Molecular Mapping Of Narrow Leaf Gene Nal8in Rice

Rice is one of the most important crops all over the world. It is also a model plant of genetics and monocot developmental biology. At the same time its leaves are the primary organs of photosynthesis and respiration. Their color, type and size could affect plant types and photosynthesis directly, output and quality of rice also be influenced consequently. Now days studying of leaves are one of the common focuses of breeders, geneticists and molecular biologists. Meanwhile researching of leaf development pattern is one of most important component.Two important parts of leaf developing are initiation of rice leaf primordium and establishment of leaf polarity. Following the leaf formed along the axes, there are three different axes proximal-distal axis, daxial-abaxial axis and left-right axis. Recently, several molecular patterns are provided to explain processes of proximal-distal axis and daxial-abaxial axis developing. However none convincing pattern could be used to describe the development of left-right axis clearly till now. Therefore it is useful and practical to research the process of left-right axis developing of rice leaf.In present study, two narrow leaf mutants, designated as narrow leaf8-1(nal8-1) and narrow leaf8-2(nal8-2), were derived from the indica cultivar9311, radiated by60Co-γ ray. Map-based cloning and RT-PCR methods were used for mapping this gene.The results as followed1. Compared with wide type (WT)9311, many agronomic traits of nal8are changed, such as leaves of nal8are significantly narrowed, plant height turns lower, tiller number increased, setting percentage and thousand seed weight decreased, rachis, inverted Ⅱ, inverted Ⅲ, inverted IV internodes of nal8-1are much shorter. Rachis and spike length are much shorter, no significant changes of inverted Ⅱ and inverted Ⅳ internodes, however, inverted Ⅲ turns longer.2. nal8mutant was crossed to a japonica cultivar9516, the phenotype of F1plants were normal, and the ratio of normal plants to mutant plants in F2nal8/9516 population was fitted to the Mendelian ratio3:1, suggesting the phenotype of narrow leaf mutant was controlled by a recessive gene.3. Crossing between nal8-1and nal8-2, the phenotype of F1plants were narrow leaf, suggesting they are alleles.4. nal8mutant was crossed to a japonica cultivar9516, and Zhonghua11, F2were used as mapping populations,5877individuals of narrow leaf were collected.22narrow leaf individuals were used for preliminary mapping. nal8was located on chromosome7linked to SSR marker RM234. Then used STS and CAPS markers for map-based cloning, finally located nal8between STS markers X54and X38, about200kb.5.3BAC are included on this200kb and there are32predicted genes,27of them are function genes. RT-PCR primers of parts function genes were designed for RT-PCR. Then some of expression changed genes were sequenced, however there are no sequence differences of CDS between WT and nal8mutants.