Identification and gene mapping of a narrow and upper-albino leaf mutant in rice (Oryza sativa L.)

The leaf blade consists of color and shape traits. Studies of leaf-blade development are important for improvement of rice yield and quality because it is an essential organ for photosynthesis. A narrow and upper-albino leaf mutant (nul1) was identified from among progeny of the indica restorer line Jinhui10 raised from seeds treated with ethyl methane sulfonate. Under field conditions, the mutant displayed narrow and upper-albino leaf blades with significantly decreased photosynthetic pigment contents throughout their development. The narrow-leaf trait is caused by a decreased number of small veins. In contrast to the wild type, the growth period was extended by approximately 8 d and agronomic traits, such as effective panicle number, percentage seed set and 1000-grain weight, declined significantly in the nul1 mutant. Genetic analysis suggested that the narrow and upper-albino leaf characteristics showed coseparation and were controlled by one recessive gene. The Nul1 gene was mapped onto chromosome 7 between the Indel marker Ind07-1 and the Simple Sequence Repeat marker RM21637. The physical distance between the markers was 75 kb and eight genes were annotated in this region based on the rice Nipponbare genome sequence. These results provide a foundation for cloning and function analysis of Nul1.     

Genetic analysis and molecular mapping of a presenescing leaf gene psl1 in rice (Oryza sativa L.)

A rice psl1 (presenescing leaf) mutant was obtained from a japonica variety Zhonghua 11 via radiation of 60Co-γ in M2 generation. Every leaf of the mutant began to wither after it reached the big-gest length,while the leaves of the wild variety could keep green for 25―35 d. In this study,genetic analysis and gene mapping were carried out for the mutant identified. The SSR marker analysis showed that the mutant was controlled by a single recessive gene (psl1) located on chromosome 2. Fine mapping of the psl1 locus was conducted with 34 new STS markers developed around psl1 anchored region based on the sequence diversity between Nippon-bare and 93-11. The psl1 was further mapped be-tween two STS markers,STS2-19 and STS2-26,with genetic distances of 0.43 and 0.11 cM,respectively,while cosegregated with STS2-25. A BAC contig was found to span the psl1 locus,the region being delim-ited to 48 kb. This result was very useful for cloning of the psl1 gene.     

Genetic analysis and molecular mapping of a presenescing leaf gene psll in rice （Oryza sativa L.）

A rice psl1 （presenescing leaf） mutant was obtained from a japonica variety Zhonghua 11 via radiation of ^60Co-γ in M2 generation. Every leaf of the mutant began to wither after it reached the biggest length, while the leaves of the wild variety could keep green for 25--35 d. In this study, genetic analysis and gene mapping were carried out for the mutant identified. The SSR marker analysis showed that the mutant was controlled by a single recessive gene （psl1） located on chromosome 2. Fine mapping of the psl1 locus was conducted with 34 new STS markers developed around psl1 anchored region based on the sequence diversity between Nipponbare and 93-11. The psl1 was further mapped between two STS markers, STS2-19 and STS2-26, with genetic distances of 0.43 and 0.11 cM, respectively, while cosegregated with STS2-25. A BAC contig was found to span the psl1 locus, the region being delimited to 48 kb. This result was very useful for cloning of the psl1 gene.     

Genetic analysis and gene mapping of a narrow leaf mutant in rice ( Oryza sativa L.)

A narrow leaf mutant was obtained after T-DNA transformation conducted on a rice variety Zhonghua 11. Several abnormal morphological characteristics, including semi-dwarf, delayed flowering time, narrow and inward rolling leaves, and lower seed-setting, were observed. The rate of net photosynthesis (under saturate light) of flag leaves in the mutant was significantly lower than that of the wild type. Moreover, the leaf transpiration rate and stomatal conductance in the mutant flag leaf were lower than those of the wild type at the grain filling stage. It was found that the mutant phenotype was not caused by the T-DNA insertion. Genetic analysis showed that the mutant was controlled by a single recessive gene, designated as nal3(t). A genetic linkage map was constructed using a large F₂ mapping population derived from a cross between nal3(t) and an indica variety Longtefu B with 6 polymorphic markers on chromosome 12 identified from 366 SSR markers by the BAS method. Gene nal3(t) was mapped between the markers RM7018 and RM3331. Fine mapping of nal3(t) locus was conducted with 22 newly developed STS markers based on the sequence diversity around the region harboring nal3(t) between Nipponbare and 93–11, and nal3(t) was finally mapped to a 136-kb region between the STS markers NS10 and RH12-8. Supported by National High Technology Research and Development Program of China (863 Program) (Grant No. 2006AA10A102), National Natural Science Foundation of China (Grant No. 30600349) and Natural Science Foundation of Zhejiang Province (Grant No. Y306149)     

