Plant-parasitic nematode associated with wheat in central, eastern, and south-eastern Kazakhstan

Kazakhstan is one of the biggest wheat producers, however, its wheat production is far below the average international wheat production standard due to biotic and abiotic stressors. Plant-parasitic nematodes are devastating for cereal production systems worldwide. A comprehensive survey was conducted in 2019 to identify plant-parasitic nematodes associated with wheat in different locations of central, eastern, and south-eastern Kazakhstan. The results revealed 33 root-lesion and 27 cyst nematode populations from the 77 localities sampled. These two genera occurred in separate or in mixed populations. The root-lesion populations were identified as Pratylenchus neglectus and P. thornei while all cyst nematodes were identified as Heterodera filipjevi. The identification of nematodes was firstly performed based on morphological and morphometric features and confirmed by BLAST and phylogenetic analyses based on the internal transcribed spacer and the D2-D3 expansion located in the 28S gene of ribosomal DNA for CCN and RLN populations, respectively. Pratylenchus neglectus and P. thornei populations from Kazakhstan showed a high similarity with the American, European, and Asian populations. Heterodera filipjevi populations formed a well-supported cluster with the corresponding populations from different countries and showed a slightly intraspecific polymorphism. Kazakhstan populations of H. filipjevi may have multiple introductions in Kazakhstan due to the divergence among them. The results of this study are of great importance for breeding programs and will enable awareness to extension advisors to develop measures to control these nematodes in cereal cropping areas in Kazakhstan.

Pathotypes Detected Among Populations of Pratylenchus neglectus Collected From Montana

The root lesion nematode, Pratylenchus neglectus, is one of the most damaging nematodes to affect wheat worldwide. The nematode is widely distributed in Montana, primarily affecting winter wheat within the state. Managing the nematode primarily involves rotation to resistant and moderately resistant crops (peas, lentils, and barley). A nematode survey was conducted across the state nearly 10 years after an initial survey, to reassess the nematode threat and assess the impact of changing trends in crop rotations. To assess the broad applicability of rotation crops to control P. neglectus across Montana, greenhouse trials were conducted to challenge rotational crops using eight populations of P. neglectus collected from geographically diverse locations across the state. In the trials, conducted with four Montana crops, a significant interaction was detected between crop and nematode population (analysis of variance P < 0.001). Populations from Hill, Dawson, and Chouteau counties were found to be pathogenic on barley. Male nematodes were detected in seven of the eight pot culture populations, and these were confirmed to be P. neglectus by morphological and molecular methods. These results suggest a re-evaluation of barley and lentils as a management option for P. neglectus in Montana, as pathotypes for each exist within the state.