The Transcription Factor OsWRKY45 Negatively Modulates the Resistance of Rice to the Brown Planthopper Nilaparvata lugens

Abstract

WRKY transcription factors play a central role not only in plant growth and development but also in plant stress responses. However, the role of WRKY transcription factors in herbivore-induced plant defenses and their underlying mechanisms, especially in rice, remains largely unclear. Here, we cloned a rice WRKY gene OsWRKY45, whose expression was induced by mechanical wounding, by infestation of the brown planthopper (BPH, Nilaparvata lugens) and by treatment with jasmonic acid (JA) or salicylic acid (SA). The antisense expression of OsWRKY45 (as-wrky) enhanced BPH-induced levels of H2O2 and ethylene, reduced feeding and oviposition preference as well as the survival rate of BPH, and delayed the development of BPH nymphs. Consistently, lower population densities of BPH on as-wrky lines, compared to those on wild-type (WT) plants, were observed in field experiments. On the other hand, as-wrky lines in the field had lower susceptibility to sheath blight (caused by Rhizoctonia solani) but higher susceptibility to rice blast (caused by Magnaporthe oryzae) than did WT plants. These findings suggest that OsWRKY45 plays important but contrasting roles in regulating the resistance of rice to pathogens and herbivores, and attention should be paid if OsWRKY45 is used to develop disease or herbivore-resistant rice.

Silencing OsSLR1 enhances the resistance of rice to the brown planthopper Nilaparvata lugens

“…The number of nymphs, eggs and female and male adults of BPH and the white‐backed planthopper (WBPH) Sogatella furcifera and the number of predatory spiders in each block were recorded once a week from 9 August to 12 October in 2014 and from 30 July to 11 October in 2015 following the method described in Huangfu et al . (). As the population density of SSB was very low, we did not investigate this pest.…”

“…In the plot, five lines (the two irSLR1 lines, the two oeSLR1 lines and their corresponding WT line) in 2014 and six lines (the two irSLR1 lines, the three oeSLR1 lines and their corresponding WT line) in 2015 were randomly assigned to 15 or 18 blocks, each line with three independent replicate blocks. The number of nymphs, eggs and female and male adults of BPH and the white-backed planthopper (WBPH) Sogatella furcifera and the number of predatory spiders in each block were recorded once a week from 9 August to 12 October in 2014 and from 30 July to 11 October in 2015 following the method described in Huangfu et al (2016). As the population density of SSB was very low, we did not investigate this pest.…”

Current understanding of the molecular players involved in resistance to rice planthoppers

“…During the activation of signaling networks and expression of defense‐related genes, transcription factors play an important role, for example the transcription factors WRKY46 and WRKY72 potentiate defense gene expressions and rice immune responses . At least six transcription factors have been identified as conferring rice resistance to planthoppers, including OsWRKY45 , OsWRKY53 , OsWRKY70 , OsWRKY89 , OsHLH61 and OsHLH96 . Antisense expression of OsWRKY45 ( as‐wrky45 ) enhances rice resistance to BPH .…”

“…At least six transcription factors have been identified as conferring rice resistance to planthoppers, including OsWRKY45 , OsWRKY53 , OsWRKY70 , OsWRKY89 , OsHLH61 and OsHLH96 . Antisense expression of OsWRKY45 ( as‐wrky45 ) enhances rice resistance to BPH . BPH‐induced H 2 O 2 and ethylene levels were enhanced in as‐wrky45 lines, and the preference for feeding and oviposition and the survival rate of BPH were reduced by 17% and 10%, respectively in the laboratory; the number of BPH nymphs feeding on as‐wrky45 lines was markedly lower than that on wild‐type in the field .…”

“…Antisense expression of OsWRKY45 ( as‐wrky45 ) enhances rice resistance to BPH . BPH‐induced H 2 O 2 and ethylene levels were enhanced in as‐wrky45 lines, and the preference for feeding and oviposition and the survival rate of BPH were reduced by 17% and 10%, respectively in the laboratory; the number of BPH nymphs feeding on as‐wrky45 lines was markedly lower than that on wild‐type in the field . The resistance of rice to BPH decreased when OsWRKY53 was silenced and it improved when OsWRKY53 was over‐expressed .…”