All strains reached a height of 75 mm, although ISPaVe1018 did so with the greatest frequency. By 18 and 21 dpi, when symptoms of the virulent strains were obvious on all plants, both race 1,2 strains could be reisolated all along the stems, although ISPaVe1018 was faster and more continuous SKLB1002? than ISPaVe1083. Conversely, the avirulent strain was never recovered from the highest section of the stems from 18 dpi and onwards. A con tinuity index was established for each plant by consider ing the presence or absence of the fungus in adjacent pairs of stem sections. Generally, the distribu tion of fungus along the stem was discontinuous at the early time Inhibitors,Modulators,Libraries points, although more continuity was shown by race 1.
A peculiar pattern was shown at 8 dpi because the highest section allowing successful rei solation was lower than at 1 4 dpi, and the pathogen distribution was still discontinuous for all races. From 14 dpi onwards, colonization along the stem differed significantly between the virulent and avirulent strains, and the more extensive coloniza tion shown by the race 1,2 strains Inhibitors,Modulators,Libraries was Inhibitors,Modulators,Libraries coupled with the appearance of obvious symptoms. In the late phase, continuous distribution was observed for all three strains, but for race specific reasons. Both virulent strains were continuously distributed along the entire stem length, whereas the avirulent strain was continuously absent from the highest section of the stem, and continuously present in the lower sections. Plants inoculated with race 1 remained symptomless until the end of the experiment, although the pathogen could still be reisolated.
The fun gus was never reisolated Inhibitors,Modulators,Libraries from uninoculated plants. All three strains could be reisolated from the stem base regardless of the time point. cDNA AFLP analysis We carried out a cDNA AFLP analysis on RNA samples from both healthy and infected melon plants to identify differentially expressed transcripts putatively associated with the infection process and resistance response. RNA samples from the three fungal strains grown in vitro were also included in the analysis, first to help identify fungal transcripts expressed specifically Inhibitors,Modulators,Libraries in planta and second to identify fungal genes differentially expressed in vitro among the three strains. Because the fungus could be reisolated from infected stems starting from 1 dpi in all interactions, samples of infected plants were collected for cDNA AFLP analysis at 2, 4, 8 and 21 dpi.
These time points were selleck catalog intended to take into account the early stages of infection, but also to allow the detection of pathogen transcripts when infec tion was well established and the mycelia produced at the late stage were abundant. RNA was also collected from uninfected plants as a control. The expression pat terns of approximately 7000 transcripts were monitored with 128 different BstYI 1 MseI 2 primer combina tions for selective amplification.