Transcriptome analysis of biotic and abiotic stress mediated by the suction of brown planthopper in two rice cultivars

RH (Rathu Heenati), an indica rice cultivar from Sri Lanka, is highly resistant to several different biotypes of brown planthopper (Nilaparvata lugens Stal, BPH). In contrast, another indica rice cultivar, TN1 (Taichung Native 1), is highly susceptible to all biotypes of BPH. To reveal the molecular biological mechanism of biotic and abiotic stress mediated by BPH suction in two rice cultivars, RH and TN1, the genome-wide gene expressional profiling of these two rice varieties at 6 h after BPH infestation and needle puncturing was conducted by performing transcriptome analysis. In total, six samples (T6C, T6N, T6B, R6C, R6N, and R6B) were collected after performing different treatments for this expressional analysis. The results provide important information for the further isolation of BPH-resistance genes from RH as well as research on the mechanism of BPH resistance in RH. The transcriptome results revealed that TN1 (a BPH-susceptible rice variety) and RH (a BPH-resistant rice variety) harbor different pathways that respond to the physical injury of acupuncture and BPH infestation. The susceptible variety TN1 is more sensitive to the physical damage caused by acupuncture, whereas in the resistant variety RH, the response to insect damage is more rapid and direct. By comparing the gene changes of various plant hormones between the two varieties under different stresses, it was found that, in addition to the traditional SA and ET pathways related to the feeding induction of piercing-sucking pests, the expression patterns of JAZrelated genes in the JA signaling pathway also changed under two stresses (acupuncture induction and brown planthopper feeding induction), while the IAA hormone pathway-related genes in the susceptible variety TN1 also changed significantly after brown planthopper feeding. Furthermore, the results of this study help us to understand the biological process of rice responses to BPH and provide a promising direction to identify BPHresistance-related genes in RH.