초록 ▼

Ⅳ. 연구개발결과
본 연구를 통하여 애기장대 엽록체에서 식물의 광합성 작용에 필수적인 전자전달 매개체이며 스트레스 환경에서 항산화제로서 중요한 역할을 수행하는 PQ-9의 합성에 FBN5가 반드시 필요함을 증명하였다. 현재까지 해외 다른 팀의 연구를 통하여 PQ-9의 합성에 관여하는 효소들은 잘 규명되었다. 그러나 본 연구를 통하여 PQ-9의 합성은 효소들의 작용만으로 이루어지는 것이 아니라, 엽록체지질결합단백질인 FBN5와 SPS 효소와의 상호작용이 필요함을 제시하였다.
레스퀘렐라 종자에는 산업기능성인 하이드록시지방산을

Ⅳ. 연구개발결과
본 연구를 통하여 애기장대 엽록체에서 식물의 광합성 작용에 필수적인 전자전달 매개체이며 스트레스 환경에서 항산화제로서 중요한 역할을 수행하는 PQ-9의 합성에 FBN5가 반드시 필요함을 증명하였다. 현재까지 해외 다른 팀의 연구를 통하여 PQ-9의 합성에 관여하는 효소들은 잘 규명되었다. 그러나 본 연구를 통하여 PQ-9의 합성은 효소들의 작용만으로 이루어지는 것이 아니라, 엽록체지질결합단백질인 FBN5와 SPS 효소와의 상호작용이 필요함을 제시하였다.
레스퀘렐라 종자에는 산업기능성인 하이드록시지방산을 생산한다. 종자의 전사체를 대량 분석하여 종자 지방합성 대사를 이해하고 하이드록시지방산 합성에 관여하는 유전자들을 분리하고자 하였다. 종자 전사체분석을 위해 651 mega-base의 염기서열을 생산하여 26,995의 unique 유전자의 발현을 확인하였다. 74%에 해당하는 19,861 유전자가 기존에 보고된 유전자들과 상동성을 보였다. 레스퀘렐라 지방합성 대사에 관여하는 유전자들의 분석을 통해 레스퀘렐라가 어떻게 하이드록시지방산을 종자에서 합성하는지 대사를 유전자 수준에서 정리할 수 있었다(Fig. 9). 본 연구에서 밝힌 하이드록시지방산 생산대사와 발견한 지방합성 유전자들은 하이드록시지방산 생산 작물개발에 유용한 재료를 제공한다.

Abstract ▼

Fibrillins are lipid-associated proteins in plastids and are ubiquitous in plants. Fibrillins are known to accumulate and sequester carotenoids in chromoplasts during the development of flowers and fruits; however, little is known about the function of fibrillins in leaf tissues. Here we identified

Fibrillins are lipid-associated proteins in plastids and are ubiquitous in plants. Fibrillins are known to accumulate and sequester carotenoids in chromoplasts during the development of flowers and fruits; however, little is known about the function of fibrillins in leaf tissues. Here we identified a novel protein fibrillin5 (FBN5) that is essential for plastoquinone-9 (PQ-9) biosynthesis in Arabidopsis thaliana. We showed that homozygous fbn5-1 plants were seedling-lethal, and XVE:FBN5-B transgenic plants expressing low levels of FBN5-B showed a lower growth rate and were smaller than wild-type. In chloroplasts, FBN5-B physically interacts with solanesyl-diphosphate synthase (SPS) 1 and 2, which synthesize the solanesyl moiety of PQ-9. Plants containing defective FBN5-B accumulated less PQ-9 and its cyclized product, plastochromanol-8, which is consistent with mutant phenotypes showing lower photosynthetic performance and higher levels of hydrogen peroxide. The role of FBN5-B in the FBN5-B/dimeric SPS complex is discussed with respect to biosynthesis of the solanesyl moiety.
Castor oil is the only commercial source of hydroxy fatty acid that has industrial value. The production of castor oil is hampered by the presence of the toxin ricin in its seed. Lesquerella seed also accumulates hydroxy fatty acid and is free of ricin, and thus it is being developed as a new crop for hydroxy fatty acid production. A high-throughput, large-scale sequencing of transcripts from developing lesquerella seeds was carried out by 454 pyrosequencing to generate a database for quality improvement of seed oil and other agronomic traits. Deep mining and characterization of acyl-lipid genes were conducted to uncover candidate genes for further studies of mechanisms underlying hydroxy fatty acid and seed oil synthesis. A total of 651 megabases of raw sequences from an mRNA sample of developing seeds was acquired. Bioinformatic analysis of these sequences revealed 59,914 transcripts representing 26,995 unique genes that include nearly all known seed expressed genes. Based on sequence similarity with known plant proteins, about 74% (19,861) genes matched with annotated coding genes. Among them, 95% (18,868) showed highest sequence homology with Arabidopsis genes, which will allow translation of genomics and genetics findings from Arabidopsis to lesquerella. Using Arabidopsis acyl-lipid genes as queries, we searched the transcriptome assembly and identified 615 lesquerella genes involved in all known pathways of acyl-lipid metabolism. Further deep mining the transcriptome assembly led to identification of almost all lesquerella genes involved in fatty acid and triacylglycerol synthesis. Moreover, we characterized the spatial and temporal expression profiles of 15 key genes using the quantitative PCR assay. We have built a lesquerella seed transcriptome that provides a valuable reference in addition to the castor database for discovering genes involved in the synthesis of triacylglycerols enriched with hydroxy fatty acids. The information obtained from data mining and gene expression profiling will provide a resource not only for the study of hydroxy fatty acid metabolism, but also for the biotechnological production of hydroxy fatty acids in existing oilseed crops.