Ionomics against Orseolia oryzae（rice gall midge）in rice

【Objective】 To explore changes of different nutrients in rice gall midge（RGM）-infested rice plants，and to provide new ideas for RGM prevention and control and resistance mechanism elucidation.【Method】 RGM-resistant nearisogenic line 43W-NIL and susceptible line 9311 were taken as materials，and inductively coupled plasma mass spectrometry（ICP-MS）technique was used to determine nutrient element content in RGM-resistant and-susceptible rice materials at 0，5，7 and 9 d of inoculation；changes of key elements induced by insect infestation were verified by hydroponic method；and expression of genes related to nutrient element metabolism was determined in susceptible material by qRT-PCR. 【Result】 A total of 25 nutrient elements were identified by ionome analysis，and most of them differed greatly in resistant and susceptible materials or before and after RGM infestation. After RGM inoculation，compared with 9311 at 0 d，in 43W-NIL， contents of Ti， K， P and S elements were higher， while contents of Pb， Sr and Ca elements were lower. Principal component analysis of the ionome revealed that the PC1 and PC2 components explained 40.0% and 24.7% of the variance，respectively. Principal component loading analysis showed that according to variation of Ca，Sr，Co，Pb，Be， Sb，Fe，Ti，P，S，and K content，resistant and susceptible materials could be distinguished，and in order of importance， elements affecting RGM resistance were Ca，Sr，P，K，and Co. The inoculation experiment of hydroponic plants revealed that high concentrations of exogenous Ca treatment promoted RGM larvae growth in resistant rice，while low P and K concentration treatments inhibited RGM larvae growth in susceptible materials. According to qRT-PCR results， calcium-regulated protein gene（OsCML20）expression showed the same changing trend as Ca²⁺ ion content，while potassium transporter protein gene（OsHAK12）expression showed a decrease and then an increase in both resistant and susceptible materials.【Conclusion】 Three elements，Ca，P and K may play a key role in the response of rice to RGM infestation. OsHAK12 and OsCML20 genes may be the important genes in RGM resistance expression mechanism. Ionomics could help explore difference of rice during RGM infestation，so as to provide new ideas for studies on plant insect resistance mechanism.