Transcriptome analysis reveals key genes associated with root-lesion nematode Pratylenchus thornei resistance in chickpea

The root-lesion nematode, Pratylenchus thornei, is one of the major plant-parasitic nematode species causing significant yield losses in chickpea (Cicer arietinum). In order to identify the underlying mechanisms of resistance to P. thornei, the transcriptomes of control and inoculated roots of three chickpea genotypes viz. D05253 > F3TMWR2AB001 (resistant advanced breeding line), PBA HatTrick (moderately resistant cultivar), and Kyabra (susceptible cultivar) were studied at 20 and 50 days post inoculation using the RNA-seq approach. On analyzing the 633.3 million reads generated, 962 differentially expressed genes (DEGs) were identified. Comparative analysis revealed that the majority of DEGs upregulated in the resistant genotype were downregulated in the moderately resistant and susceptible genotypes. Transcription factor families WRKY and bZIP were uniquely expressed in the resistant genotype. The genes Cysteine-rich receptor-like protein kinase 10, Protein lifeguard-like, Protein detoxification, Bidirectional sugar transporter Sugars Will Eventually be Exported Transporters1 (SWEET1), and Subtilisin-like protease were found to play cross-functional roles in the resistant chickpea genotype against P. thornei. The identified candidate genes for resistance to P. thornei in chickpea can be explored further to develop markers and accelerate the introgression of P. thornei resistance into elite chickpea cultivars.

Host suitability of different common bean varieties in a growth room to the plant-parasitic nematodes Pratylenchus thornei and P. neglectus

Summary Pratylenchus thornei and P. neglectus attack common bean and cause economic yield losses throughout cultivated areas in Turkey. The most effective management strategy for the P. thornei and P. neglectus infections is crop rotation with non-host crops and breeding resistant/tolerant varieties. However, parent bean genotypes immune to P. thornei and P. neglectus are not available for breeding programmes; thus, resistant varieties are commonly incorporated as parents. In the present research, a total of 36 common bean varieties were tested in a growth room for their host response to these two nematode pests. The reproduction factor and the population density of both nematode species were calculated. All tested bean varieties showed varying levels of resistance and susceptibility to P. thornei and P. neglectus. Among the dry bean varieties, nine were found to be resistant to P. thornei and three to P. neglectus, with three varieties (‘Kantar-05’, ‘Önceler-98’ and ‘Karacasehir-90’) resistant to both species. Among fresh bean varieties, ten were found to be resistant to P. thornei and four to P. neglectus, with four varieties (‘Helda’, ‘Gina’, ‘Gelincik’ and ‘Bourgondia’) resistant to both species. The resistant common bean varieties identified in this study are a valuable untapped genetic pool that will offer improved resistance levels to P. thornei and P. neglectus, especially ‘Gina’ and ‘Önceler-98’, which seem to possess a great source of resistance to P. thornei and P. neglectus, respectively, and can be used in breeding programmes in the near future.

Investigating the Impact of Root-Lesion Nematodes (Pratylenchus thornei) and Crown Rot (Fusarium pseudograminearum) on Diverse Cereal Cultivars in a Conservation Farming System

In two experiments on a farm practicing conservation agriculture, the grain yield of a range of wheat cultivars was significantly (p < 0.001) negatively related to the post-harvest population densities of Pratylenchus thornei in the soil profile to 45 cm depth. In a third and fourth experiment with different rotations, methyl bromide fumigation significantly (p < 0.05) decreased (a) a low initial population density of P. thornei in the soil profile to 90 cm depth and (b) a high initial population of P. thornei to 45 cm depth, and a medium level of the crown rot fungus, Fusarium pseudograminearum, at 0–15 cm depth to a low level. For a range of wheat and durum cultivars, grain yield and response to fumigation were highly significantly (p < 0.001) related to (a) the P. thornei tolerance index of the cultivars in the third experiment, and (b) to both the P. thornei tolerance index and the crown rot resistance index in the fourth experiment. In the latter, grain yield was significantly (p < 0.001) positively related to biomass at anthesis and negatively related to percentage whiteheads at grain fill growth stage. One barley cultivar was more tolerant to both diseases than the wheat and durum cultivars. Crop rotation, utilizing crop cultivars resistant and tolerant to both P. thornei and F. pseudograminearum, is key to success for conservation farming in this region.