Abstract
The technique of Differential Display RT-PCR has been optimized and used to compare expression of gene transcripts between control root tissue and giant cell enriched tissues of tomato plants infected with Meloidogyne javanica. A total of 25 up- or down- differentially expressed bands were identified in 33P labelled autoradiograms using DD-RT PCR. Of these, 12 bands were cloned and sequenced. The expression of 6 was studied in more detail. Using semi-quantitative real time fluorescence RT-PCR, normalized against expression of actin, the expression of five of these genes was studied at four times after infection (5, 15, 25 and 30 days). The results showed that one was highly up-regulated (IC9, 69-fold up-regulated at 15 days), one was strongly down-regulated (HA/HT1, 28-fold down-regulation at 15 days), two showed about 10-fold changes in expression, and one was similar in expression to the control. Significantly, the sixth transcript (IC1) was of nematode origin, although it was routinely isolated from giant cell enriched tissue. If this is not a contaminant it may be the first evidence for a nematode transcript in giant cells.