Transcriptome analysis of roots from resistant and susceptible rice varieties infected with Hirschmanniella mucronata.

Hirschmanniella mucronata is a plant-parasitic nematode that is widespread in rice production areas and causes 10-25% yield losses a year on average. Here, we investigated the mechanism of resistance to this nematode by comparing the transcriptomes of roots from resistant (Jiabali) and susceptible (Bawangbian) varieties of rice. Of 39 233 unigenes, 2243. exhibited altered total expression levels between control and infected resistant and susceptible varieties. Significant differences were observed in the expression levels of genes related to stress, peptidase regulation or inhibition, oxidoreductase activity, peroxidase activity and antioxidant activity. The up-regulated genes related to plant secondary metabolites, such as phenylpropanoid, lignin, cellulose or hemicellulose, may result in an increase in the degree of resistance of Jiabali to the H. mucronata infection compared with that of Bawangbian by affecting cell wall organization or biogenesis. Of the genes that responded similarly to H. mucronata infection, ~252 (~76.59%) showed greater changes (whether induced or suppressed) in RN155 (susceptible varieties infected by rice root nematode) than in RN51 (resistance varieties infected by rice root nematode). Nineteen pathogenesis-related genes belonging to nine pathogenesis-related gene families were significantly induced by H. mucronata in the infected roots of Jiabali and Bawangbian, and 13 differentially expressed genes showed changes in their abundance only in the susceptible Bawangbian variety. This study may help enhance our understanding of the mechanisms underlying plant resistance to nematodes.