Genetic analysis and mapping of rice （Oryza sativa L.） male-sterile （OsMS-L） mutant

A rice male-sterile mutant OsMS-L of japonica cultivar 9522 background, was obtained in M4 population treated with ^60Co γ-Ray. Genetic analysis indicated that the male.sterile phenotype was controlled by a single recessive gene. Results of tissue section showed that at microspore stage, OsMS-L tapetum was retarded. Then tapetal calls expanded and microspores degenerated. No matured pollens were observed in OsMS-L anther locus. To map OsMS-L locus, an F2 population was constructed from the cross between the OsMS-L (japonica) and LongTeFu B(indica). Firstly, the OsMS-L locus was roughly mapped between two SSR markers, RM109 and RM7562 on chromosome 2. And then eleven polymorphic markers were developed for further fine fine-mapping. At last the OsMS-L locus was mapped between the two lnDel markers, Lhsl0 and Lhs6 with genetic distance of 0.4 cM, respectively. The region was delimited to 133 kb. All these results were useful for further cloning and functional analysis of OsMS-L.     

Morphological and physiological analysis of narrow and striped leaf 1 （nsl1） mutant of rice （Oryza sativa L.） and the gene mapping

The shape and color of rice leaves are impor- tant agronomic traits that directly influence the proportion of sunlight energy utilization and ultimately affect the yield and quality. A new mutant exhibiting stable inheritance was identified as derived from ethyl methane sulfonate （EMS）-treated restorer Jinhui 10, tentatively named as narrow and striped leaf 1 （nsll）. The nsll displayed pale white leaves at the seeding stage and then white striped leaves in parallel to the main vein at the jointing stage. Meanwhile, its leaf blades are significantly narrower than the control group of Jinhui 10. The chloroplast structures of cells in the white striped area of the nsll mutant break down, and the photosynthetic pigments are significantly lower than that of the wild type. Moreover, fluorescence parameters, such as Fo, Fv/Fm, ФpsⅡ, qP, and ETR, in the nsll mutant are significantly lower than those of the wild type, and the photosynthetic efficiency is also significantly decreased. These changes in leaf color and shape, together with physiological changes in the nsll, result in smaller plant height and a decrease in the most important agro- nomic traits, such as the number of grains per panicle, grain weight, etc. Genetic analysis shows that the narrow and striped traits of the nsll mutant are controlled by a single recessive nuclear gene, which is located between InDel 16 and InDel 12 in chromosome 3. The physical distance is 204 kb. So far, no similar genes of such leaf color and shape in this area have been reported, This study has laid asolid foundation for the gene cloning and function analysis of NSL 1.     

Genetic analysis and fine mapping of an enclosed panicle mutant esp2 in rice （Oryza sativa L.）

The phenomenon of panicle enclosure in rice is mainly caused by the shortening of uppermost internode.Elucidating the molecular mechanism of panicle enclosure will be helpful for solving the problem of panicle enclosure in male sterile lines and creating new germplasms in rice.We acquired a monogenic recessive enclosed panicle mutant,named as esp2 (enclosed shorter panicle 2),from the tissue culture progeny of indica rice cultivar Minghui-86.In the mutant,panicles were entirely enclosed by flag leaf sheaths and the uppermost internode was almost completely degenerated,but the other internodes did not have obvious changes in length.Genetic analysis indicated that the mutant phenotype was controlled by a recessive gene,which could be steadily inherited and was not affected by genetic background.Apparently,ESP2 is a key gene for the development of uppermost internode in rice.Using an F 2 population of a cross between esp2 and a japonica rice cultivar Xiushui-13 as well as SSR and InDel markers,we fine mapped ESP2 to a 14-kb region on the end of the short arm of chromosome 1.According to the rice genome sequence annotation,only one intact gene exists in this region,namely,a putative phosphatidylserine synthase gene.Sequencing analysis on the mutant and the wild type indicated that this gene was inserted by a 5287-bp retrotransposon sequence.Hence,we took this gene as a candidate of ESP2.The results of this study will facilitate the cloning and functional analysis of ESP2 gene.     

