptional changes speci fically associated with the incompatible interaction. These included a calmodulin related protein, stably upregulat

Leave a Reply

Your email address will not be published. Required fields are marked *

*

You may use these HTML tags and attributes: <a href="" title=""> <abbr title=""> <acronym title=""> <b> <blockquote cite=""> <cite> <code> <del datetime=""> <em> <i> <q cite=""> <strike> <strong>