Race profiling and phylogenetic analysis of the root knot nematode Meloidogyne incognita presages the possible emergence of virulence towards cotton in Central India

Abstract With a host range spanning vegetables, pulses, grains, fruits, and cash crops such as cotton, the polyphagous root knot nematode (RKN) Meloidogyne incognita is known globally as the most economically destructive genus of plant parasitic nematodes. During sampling efforts, severe root galling from RKN infestation was observed on cotton as well as several other vegetable crops in Nagpur, Wardha, Chandrapur, Jalgaon, Aurangabad and Yavatmal districts of the Vidarbha region of Maharashtra in Central India. M. incognita has been reported as the predominant nematode species in irrigated cotton growing regions of Northwestern India, but in the surveyed regions, the reniform nematode Rotylenchulus reniformis has been reported instead on cotton as the predominant species. As well, the sampled RKN populations were found in areas with soil characteristics not matching previously reported habitat conditions, pointing to the ability of RKN populations to tolerate and adapt to a wider variety of soil conditions than expected. Race profiling from differential host studies indicated all six populations to belong to race 3. Maximum likelihood analysis between the sampled populations and catalogued populations of M. incognita from other Indian states, based on the rDNA Internal Transcribed Spacer (ITS) region showed the populations to form a phylogenetic grouping, thus indicating the potential of Indian populations to exhibit increased pathogenicity towards cotton. As it stands, with cotton as the dominant crop of the region alongside other vegetable crops, the found results underscore the need for proactive surveillance of nematode infestations of cotton.