Characterization and mapping of a lesion mimic mutant in rice （Oryza sativa L.）

A rice initiation-type lesion mimic mutant (lmi) was identified, which was isolated from an indica rice Zhongxian 3037 through γ radiation mutagenesis. Trypan blue staining and sterile culture revealed that the mutant spontaneously developed lesions on the leaves in a developmentally regulated and light-dependent manner. Genetic analysis indicated that the lesion mimic trait was controlled by a single resessive locus. Using public molecular markers and an F2 population derived from lmi and 93-11, we mapped the lmi locus to the short arm of chromosome 8, nearby the centromere, between two SSR markers RM547 and RM331. The genetic distance was 1.2 and 3.2 cM, respectively. Then according to the public rice genomic sequence between the two SSR markers, lmi was further finely tagged by three CAPS markers: C4135-8, C4135-9 and C4135-10. And lmi locus was a co-segregated with marker C4135-10, providing a starting point for lmi gene cloning.     

Genetic analysis and fine mapping of the pubescence gene GL6 in rice (Oryza sativa L.)

The pubescence of the leaf blade surface is an important agronomic characteristic for rice morphology and significantly influences rice growth as well as physiological characteristics. This characteristic was analyzed in F1 and F2 plants derived by crossing cultivar 75-1-127 with the indica cultivar Minghui 63, as well as the glabrous cultivar Lemont and indica cultivar 9311. Results indicated that the pubescence of the leaf blade surface was a dominant trait and controlled by a single gene. The GL6 gene was primarily mapped on rice chromosome 6 with recessive F2 population derived from 75-1-127/Minghui 63 by combining bulked segregation analysis and recessive class analysis using the Mapmaker3.0/MapDraw software. The genetic distances between the simple sequence repeat markers RM20491 and RM20547 were 7.2 and 2.2 cM, respectively. The GL6 gene was fine mapped in the interval between InDel-106 and InDel-115 at genetic distances of 0.3 and 0.1 cM, respectively. The large, recessive F2 population was derived from 75-1-127/Minghui 63. A high-resolution genetic and physical map of GL6 was constructed. Derived from the map-based sequences published by the International Rice Genome Sequencing Project, the GL6 gene was localized at an interval of 79 (japonica) and 116.82 kb (9311) bracketed by InDel-106 and InDel-115 within the BAC accession numbers AP008403 and AP005760. Seven annotated genes (japonica) and eight annotated genes (9311) were present. The basis was further set for GL6 cloning and function analysis.     

Genetic analysis and gene mapping of leafy head （lhd）, a mutant blocking the differen-tiation of rachis branches in rice （Oryza sativa L.）

Flowers, fruits and seeds are products of plant re- productive development and provide the important sources of foods for humans. Therefore, the moleculargenetic mechanisms of floral development have been ahotspot of research of plant developmental biology[1]. Rice is one of the most important staple food crops. Theoutcome of its reproductive development would determine the yield and quality of grains. Rice is also a model plantof cereals. Hence, the study of rice reproductivedevelopment, esp…     

Morphology and mapping analysis of rice (Oryza sativa L.) clustered spikelets( Cl) mutant

The rice clustered spikelets (Cl) mutant exhibits a phenotype that most of branch apical have 2-3 spikelets clustered together,SEM (scanning electron microscope )observation suggested that the Cl gene controlled branch apical development,and influenced the terminal spikelets elongation,The spikelet number was reduced in mutant,indicating that Cl may also have an effect on spikelet number,To map Cl locus,two F2 mapping populations derived from the crosses between the Cl and ZhongHua11,and Cl and ZheFu802 were constructed ,respectively,The Cl locus was roughly mapped between two CAPS markers CK0214 and SS0324,A further fine mapping analysis showed that the Cl locus was mapped between makers R0674E and Cl12560,with genetic distances of 0.2 and 2.1 cM,respectively ,Then we found a PAC conting spanning Cl locus,the region was delimited to 196 kb.This results was useful for cloning of the Cl gene,Allelism test demonstrated that Cl was allelic to Cl2 another rice clustered spikelets mutant.     

