Molecular biology of root lesion nematodes (Pratylenchusspp.) and their interaction with host plants

Abstract

Plant-parasitic nematodes of the genus Pratylenchus are among the top three most significant nematode pests of crop and horticultural plants worldwide. There are more than 70 described species, most are polyphagous with a wide range of host plants. Because they do not form obvious feeding patterns characteristic of sedentary endoparasites (e.g. galls or cysts), and all worm-like stages are mobile and can enter and leave host roots, it is more difficult to recognise their presence and the damage they cause. As a result their study has been relatively neglected, despite being the major nematode pests of staple crops such as wheat in dryland agriculture in Australia and the Pacific Northwest of the USA. The current status of molecular research on Pratylenchus spp. is described, including molecular diagnostics for their detection in soil samples, the status of breeding for resistance or tolerance, transcriptome data from deep sequencing, and their amenability to powerful new transgenic strategies for control using gene silencing (RNAi) technology. A comparison of the repertoire of enzymes and putative effectors used by Pratylenchus species to enter roots, migrate from cell-to-cell, suppress host defence responses and feed successfully with those present in sedentary endoparasites provides new insights into which effectors are required for migratory phases versus feeding site induction for sedentary endoparasites. The genomics era has finally arrived for Pratylenchus species, and it can be predicted that new genomic information will lead to new strategies to control this neglected but economically important group of plant pests.