Occurrence,Identification And Molecular Detection Of Meloidogyne Enterolobii On Vegetable In Fujian Province

Meloidogyne enterolobii is considered as one of the most damaging root-knot nematode species in tropical and subtropical areas.Little research on vegetable diseases caused by M.enterolobii has been done in Fujian Province.The systematic suvey and identification of M.enterolobii on vegetable has been conducted.The research result has provided fundamental theory for mamagement of vegetable disease caused by M.enterolobiiin Fujian Province.During 2014 to 2016,the major vegetable bases in 9 regions in Fujian Province has been survey by taking sample of root-knot nematodes.Four species of root-knot nematode were identified based on morphological and molecular characteristics and molecular detection.The nematodes were as followed:M.incognita,M.arenaria,M.javanica and M.enterolobii.M.incognita were dominant species on vegetable bases in Fujian Province.M.enterlobii as been identified from the root of Daucus carota,Capsicum annuum,and Ipomoea aquatica in the southern Fujian region and caused severe economic losses.This is the first report of M.enterolobii on Capsicum annuum or Ipomoea aquatic,and Ipomoea aquatic is new host of M.enterolobii.M.enterolobii may existed in vegetabe bases by single species population or mixed populations with M.incognita.The results have been showed that pathogen dentification of root-knot nematode disease of guava on 14 orchards on southern areas and central areas of Fujian Province were M.enterolobii.The results based on field investigation and inoculation tests have been showed that the Psidium guajava or seedlings parasitizing by M.enterolobii may be the important primary source of infection of vegetable disease caused by M.enterolobii in some vegetable bases in southern areas of Fujian Province.The mtDNA CO ?-lrRNA region sequences of 12 populations of M.enterolobii parasitizing on Daucus carota,Capsicum annuum,Ipomoea aquatic and Psidium guajava were amplified and sequenced.Phylogenetic trees derived from Bayesian analysis based on the regions of mtDNA CO ?-lrRNA showed that 12 populations of M.enterolobii were are robustly positioned at a monophyletic group harboring only all sequences of M.enterolobii available from the GenBank database and can be differentiated from other root knot nematode species.The results of inoculum tests showed that M.enterolobii,M.incognita and M.javanica could cause serious infection on Daucus carota.Severely infected carrots are stubby,galled and forked and therefore unmarketable.The symptoms caused by M.enterolobii were different from those of the other two root-knot nematodes.The typical symptoms on roots caused by M.enterolobii were many rounded to irregular shaped lumps and swellings on the surface of tap and fibrous roots,often with a marked proliferation of small roots with nodules at the site of the gall.The symptoms on root caused by the other two root-knot nematodes were little lumps on the surface of roots,small galls to develop on secondary roots.Irregular shaped lumps and swellings on the surface of tap and fibrous roots,often with secondary roots emerging from the galls on taproots.Based on the results and previous survey data,M.enterolobii has been introduced into in southern Fujian regionand showing a rapidly spread in vegetable base.M.enterolobii is becoming one of the most important pathogen nematode.