| Rice is one of the important food crop in the world, increasing its production is strategic significance to guarantee our country food security. Rice ideotype is the base of the high yield formation. Tillering and panicle number are key agronomic traits in rice, playing essential roles in shaping plant architecture. At present, gene cloning related to tiller in rice mainly depend on mutants, few QTLs for rice tillering has been cloned and characterized. Previously, we fine-mapped a major QTL, qPN1, regulating rice panicle number using a chromosome segment substitution line derived from Nipponbare and Guangluai 4. LOC_Os01g70550 was pretented to be the candidate gene for qPN1. In this study, we carried out transgenic analysis to confirm the candidate. The main results are as follows:1.BLAST analysis showed that, qPN1 encoded HGSNAT protein, containing 10 transmembrane domains. A phylogenetic tree analysis showed qPN1 was highly conserved in evolution.2.We constructed qPN1 RNAi vector, transferred the vector into 9311 and achieved T3-generation transgenic seedlings, gene expression analysis and agronomic study showed that qPNl expression level was knocked down and plant height of interference lines ware reduced by 31.0% and 36.2% respectively, and panicle number were reduced by 12.4% and 23.8% respectively. The biological mass and grain yield per plant were also significantly reduced.3. The overexpression transgenic plants of qPNl were also be generated. The individuals with enhanced expression levels of qPN1 exhibited higher plant height. Furthermore, overexpression of qPN1 in Arabidopsis also leads to increased plant height and biomass.4. We screened and obtained a TOS17 insertion mutant of qPN1, NE8547, from the Japanese rice TOS17 mutant library. Molecular identification showed that the TOS17 was inserted in the 8th intron, but caused down-regulation of qPN1. Compared with wild type, the plant height and panicle number per plant of NE8547 mutant were reduced by 31.5% and 20.9% respectively. And the biomass and grain yield were also significantly reduced. This result indicated that, LOC_Os01g70550 was the target gene of qPN1.5. Expression analysis showed that qPN1 constitutively expresses in stems, roots, leaves, flowers and other tissues. Transient expression of 35S-qPN1-GFP fusion protein in rice protoplasts showed that qPN1 protein is a membrane protein, which is coincided with the structure of qPN1 protein containing 10 transmembrane domains. |
