Interactions between nitrogen and silicon in rice and their effects on resistance towards the brown planthopper Nilaparvata lugens

Authors: WU, XIAOYING - South China Agricultural University; YU, YAOGUANG - South China Agricultural University; LIANG, GUOHUA - South China Agricultural University; Baerson, Scott; Pan, Zhiqiang - Peter; SONG, YUANYUAN - South China Agricultural University; DING, CHAOHUI - South China Agricultural University; WU, WANGHUI - South China Agricultural University; NIU, JUNBO - South China Agricultural University; ZENG, RENSEN - South China Agricultural University

Submitted to: Frontiers in Plant Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/5/2017
Publication Date: 1/23/2017
Publication URL: https://handle.nal.usda.gov/10113/5801788
Citation: Wu, X., Yu, Y., Liang, G., Baerson, S.R., Pan, Z., Song, Y., Ding, C., Wu, W., Niu, J., Zeng, R. 2017. Interactions between nitrogen and silicon in rice and their effects on resistance towards the brown planthopper Nilaparvata lugens. Frontiers in Plant Science. doi:10.3389/fpls.2017.00028.

Interpretive Summary: For many years, treatment of plants with the mineral silicon has been known to improve their ability to withstand the effects of a wide variety of stresses, including so-called biotic stresses such as insect attack and infection by pathogenic microorganisms. The production and release of defensive compounds such as allelochemicals has also been shown to increase in response to silicon amendment to soils. Nitrogen is one of the most critical nutritional elements required by plants, and emerging evidence suggests that a mutually antagonistic relationship exists between nitrogen and silicon accumulation in certain plant species such as rice. High nitrogen fertilization levels tend to inhibit silicon uptake, and conversely, silicon amendment may lead to reduced plant nitrogen uptake in rice. In this report we examine the roles played by genes associated with silicon uptake, nitrogen uptake, as well asregulatory pathways associated with the production of allelochemicals and other defense compounds under various nitrogen and silicon fertilization schemes. We also show that interactions between nitrogen and silicon can adversely impact resistance levels towards herbivorous insect pests, using the brown planthopper (Nilaparvata lugens) as a test case.

Technical Abstract: Nitrogen (N) and silicon (Si) are two important nutritional elements required for plant growth, and both impact host plant resistance toward insect herbivores. The interaction between the two elements may therefore play a significant role in determining host plant resistance. We have investigated this interaction in rice (Oryza sativa L.) and its effect on resistance to the herbivore brown planthopper Nilaparvata lugens, (BPH). Our results indicate that high-level (5.76 mM) N fertilization reduced Si accumulation in rice leaves, and furthermore, this decrease was likely due to decreased expression of Si transporters OsLsi1 and OsLsi2. Conversely, reduced N accumulation was observed at high N fertilization levels when Si was exogenously provided, and this was associated with down-regulation of OsAMT1;1 and OsGS1;1, which are involved in ammonium uptake and assimilation, respectively. Under lower N fertilization levels (0.72 and/or 1.44 mM), Si amendment resulted in increased OsNRT1:1, OsGS2, OsFd-GOGAT, OsNADH-GOGAT2 and OsGDH2 expression.Additionally, bioassays revealed that high N fertilization level significantly decreased rice resistance to BPH, and the opposite effect was observed when Si was provided. These results provide additional insight into the antagonistic interaction between Si and N accumulation in rice, and the effects on plant growth and susceptibility to herbivores.