Physiological Response Of Rice To Brown Planthopper And The Study Of Small Brown Planthopper MicroRNA

The rice planthopper which mainly includes brown planthopper (SBPH, Niaparvata lugens Stal,) small brown planthopper (SBPH, Laodephax striatellus Fallen), and white-backed planthopper (WBPH, Sogatella furcifera Horvath), is considered as one of the most destructive pests of rice(Oryza sativa L.) and it caused serious harm for the yield of rice in a long time. BPH and WBPH cause loss of rice yield mainly by directly sucking the phloem sap of the rice leaf sheath, as well as transmitting some viruses, while SBPH can cause damage to rice mainly by transmitting various plant viruses. Humanity has been looking for the most economical, efficient and environment-friendly strategy to control the damage caused by this insect in a long time. In this research, two methods were used to evaluate the BPH resistance of several rice varieties and two wild rice varieties with Bph12and Bph14were identified. Furthermore, the relationship between rice and rice planthopper were studies through the changes of free amino acids and proteins in different rice leaf sheath which were infested different times by BPH and the miRNA of SBPH. The purpose of this study is to lay the foundation for exploring the intrinsic molecular mechanism of the different rice varieties can cause different resistance after being infested by rice planthopper. The main contents and results of this study are listed as below:1. The free amino acid (FAA) of directly and indirectly part of leaf sheath in TN1, IRRI-IRGC-10173and W1181after BPH infested Oh,12h,24h,48h, and96h were measured through the physiological fluid system of automatic amino acid analyzer. The results showed that the total FAA in IRRI-IRGC-10173was more than that in TN1not only at the different parts but also at the different times after BPH infested. Compared with TN1, the difference of total FAA between directly and indirectly infested parts in IRRI-IRGC-10173was on the uptrend with the reaction time. The change of all the FAA in IRRI-IRGC-10173was stronger than that of TN1. This showed that the metabolism and transport capacity of the IRRI-IRGC-10173was stronger than that of TN1after BPH infested different times. The conversion relationship between Asparagine (Asn) and aspartate (Asp) and glutamine (Gln) and glutamate (Glu) may associate with the resistance of rice for BPH.2. The proteins of leaf sheath among susceptible rice TN1, resistance rice (IRRI-IRGC-10173and W1181) were separated and studied by two dimensional gel electrophoresis (2-DE). Mass spectrum (MS) identification results showed that stress responsive protein, peroxidase, glycosyl hydrolase, amino acid metabolism enzymes, organic acid metabolism enzymes, photosynthesis related enzymes, protein modification enzymes, and RNA binding protein were significant changes in expression in response to BPH infested. GO analysis showed that these differential proteins mainly associated with metabolic process, combination and catalytic functions. The proteins in IRRI-IRGC-10173and W1811showed strongly involved in the dicarboxylic acid metabolic pathways (osa00630). Three proteins A02(LOC_Os08g01930)、A25(LOC_Os11g06720), and X1(LOC_Os11g13890) in IRRI-IRGC-10173very likely was regulated by rice miRNA. EF hand family protein only appeared in W1181after BPH infested96h. IRRI-IRGC-10173showed stronger response ability in many aspects in response to BPH infested, and the Glycine cleavage system H protein was appeared in it, but vanished in TN1after BPH infested96h. In conclusion, the above results indicated that W1181and IRRI-IRGC-10173have an efficient and specific defense mechanism to resist BPH infested which maybe comes from the resistant gene.3. In this study, we provided the first miRNA identification in small brown planthopper by NGS. Totally501mature miRNAs, which include227conserved and274novel miRNAs were identified. Stem-loop RT-PCR was applied to confirm the validation of miRNA. The conservative analysis of the38miRNA families which include69conserved miRNA showed that their highly conserved in the Arthropoda phylum. MiRanda predicted2701unique target genes for378miRNAs, and52function terms were predicted by GO annotation. The function of miRNA target genes was found to be very similar between conserved miRNA and novel miRNAs. In this study, the resistance rice varieties with different resistance genes were identified which were used as material for next step research. The measure and analysis for the free amino acid and proteins showed that there are different response of different resistance rice against the infested by BPH in the level of free amino acid and proteins. This result provided certain reference to explore the internal mechanism between rice and rice planthopper. On the other hand, the sequencing of miRNA in SBPH greatly enriched the miRNA database of insects, and it’s laid a solid foundation for the study of the growth and development of SBPH.