Morphological Characterization,Genetic Analysis And Molecular Tagging Of Genes For A Rice Mutant With Abnormal Hull

Rice (Oryza sativa L) is not only one of the most important food crops in the world, butalso a model plant for study of the molecular developmental biology in monocots. Studieson the rice reproductive organ mechanisms will be significant in theory and in practice.Now over 70 homeotic genes have been cloned from rice by using the conserved sequencesof the homeotic genes of dicots as probe screening the rice genomic library or cDNA.Because homeotic gene mutation and floral organ variation is a direct relationship,therefore the mutant application is the current functional genomics study developmentdirection. We discovered one mutant ah(abnormal hull) from line 458, which was a line ofthe twin-seedling strain W2555.ln this study, we have investigated the morphogenesisprogress, genetic analysis of mutant traits and molecular tagging of related gene. Themajor results are summarized as follows:1. The investigation of the floral morphogenesis: Compared with the wild type, the matureah flowers had sparse branches and decreased number of florets from the base to thepeak. Frequently, the florets at the top of the panicle did not develop completely. Theunderdeveloped florets often showed slender and white in their life cycle. The florets ofmutant showed degenerated lemma and palea. Stamens and lodicules were homeoticlytransformed into pistils and palea/lemma-like structures, respectively. It seemed that ahmutant phenotypes of the homeotic conversions in lodicules and stamens were verysimilar with that of the B loss-of-function spwl gene reported previously in rice.2. Genetic analysis of ah mutant: Three F₂ populations, Shuhui527/ah, 93-11/ah andNipponbare/ah were developed. The results of the genetic analysis showed that the traitsof the ah mutant are controlled by a single recessive gene.3. Molecular tagging of gene of ah mutant: The F₂ population, derived from 93-11/ah, wasused to screen molecular markers linked with ah gene. Subsequently, the gene wasmapped between two restriction fragment length polymorphism markers, RM463 and RM17 on chromosome 12, with distances of 8.3cM and 13.5cM, This gene istemporarily designated as ah.