Fine mapping of an incomplete recessive gene for leaf rolling in rice （Oryza sativa L.）

Genetic analysis and fine mapping of genes controlling leaf rolling were conducted using two backcrossed generations （BC4F2, BC4F3） derived from a cross between QMX, a non-rolled leaf cultivar as a recurrent parent, and JZB, a rolled leaf NIL of ZB as a donor parent. Results indicated that leaf rolling was mainly controlled by an incompletely recessive major gene, namely rl（t）, and at the same time, affected by quantitative trait loci （QTLs） and/or the environment. A genetic linkage map was constructed using MAPMAKER/EXP3.0 with eight polymorphic markers on chromosome 2, which were screened by BAS method from 500 SSR markers and 15 newly developed insertion/deletion （InDel） markers. The position of rl（t） was estimated with composite interval mapping （CIM） method using WinQTLcart2.5. Gene rl（t） was mapped between markers InDel 112 and RM3763, and 1.0 cM away from InDel 112 using 241 plants in BC4F2 population. To fine map r（t）, one BC4F3 line with 855 plants was generated from one semi-rolled leaf plant in BC4F2. Four new polymorphic InDel markers were developed, including InDel 112.6 and InDel 113 located between markers InDe1112 and RM3763. Based on the information of recombination offered by 191 rolled leaf plants and 185 non-rolled leaf plants from the BC4F3 line ,we mapped r（t） to a 137-kb region between markers InDel 112.6 and InDel 113. Homologous gene analysis suggested that r（t）was probably related to the process of leaf development regulated by microRNA.     

Genetic analysis and gene cloning of a triangular hull 1 (tri1) mutant in rice (Oryza sativa L.)

Grain shape and size are two key factors that determine rice yield and quality. In the present study, a rice triangular hull mutant (tri1) was obtained from the progeny of japonica rice variety Taipei 309 treated with 60Co γ-rays. Compared to the wild type, the tri1 mutant presents a triangular hull, and exhibits an increase in grain thickness and protein content, but with a slight decrease in plant height and grain weight. Genetic analysis indicated that the mutant phenotype was controlled by a recessive nuclear gene which is stably inherited. Using a map-based cloning strategy, we fine-mapped tri1 to a 47-kb region between the molecular markers CHR0122 and CHR0127 on the long arm of chromosome 1, and showed that it co-segregates with the molecular marker CHR0119. According to the rice genome sequence annotation there are six predicated genes within the mapped region. Sequencing analysis of the mutant and the wild type indicated that there was a deletion of an A nucleotide in exon 3 of the OsMADS32 gene, which could result in a downstream frameshift mutation and premature termination of the predicted polypeptide. Both semi-quantitative and real-time RT-PCR analyses showed that this gene expressed highly in young inflorescences, while expressed at very low levels in other tissues. These results implied that the OsMADS32 gene could be a candidate of TRI1. Taken together, the results of this study lay the foundation for further investigation into the molecular mechanisms regulating rice caryopsis development.     

Identification of a novel tillering dwarf mutant and fine mapping of the TDDL(T) gene in rice (Oryza sativa L.)

Rice plant architecture is an important agronomic trait that affects the grain yield. To understand the molecular mechanism that controls plant architecture, a tillering dwarf mutant with darker-green leaves derived from an indica cultivar IR64 treated with EMS is characterized. The mutant, designated as tddl(t), is nonallelic to the known tillering dwarf mutants. It is controlled by one recessive nuclear gene, TDDL(T), and grouped into the dn-type dwarfism according to Takeda’s definition. The dwarfism of ...     

Molecular cloning, chromosomal mapping and expression analysis of disease resistance gene homologues in rice (Oryza sativa L.)

