Overexpression of a Xylanase Inhibitor Gene, OsHI-XIP, Enhances Resistance in Rice to Herbivores

Xylanase inhibitors have been reported to play an important role in plant defense against fungal pathogens. However, little to nothing is known about their role in defense against herbivores. Here, we cloned a rice xylanase-inhibiting protein (XIP)-type gene OsHI-XIP whose encoding protein is located in the endoplasmic reticulum (ER). Transcriptional analysis revealed a low constitutive mRNA level of OsHI-XIP, while herbivore infestation, mechanical wounding, and treatment with jasmonic acid (JA), a signal that can be induced after infestation by the rice striped stem borer (SSB) Chilo suppressalis, result in an obvious increase in transcript levels. Overexpression of OsHI-XIP, which increased mRNA levels of the gene by 14.7- to 17.7-fold and 7.5- to 9.6-fold at 0 and 12 h, respectively, after SSB infestation, enhanced constitutive and SSB-induced xylanase inhibitor activity and reduced the larval performance of SSB. Moreover, overexpression of OsHI-XIP decreased the feeding and oviposion preferences of the rice brown planthopper (BPH) Nilaparvata lugens, but did not influence the growth and development of rice plants. The results suggest that the rice XIP-type xylanase inhibitor OsHI-XIP is involved in the resistance in rice to herbivores.