Molecular and morphological characterisation of Meloidogyne hapla populations from Ethiopia

摘要

Meloidogyne hapla, considered mainly a temperate species, was recently detected parasitising rose plants in glasshouses in Ethiopia. Roses are grown in more than 80% of the existing cut-flower producing farms in Ethiopia. Nevertheless, its production is increasingly facing serious nematode problems. Consequently, soil samples were collected from 12 randomly selected farms distributed in six districts around Addis Ababa. Nine of these farms were positive for Meloidogyne spp. and six were positive for M. hapla. Pure isolates of 125 Meloidogyne spp. from the latter six farms were established from single egg masses on tomato cv. Moneymaker. Based on molecular and morphological data, eightytwo of the isolates were identified as M. hapla. Morphological characters based on light and scanning electron microscope images together with morphometric measurements of females, males and second-stage juveniles (J2) were compared with populations of M. hapla from different countries. In addition, molecular characterisation was performed based on the 28S D2-D3 expansion segments within the ribosomal DNA and the region located between cytochrome oxidase unit II and the 16S rRNA gene of the mitochondria (mtDNA). Morphological characters of females, males and J2 were in line with descriptions of other M. hapla populations but there were a few exceptions in morphometric measurements. The female perennial pattern of the Ethiopian populations fitted the original description but was smaller than that of the population described by Jepson. The J2 body size was larger compared to previous descriptions from Hawaii and East Africa and the a ratio value was much greater than for the East African population but similar to the Hawaiian population. Phylogenetic relationships of the Ethiopian M. hapla population with other related Meloidogyne species on the bases of both mtDNA and D2-D3 expansion segment sequence analysis revealed highly supported clades containing the Ethiopian isolates as well as other published isolates from different countries.