Abstract
Background: Rice (Oryza
sativa L.), which is a staple food for more than half of the world’s population,
is frequently attacked by herbivorous insects, including the rice stem borer,
Chilo suppressalis. C. suppressalis substantially reduces rice yields in
temperate regions of Asia, but little is known about how rice plants defend
themselves against this herbivore at molecular and biochemical level. Results:
In the current study, we combined next-generation RNA sequencing and
metabolomics techniques to investigate the changes in gene expression and in
metabolic processes in rice plants that had been continuously fed by C.
suppressalis larvae for different durations (0, 24, 48, 72, and 96 h).
Furthermore, the data were validated using quantitative real-time PCR. There
were 4,729 genes and 151 metabolites differently regulated when rice plants were
damaged by C. suppressalis larvae. Further analyses showed that defense-related
phytohormones, transcript factors, shikimate-mediated and terpenoid-related
secondary metabolism were activated, whereas the growth-related counterparts
were suppressed by C. suppressalis feeding. The activated defense was fueled by
catabolism of energy storage compounds such as monosaccharides, which meanwhile
resulted in the increased levels of metabolites that were involved in rice plant
defense response. Comparable analyses showed a correspondence between transcript
patterns and metabolite profiles. Conclusion: The current findings greatly
enhance our understanding of the mechanisms of induced defense response in rice
plants against C. suppressalis infestation at molecular and biochemical levels,
and will provide clues for development of insect-resistant rice
varieties.