초록

Ⅳ. 연구개발결과
벼-RSV-애멸구간 interactomes연구, 식물 환경스트레스 저항성 및 노화 지연 연구, 스트레스대응 벼 MAP Kinase 기능 연구 및 산소결핍 환경스트레스 하에서의 벼세포 에너지 항상성 관리에 관한 연구들을 통해 다양한 유전자들을 동정하였고, 스트레스 저항성 관련 기능 연구를 수행하였다.

Abstract ▼

Rice (Oryza sativa L.) is an important cereal crop worldwide. Rice stripe virus (RSV) has become a major pathogen in rice causing serious damage on the yield of rice and transmitted by the small brown planthopper (SBPH). To reveal the molecular interactions of the rice-RSV-SBPH, we used diverse geno

Rice (Oryza sativa L.) is an important cereal crop worldwide. Rice stripe virus (RSV) has become a major pathogen in rice causing serious damage on the yield of rice and transmitted by the small brown planthopper (SBPH). To reveal the molecular interactions of the rice-RSV-SBPH, we used diverse genomic approaches. Firstly, we used yeast-two hybrid system to identify potential rice genes resistant to RSV and to reveal interactions of RSV proteins. Several rice proteins involved in RSV resistance were identified and self-interaction of RSV-CP and RSV-NS3 proteins were revealed. RNA-Seq was conducted to establish expression profiles upon RSV infection. We found that down-regulation of genes related to photosynthesis and flowering was strongly associated with disease symptoms caused by RSV and up-regulation of genes involved in metabolic pathways,stress responses, and transcription was related with the host defense mechanism. To find SBPH genes associated with RSV infection, a transcriptomic approach was performed identifying various SBPH genes involved in RSV infection. Taken together, our study was the first comprehensive study of interactomes for rice-RSV-SBPH by various genomic methods.
To characterize functions of abiotic stress- and senescence-related genes and to elucidate signaling and regulation mechanisms on these, we studied several genes that have been partially studied in our previous researches, and in addition we selected many other useful genes through screening of their interactors and by web-based high throughput screening. We found that SAF1, which is a F-box protein, represses the endothecium secondary cell wall thickening in anther and that AtMYB20 negatively regulates PP2Cs in ABA signaling to enhance salt tolerance. Moreover, we identified that CaM regulates DNA binding activity of bZIP4 to response many stresses and that nuclear-localized AIF1 binds to TFs and modulates their DNA binding ability, thus regulates expression of PP2C genes, leading to stress tolerance. By web-based screening, we isolated 37 genes whose expressions are increased by ABA, and 11 and 10 genes respectively showing increased and decreased expression in the progress of senescence, and we analyzed their promoters in detail. In this study, we were able to publish eight articles in SCI journals and one in non-SCI international journal, and registered four patents and applied eight patents, and registered 14 bioinformatic data in RDA.
Abiotic stresses such as drought, high salinity and extreme temperatures are major factors that cause losses in crop productivity. In plants, MAP (mitogen-activated protein) kinases play important roles in adaptive responses to these stresses. Genome-wide analyses of MAP kinases revealed that there are approximately 75 putative MAP kinases in the rice genome. However, little is known about their functions in stress response. In this study, we attempted to identify MAP kinases that regulate stress response. Toward the end, we carried out expression analyses of all rice MAPKs and MAPKKs and several MAPKKKs. Based on their expression patterns, we chose stress-regulated MAP kinases and investigated their in vivo and in vitro functions. Our results indicate that OsMAPKK6 and OsMAPKKK63 are involved in drought and salt responses. Furthermore, our interaction studies suggest that they may function in the same pathways regulating high salt and drought responses.
Rice seeds can anaerobically germinate and grow due to their high resistance to O2-deficient conditions. Also, the germinating seeds behave very sensitive to the change in sugar environment as a complete hetrotrophic system, which totally depend their growth on endospermic reserves. Diverse mechanisms contributing to the maintenance of the cellular energy status was investigated in various ways to understand the way to establish and maintain the cellular energy homeostasis. First, the study of calcineurin B-like (CBL) interacting protein kinase 15 (CIPK15), a positive regulator to direct the O2 deficiency signal to the sugar signaling cascade revealed how the CIPK15 transcripts are temporally accumulated in response to sugar starvation and that hexokinase mediates the sugar regulation of this gene. Also, sugar regulation of CIPK15 could be interfered by O2 deprivation and inhibition of oxidative phosphorylation, indicating that hexokinase-mediated sugar signaling may be coordinated with the cellular energy status.Analysis of a transgenic rice cell line harboring the GUS reporter gene under the control of the CIPK15 promoter demonstrated that the crosstalk between sugar regulation and metabolic status occurs at the CIPK15 promoter. In our examination, expression of many of anaerobically induced genes were commonly responsive to sugar, either under the control of hexokinase or non-hexokinase mediated signaling cascades.Only sugar regulation via the hexokinase pathway was susceptible for O2 deficiency or energy deficit conditions evoked by uncoupler. Examination of sugar regulation of those genes under anaerobic conditions revealed the presence of multiple paths underlying anaerobic induction of gene expression in rice, subgrouped into three distinct types.
Our study of interaction between sugar signaling and anaerobic conditions has suggested that sugar signaling and the cellular energy status are likely to communicate with each other and influence anaerobic induction of gene expression in rice. We also studied the cellular changes induced by energy deficit conditions. For example, central vacuolation is one of the most striking cellular changes occurring in rice cells upon energy starved conditions. Anaerobic conditions also induces rice hexokinase 7 gene (OsHxk7) expression by releasing the sugar repression of this gene, and enhanced expression of this gene apparently improved the survivability of rice cells under anaerobic conditions. We believe that the increase in glycolytic flux mediated by anaerobically induced OsHxk7 would contribute to the resistance of rice cells to submergence. We have also uncovered the fact that the tonoplast intrinsic protein(s) is involved in maintenance of vacuolar structure in cereal seeds, thereby,
invoking the further deep study of this exceptionally abundant protein in vacuolar membrane. Take together, interactions between various signaling pathways appears to be involved in maintaining the energenic hemeostasis in rice under anaerobic conditions.