ارزیابی واکنش بیوشیمیایی مقاومت ارقام تجاری انار به نماتد ریشه گرهی Meloidogyne incognita

Pomegranate is one of the most popular fruits and one of the most important export products in Iran. Root-knot nematodes (Meloidogyne spp.) are one of the most destructive plant parasites in pomegranates, which primarily cause galls in the root system, disrupting the function of absorbing, transferring water and nutrients, and eventually lead to reduced growth and production of pomegranate fruit. Using resistant cultivars is the best way to control of root-knot nematodes. To find resistant cultivars in plants, changes in the activity of oxidative enzymes can be used as a biochemical marker. In this research, the biochemical reaction of cuttings of 25 commercial cultivars and a native genotype of Qaemshahr forest of pomegranate was investigated by measuring the amount of peroxidase (POX), polyphenol oxidase (PPO), phenylalanine ammonialyase (PAL) enzymes at different time intervals after infection by Meloidogyne incognita. The activity of all enzymes was similar and in none of them, on the first day after infection, no significant difference was observed between the infected treatments with nematodes and the control. The amount of peroxidase enzyme showed a significant difference between infected and non-infected cultivars after the third day. The highest activity of peroxidase enzyme was observed in all infected cultivars by nematode five days after inoculation. Enzyme activity increased until the fifth day and then decreased. The highest amount of enzyme was observed in the native genotype, followed by Shirine Shahvar, Rababe Ney Riz, Ardestani Khorasan, Shirineh Shehvare Yazdi, Dokhtar Hamoumi and the lowest in Farugh. The changes in polyphenol oxidase enzyme in all cultivars except the native genotype was very low. Enzyme level gradually increased in infected cultivars three days after nematode inoculation. This increased level continued until the seventh day of infection and then decreased. The highest level of polyphenol oxidase enzyme activity was observed in the native genotype, which was significantly different from other cultivars. After that, Dokhtare Hamomi, Rababe Ney Riz, Ardestani Khorasani, Shirine Shahvare Yazdi and Ameneh Khatouni cultivars showed the highest level of polyphenol oxidase enzyme on the seventh day. The highest level of phenylalanine ammonialyase enzyme activity was observed seven days after nematode inoculation in infected cultivars. The highest level of the enzyme was in the native genotype, followed by Gol Tafti, Ardestanie Khorasani and Shisheh Kap Ferdous, the lowest level of enzyme was in Farugh and Shirine Shahvar cultivars. Enzyme activity in nematode-infected cultivars gradually decreases after the seventh day. The results of the investigation showed that the native genotype has the highest level of enzyme activity in all three enzymes, and Farugh and Shirine Shahvar cultivars have the lowest enzyme levels.