Study On Resistance Mechanism Of NR Pumpkin To Meloidogyne Incognita

Root knot nematode is a kind of plant parasitic nematode,host plants more than 5500 species,containing the food crops,vegetables and fruit crops and other economic crops.Greenhouse cucumber is the main cucumber production mode in China,which is seriously harmed by root-knot nematodes.They suppresess crop growth and developments,production,even cause huge economic losses more than 100 billion dollars in world agricultural productivity a year.At present,the control of root-knot nematodes mainly depends on chemical nematicide.However,the side effect of chemical nematicide,such as environmental pollution,soil ecological destruction,nematodes resistance and pesticide residue,lead us to find a green and safe control measure.The use of resistant crop varieties to effectively control root knot nematode is green,safe and pollution-free.To screen for novel resistant resource,the control effect of NR pumpkin strain on Meloidogyne incognita was evaluated.The main contents are as follows:After inoculation 35 d,the average number of root knots on Zhongnong 6 cucumber was 255.5,and the average number of egg mass per plant was 6.6,while the average number of root knots on NR pumpkin was only 41.4 and no egg mass,which was significantly less than that of cucumber.The control effect of root knots of NR pumpkin was 83.8%,which showed that NR pumpkin can effectively control M.incognita.The development of M.incognita at different time points in NR pumpkin and Zhongnong 6 cucumber was observed.The growth and development of M.incognita in NR pumpkin root was slower than that in cucumber.During the early stage in nematode infection,NR pumpkin root produce more ROS than cucumbe.The phobotaxis test showed that the phobotaxis rate of NR pumpkin root tip against M.incognita was 38.0 % and higher than that of cucumber with 69.4% after 12 h treatment.To reveal the expression of genes involved int defense responses,the fluorescence quantitative PCR was conducted.The results demonstrated that the expression trend of PR1 and LOX1 in NR pumpkin and cucumber exhibit the same treand after inoculation with M.incognita,as well as PR1 expression was up-regulated,while LOX1 gene was down-regulated.The CTR1 gene was significantly up-regulated in NR pumpkin,but no changes in cucumber,indicating that the susceptible ET signaling pathway related to giant cell formation was inhibited in NR pumpkin.The results showed that NR pumpkin regulated the expression of genes involved in defense responses defend against M.incognita.In the field experiment,the disease index of NR pumpkin grafted seedlings against M.incognita was reduced by 38.7,the control effect was 56.9%,and and the cucumber yield increased 31.8%.The results showed that NR pumpkin grafted seedlings could not only effectively control M.incognita,but also increase the yield of cucumber.In conclusion,the NR pumpkin had good control effect on M.incognita,which provided a new way for cucumber against root-knot nematode.