The Screening Of Rice RNAi Library And Functional Analysis Of OsEXO-Like

Rice is a very important grain crop in our country，it’s irreplaceable to research on the function ofgenes of it. To gain yield in unit area，modern techniques of molecular biology and traditional breedingstrategy should be combined. Mutants are crucial materials for rice functional genomics research. Byconstructing the mutant library and using biotechnology to isolate and identification the function ofgenes has become the dominating means of gene function for rice in the world. In modern breedingstrategy，one of the crucial standards of rice is plant shape while the height，effective tiller number，theangle of tillers，the width and the angle of leaves is the main factors determined the plant shape.Here we identification about6000rice transgenic RNAi mutant，which come from the RNAilibrary based on rolling-circle amplification (RCA)-mediated hpRNA (RMHR) constructionsystem.Meanwhile，we found a novel of dwarf and leaves erect mutant derived from the RNAi mutantlibrary，the target gene of the mutant is Os02g0756800which function was unknown in rice. Theorthology in Arabidopsis thaliana is AT4G08950（EXORDIUM）. By using these two kinds of mutant toanalyse the function of EXO in rice.The main conclusions are as follows:1) Using quantitative RT-PCR analysis the transcription level of target gene and Northern blottingdetection the generation of siRNA we conformed that the RNAi vector functioned in transgenicplants, and the transgenic rice with varied phenotype of unknown function of gene. In addition，RNAi vector is also effective to the gene family or multi-copy genes. The stability between thedifferent lines with the same hpRNA is well, and the phenotype between these transgenic lines issimilar.2) OsEXO-like belongs to PHI1protein family.There are12members in rice.The EXO-like mainlyexpressed in leaves，reached it’s maximum level in adult stage.3) The OsEXO-like mutant shows BR-related phenotype，Ei (RNAi-EXO) is dwarf,leaves erect,shorter leaves，few fertility,spikelet number per panicle is decreased. The panicle of Ei are nearlyerect or slightly bending even the rice is maturity. Eo（Overexpression-EXO）mutants have theenlarged leaves and early flowering. BRs would promote the expression of EXO-like.Analysis theresults of gene chip, Cytochrome P450famuly protein showed significantly weaker expression inthe RNAi mutant than WT plants,induced CYP51G1and DWARF4,illustrate EXO-like is in the BRsignal transduction patyway.4) Compare with the wild type the of withness of Eo（Overexpression-EXO）increased20%, andthe Ei (RNAi-EXO) decreased15%.By using SEM observed the flag leaf in jointing stage，weconformed the decreased size of leaf is caused by reduced cell size.5) Gene chip and quantitative RT-PCR analysis of leaves material identified genes which revealedEXO-dependent expression. Some genes involved in synthesis cell wall composition ormetabolism showed a weaker expression in Ei compare with WT, such as F5H/1.11.1.7,Class III chitinase RCB4and Xip1. The OsEXO-like gene.OsEXO presumably is through modulating thesynthesis and metabolism of cell wall affects the growth of plant leaves.