Genetic Analysis And Fine Mapping Of An Abnormal Glume And Multi-pistil Mutant In Rice

Rice is one of the most important food crops in the world. It is essential to further increase the rice yield for solving the world food supplies problem. The process of flowering controls the reproductive phase of rice and is correlated with the yield and quality directly. Consequently, focusing on the development of flower will greatly contribute to rice breeding. We used a loss-of-function mutant of OsJAG, which originated from anther-culture progeny of autotetraploid rice, as material to isolate the gene through map-based cloning and made predicts for its function. The important results are as follows:1. The Phenotype comparisons between abnormal glume and multi-pistil mutant (AGMP)and wild-type (wt) showed that the mutant exhibited a decrease in stamen number, and an increase in the number of carpels, which resulted in most pistils and stamens sterile. The results observed from SEM showed that the paleas elongated outside the lemma. The narrow glumes cannot enclose inner floral organs i.e. stamens and pistil. Genetics analysis showed that the mutant was still decided by single recessive nuclear gene.2. To map the mutant gene, we generated F2 mapping population of ITA182×mutant. After roughly mapped the gene to the region flanked by two markers RM10073 and RM6324 of chromosome 1 short arm respectively, we further narrowed the interval to about 42 kb which included four annotated genes, namely one retrotransposon protein, one JAG expressed protein, one hypothetical protein and one conserved hypothetical protein, respectively. The JAG protein was firstly reported in Arabidopsis with one single zinc-finger of C2H2 type and is involved in the development of lateral organs. This annotated gene is an orthologue of AtJAG and is named OsJAG. So we take OsJAG as the candidate gene.3. The results from sequencing the mutant target gene revealed that one point mutation present in the OsJAG, which changed the codon of UGC to UGA and would cause premature termination during the mRNA translation. The C2H2 type zinc-finger was lost and the transcription factor lost its activity. Consequently, we choose the OsJAG as the strong candidate of AGMP.