Resistance-like sequences have been amplified from first strand cDNA and genomic DNA of rice by PCR using oligonucleotide primers designed from sequence motifs conserved between resistance genes of tobacco andArabidopsis thaliana. 3 PCR clones, designatedOsr1, Osr2 andOsr3 which were 98% identical in nucleotide sequence level, have been found to be significantly homologous to known plant resistance genes and all contained the conserved motifs of NBS-LRR type resistance genes, such as P-loop, kinase2a, kinase3a and transmembrane domain.Southern hybridization revealed that rice resistance gene hornologueswere organized as a cluster in the genome. RFLP mapping using a DH population derived from anindica/japonka cross (Zhaiyeqing 8/Jingxi 17) and an RFLP linkage map assigned two copies ofOsrl and one copy ofOsr3 to the distal position of chromosome 12 where a blast resistance QTL has been mapped previously. Northern blot analysis showed thatOsrl gene was constitutively transcribed in rice leaves, shoots and roots. Further study concerning isolation of full-length cDNAs would be conducive to elucidating the functions of these genes.     

一个新的水稻幼苗黄叶突变体的遗传分析及其基因的初步定位

在60Coγ射线辐照的水稻突变体库中,发现了一个以粳稻品种日本晴为遗传背景的幼苗叶色黄化突变体syl11(seedling yellow leaf 11).与野生型相比,突变体幼苗第二和第三叶表现黄色,在其完全展开之前叶片自其顶端开始转绿,长到四叶期其叶色恢复正常;并且该突变体syl11幼苗黄色叶片光合色素含量明显下降.遗传分析表明,该突变体的遗传性状由1对隐性核基因控制.本研究以培矮64S/syl11的F2代突变型植株作为定位群体,应用微卫星(SSR)分子标记以及新发展的InDel分子标记,将基因syl11定位在水稻第11号染色体长臂上的RM26652和处于着丝粒附近的ID11974分子标记之间,其遗传距离分别为0.5 cM和0.7 cM.     

Genetic basis of heterosis and inbreeding depression in rice （Oryza sativa L.）

The genetic basis of heterosis was studied through mid-parent, standard variety and better parent for 11 quantitative traits in 17 parental lines and their 10 selected hybrids in rice (Oryza sativa L.). The characters were plant height, days to flag leaf initiation, days to first panicle initiation, days to 100% flowering, panicle length, flag leaf length, days to maturity, number of fertile spikelet/panicle, number of effective tillers/hill, grain yield/10-hill, and 1000-grain weight. In general the hybrids performed significantly better than the respective parents. Significant heterosis was observed for most of the studied characters. Among the 10 hybrids, four hybrids viz., 17Ax45R, 25Ax37R, 27Ax39R, 31Ax47R, and 35Ax47R showed highest heterosis in 10-hill grain yield/10-hill. Inbreeding depression of F2 progeny was also studied for 11 characters of 10 hybrids. Both positive and negative inbreeding depression were found in many crosses for the studied characters, but none was found significant. Selection of good parents was found to be the most important for developing high yielding hybrid rice varieties.     

水稻线粒体atp6基因的克隆及其结构分析

以玉米线粒体ａｔｐ６基因为探针所作的Ｓｏｕｔｈｅｒｎ杂文结果显示，水稻野败型细胞质雄性不育系与其保持系（珍汕９７Ａ，Ｂ）的ａｔｐ６基因存在结构上的差异。不育系只有一个ａｔｐ６基因拷贝，而相应的保持系却有两个拷贝．从保持系线粒体ＤＮＡ的Ｌａｍｄａ ＥＭＢＬ３基因文库中筛选出了以上两个ａｔｐ６基因克隆，并根据制作的物理图谱将它们分别定位在２．７５ｋｂ的ＰｓｔＩ／ＰｖｕⅡ和１．６３ｋｂ的Ｓａｌ／ＥｃｏＲ     

Salt tolerance of transgenic rice (Oryza sativa L.) withmtlD gene andgutD gene

Southern blot analysis indicated thatmtlD gene (encoding mannitol-1-phosphate dehydrogenase) andgutD gene (encoding glucitol-6-phosphate dehydrogenase) had been integrated into the rice genome mediated byAgrobacterium tumefaciens LBA4404(pBIGM). The expression of the above two genes in transgenic rice plants was demonstrated by Northern blot analysis and enzymatic activity assay. Analysis of sugar alcohol showed that transgenic rice plants could produce and accumulate mannitol and sorbitol. The salt tolerance of transgenic plants was much higher than that of their controls.