Establishment Of Rice Few-tillering Mutant NILs And The Genome-wide Expression Profile Analysis

Rice is one of the major human beings' food resources in the world. Tillering in rice (Oryza sativa L.) is an important agronomic trait that determines grain production, and the tiller number should be moderate in super-rice. As a specific kind of branching in monocotyledonous plants, rice tillering is also of developmental importance. Though the molecular mechanism of rice tillering was already considerably broken through, the signal pass way was known a little, needing to be studied further. In this study, near isogenic lines (NILs), 02428-ft1 (between G069 and 02428), was established, microscopic studies on rice tiller bud formation were carried out and gene expression profile analysis was done by using microarray technology. The main results obtained in this study are summarized in the following portions.1. G069, a few-tillering rice mutant, was identified from the anther culture progeny of an indica-japonnica hybrid combination, Gui630/02428. And the NILs, 02428-ft1 (between G069 and 02428), was established by using 02428 as back crossing parent to continuously back-cross with 02428-ft1 and the few-tillering plants of F2 populations. Several mutant traits expressed in the mutant NIL, such as few-tillering, delayed tillering development, yellowing apex and margin of early leaves, enhancing the ability of re-generation, dwarf, and so on.2. Cytology study was carded out through the paraffin section essay. The lateral medstem number of the mutant was fewer and smaller in appearance, the number of lateral medstem was decreased and the speed of its initiation was slowed down. These results confirmed that ft1 could inhibit the lateral medstem initiation in rice partly.3. Rice 57K GeneChip (Affymetrix) was used to compare the gene expression profiling between 02428-ft1 and 02428 in transcriptomics level. 136 different expression genes were found, 61 of them were up-regulated and the remaining genes were down-regulated in 02428-ft1. Among the 136 genes, 27 genes were only detectable in 02428-ft1 because of activation and 30 genes were only detectable in 02428 because of silence.4. The function of the differently expressed genes was predicted by using on-line analysis systems of Affymetrix, NCBI and TIGR. Through this analysis, the function of the differently expressed genes was proved to be extensive, acting as transcription factor, kinase, function protein, regulatory protein and so on, but part of the genes' function was unknown. Several genes were known as related to branching in plant, such as LOB, F-box domain and NAM. Moreover, the chloroplast genome and the mitochondrion genome were down-regulated and up-regulated respectively. All of these results indicated that tillering in rice was a complicated life-process controlled by many genes.5. The function of the differently expressed genes was categorized according to molecular function, biological process and cellular structure respectively. In molecular function level, the genes with catalytic and binding activity changed mostly, and they will seriously change the biological process with a tiny amount. Sophisticated changes took place in the biological process level, genes with cell physiological functions, cell growth or maintenance and metabolism changed mostly, others such as physiological-regulated gene, stress reaction gene changed, too. In cell structure level, intracellular cytoplasm changed mostly.