Abstract:

Cucumis metuliferus is an important breeding resource for resistance to root-knot nematodes in Cucurbitaceae family. Peroxidase gene（CMPOD）was cloned from the CM3 line using primers of homologous sequences. There was 97% nucleotide sequence similarity in POD gene between CM3 and C. sativus‘9930’. POD gene mainly expressed in root of CM3 infected by Meloidogyne incognita，and the expression increased at the early stage of nematodes inoculation. POD gene expression reached the highest point at 3 d post inoculation. Moreover，temperature affected the POD gene expression which peaked at 20 ℃. When the temperature was above 20 ℃，POD gene expression reduced but the number of egg masses and galls increased with the rise of temperature. The trend showed a negative correlation between POD gene expression and the number of egg masses and galls. However，the nematode-resistance of CM3 was not compromised with increasing temperature and CM3 still showed resistance at 35 ℃. These results revealed that the root-knot nematodes resistance of CM3 was  heat-stable，which could be utilized for crop breeding. Together，our studies provided an important basis to demonstrate the molecular mechanism of nematode-resistance of CM3.

Key words: Cucumis metuliferus, peroxidase gene, Meloidogyne incognita, resistance, heat stability