Genetic Transformation And Function Of Rice OsRACK1

As a member of WD repeat-containing family of proteins, RACK1 was frist discovered in animals. RACK1 is skeleton protein in mammals. As a highly conserved cellular adapter protein, RACK1 is involved in multiple signaling pathways. In addition to binding with PKC, RACK1 plays crucial role in protein translation, tissue development, circadian clock, neural responses and tumorigenesis in mammals. In plant, RACK1 is involved in several growth and development processes which include plant hormone signaling pathways, leaf and root development, drought and salt stress responses, flooding stress, seed germination, synthesis of H2O2, innate immunity, plant response to fungal pathogens, association with ribosomes, protein translation and miRNA abundance. Even though A. thaliana has been used traditionally as a plant model and research on RACK1 has been carried out in this species. Since the functions of RACKl are different in various species and tissues, we should study the functions of RACK1 in different plants. In this study, we cloned OsRACK1A and OsRACK1B genes of Oryza Sativa and constructed transgenic plants with a fluorescent label. The major results are as follows:1. The OsRACK1A-eGFP and OsRACK1B-eGFP overexpression transgenic seedlings of T1 generation was identific by Basta, western blot, qRT-PCR and detection of green fluorescent protein by laser scanning confocal microscopy. It has been confirmed that we constructed the OsRACK1A-eGFP and OsRACK1 B-eGFP overexpressing transgenic lines. Also we found that OsRACK1A and OsRACK1B scattered in whole cell through observing the subcellular localization of green fluorescent protein labeling by laser confocal microscopy.2. The expression of OsRACK1A in grain development of wild type rice analysis shows that RACK1A continued accumulating during the rice grain development process, and its accumulation amount was very large. It was inferred that OsRACK1A plays a very important role in rice grain development or germination processes. What’s more, we consumed that OsRACK1A might not have direct link with starch structures.3. The heading time of OsRACK1A interference lines, overexpression lines and wild type rice are different. OsRACK1A interference transgenic lines heading frist, wild-type heading followed, OsRACK1A overexpressing lines heading finally. Interference lines heading earlier than overexpressed lines by at least 10 days. The results shows, RACK1 A may reverse regulation rice heading.4. The mRNA expression of OsRACK1A gene was also significantly down-regulated under salt stress, however, the expression of the protein has increased. Phenotypic analysis under salt stress shows, the OsRACK1A interference seedlings is strong than wild-type and overexpression lines.Above all, we did some studys on the function of OsRACK1A in salt stress, grain development and heading stage. We also constructed transgenic plants as materials for the further study of OsRACK1 signaling pathways in rice.