The Fine Mapping Of A Hull Mutant In Rice

Based on the research of floral organ of dicotyledonous model plant, such as Arabidopsis thaliana and Antirrhinum majus, we have already known the genetic mechanism of some plants flower development, and ABCE Model which relating to floral organ homologous genes regulation pattern was established. Oryza Sativa, one of the monocotyledon plants, whose floral organ is different from the dicotyledonous plant. The floral organ of rice is consisted by one lemma, one palea, two lodicules, six stamens and one pistil from outside in. It has stamens and pistil with similar to dicotyledon, but no obvious sepal and petal in monocotyledon. Though, some research have showed that it is basically applicable to ABCE model, we still do not understand the regulated mechanism of the development of its outer two floral organs yet. Rice is one of the world’s important food crops, but also representative of monocots. Its floral organ formation and development is closely related to production and quality, so this study is significant.We have found a rice mutant on hull in our rice mutant. library. Its hull is narrow and long and the tip of the lemma is severely bent toward to the palea, like a hook. But the occlusion of lemma and palea is normal and the development of inner floral organs is normal too. There is not much difference in other traits such as plant height and tiller number with Nipponbare. We named it slender hull1(shl) temporarily. Genetic analysis showed that the target character is controlled by a single recessive gene. In this study, we fine mapped SHI gene through map-based cloning, and we did gene prediction and functional complementation experiments on this basis.The following main conclusions:(1)Paraffin section of the cross-section of the glume showed that glume cell morphology and composition is no different from wild-type, and the occlusion of lemma and palea is normal.(2)We hybridize sh1with TN1. In the F2population we Selected124recessive trait plants to do the initial location, and the position is on chromosome1between the SSR markers RM3148and RM3740. The genetic distance is5.6cM and12.5cM respectively. Then, we enlarged the location population and do fine mapping. Finally, SHI was located to a92kb region by using some public markers and8pairs STS markers designed by ourselves which seated in initial location region. We analysis the interval showed that there are11open reading frames(ORFs), and finally select the zinc finger protein gene as a candidate gene.(3)Seqencing shl and the other parent. Candidate gene sequencing results showed that shl have a single base difference in the exon region of the gene with others(sh1:T; others: C). This change cause missense mutation(sh1:Val; other parents:Ala).At present, the function complementary experiment of shl is in progress. The gene we predicted is OsJAG actually. OsJAG in rice and its homologous genes in other species have been reported. Their main function is regulating floral organ development in plants.