Reproductive, pathogenic and genotypic characterisation of five Meloidogyne graminicola populations from the Philippines on susceptible and resistant rice varieties

Abstract

Five populations of Meloidogyne graminicola isolated from different rice-growing areas in the Philippines were characterised. The populations showed little phenotypic variability of second-stage juveniles and female perineal pattern. Differences in reproduction among M. graminicola populations were not observed on mature resistant Oryza glaberrima varieties ‘TOG5674’, ‘TOG5675’, ‘RAM131’ and ‘CG14’, or on susceptible O. sativa varieties ‘IR64’ and ‘UPLRi-5’. In all infected rice varieties, plant growth and yield-contributing traits showed no differences among the populations. A search on M. graminicola populations from the Philippines for single-nucleotide polymorphism on the sequences of Internal Transcribed Spacer (ITS) of rDNA genes and mtDNA indicated only few points of heteroplasmy. Nematode reproduction and disease induction of the five M. graminicola populations in the Philippines exerted the same level of aggressiveness and virulence. The absence of resistance-breaking populations of M. graminicola is important for the maintenance of durability of resistance to this important rice pathogen