Identification of quantitative trait loci affecting tolerance to low phosphorus in rice (Oryza Sativa L.)

Phosphorus (P)-deficiency in rice (Oryza. Sativa. L) may cause yield reductions. This research has been conducted to map quantitative trait loci (QTLs) for tolerance to low phosphorus stress in a doubled haploid (DH) population. By using the linkage map of this population, the QTLs for relative dry weight, relative P content and relative P utilization efficiency have been located. The results indicate that one RFLP marker located on chromosome 6 is closely associated with relative root dry weight, relative shoot dry weight and relative total dry weight, which explain 24.9%, 20.5% and 25.2% of the total phenotypic variations, respectively. Two QTLs affect relative P uptake content, which account for 20.7% of the total phenotypic variations. One micro-effect QTL has been found to be associated with relative P utilization efficiency. It is suggested that the P uptake efficiency is more associated with P efficiency. Among the secondary physiological indices of P uptake efficiency, the root dry weight is more important than others.     

控制水稻剑叶形态相关性状的数量基因位点(QTL)的定位

水稻籽粒中一半以上的碳水化合物来自剑叶的光合作用,剑叶形态改良一直是水稻株型育种的一个重要目标．利用一个日本主要种植的粳稻品种越光（轮回亲本）和一个印度的籼稻品种Kasalath杂交产生的回交重组自交系群体（backcross recombinant inbred lines,BILs）对剑叶形态中的3个主要性状（剑叶长、叶宽以及其叶面积）进行了相关分析及其数量基因位点（quantitative trait loci,QTL）的定位．研究表明,控制剑叶形态的3个主要性状间存在极显著的正相关,并检测到影响3个性状的8个QTL,分布在第1,3,4,6条染色体上,贡献率介于4．94％～22．07％,其中第4染色体上C1016标记和第6染色体上C556标记附近的共有6个QTL,其两侧的紧密分子标记在水稻株型分子育种上具有一定应用价值．     

水稻芒长及其分布特征相关QTL的定位

水稻芒的性状与驯化过程密切相关,具体表现为芒长短和芒的分布等．利用一个无芒品种越光（轮回亲本）和一个有芒品种Kasalath杂交产生的回交重组自交系群体,在上海、海南两地对芒长和芒的分布（芒出现比例）进行了相关分析及其相关基因（QTL）定位,结果发现这两个性状间存在显著的正相关．共检测到影响这两个性状的12个QTL,分布在6条染色体上的7个区域,贡献率介于2．90％-53．24％,其正效应大多来自有芒亲本Kasalath,但也有3个QTL正效应来自无芒亲本越光,并对这个现象产生的原因进行了讨论．本研究检测到的QTL及其两侧的分子标记可以用于水稻驯化的研究和理想型无芒品种分子辅助育种．     

Identification of salt-tolerance QTL in rice (Oryza sativa L.)

Quantitative trait loci (QTLs) controlling salt-tolerance at the seedling stage in rice (Oryza sativa L.) were identified by interval mapping (SIM) and composite interval mapping (CIM) using a doubled haploid population ZJDH and its high resolution genetic linkage map. The population was derived from an inter-subspecific cross between an indica variety Zhaiyeqing8 (ZYQ8) and a japonica variety Jingxi17 (JX17). Analysis of survival days of seedlings treated with 0.7% NaCI revealed that a major salt-tolerance quantitative trait locus (QTL), Std, was present between markers RG612 and C131 on chromosome 1 when using both MAPMAKER/QTL 1.1 and PLABQTL 1.0 (SIM). Its allele which contributes to salt-tolerance was from ZYQ8. In addition, seven more QTLs which give additive effect on salt-tolerance are identified when using PLABQTL (CIM), and most of them were from JX17.     

Fine mapping of locus S-b for F1 pollen sterility in rice （Oryza sativa L.）

Strong heterosis existed in the hybrid of the subspe-cies in rice[1,2]. However, the partial sterility of the hy-brid hinders the utilization of the heterosis[3,4]. Ikehashi et al.[5,6] considered the female gamete as the main ste-rility form and proposed…     

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.     

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 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.     

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.     

Origin of the Chinese cultivated rice (Oryza sativa L.)

The following new research progresses are summarized and discussed, which are related to 3 main problems in origin of rice cultivation in China: 1. new hypothesis of rice cultivation in China— middle Yangtze River and upper Huai River regions; 2. primitive cultivated rice and the strengthen period of domestication; 3. genetic diversity centers of cultivated rice in China; 4. China and South Asia might be two independent systems of origin and differentiation of Asian cultivated rice; 5. morphological classification of common wild rice of China; 6. primitive progenitor of common wild rice; 7. direct progenitor of cultivated rice; 8. present or not the annual wild rice in China; 9. differentiation or not the common wild rice into Indica and Japonica; 10. origin and differentiation of Indica and Japonica.     

Identification and mapping of quantitative trait loci controlling cold-tolerance of Chinese common with rice （O.rufipogon Griff.） at booting to flowering stages

An advanced backcross population of rice was used to identify the quantitative trait locus(QTL) controlling the cold-tolerance at booting to flowering stages.The recipient,Guichao 2(GC2),was a commercial Indica rice;the donor Dongxiang common wild rice,was an accession of common wild rice(DXCWR,Oryza rufipogon Griff.).Three QTLs for cold-tolerance were detected on chromosomes 1,6 and 11.Two of them coming from DXCWR could enhance the cold-tolerance of the backcross progenies.Moreover,one sterility QTL that could reduce the seed set rate of the backcross progenies by 78% was mapped on chromosome5.     

高蛋白籼稻品系H12体细胞无性系变异的研究

以高蛋白籼稻品系H12及其体细胞无性系HE1297、H28、H17、HE10和H1701为材料,进行了无性系变异的研究。结果表明：高蛋白无性系的变异在遗传上具有稳定性,其中千粒重等部分性状的稳定性和整齐度超过了亲本;变异主要在数量性状,与蛋白质含量性状连锁的有株主同、有效分蘖数、直链淀粉、千粒重、粒长等性状,变异方向既有同向也有反向;存在隐性变异,出现了1个糯稻品系H1701;花药培养力的变异非常明显,H12的花药培养力极低,大多数无性系的花药培养力有显著提高。     

Identification and mapping of quantitative trait loci controlling cold-tolerance of Chinese common wild rice (O. rufipogon Griff.) at booting to flowering stages

Cold injury is an important limitation of rice production. Therefore, screening for cold-tolerant genetic resources and the development of highly cold-tolerant cultivars is crucial for higher yield potential and stable yield of rice. There have been several reports on the genetic analysis and QTL mapping of the cold-tolerance at the booting stage. Toriyama et al.[1,2] and Futsuhara et al.[3,4] reported that 4 or more genes were involved in the cold-tolerance. Several QTLs at the booting sta…     

水稻分子连锁图谱及重要性状的基因定位

对窄叶青８号京系１７的Ｆ１进行花药培养,获得了含有１３２个株系的加倍单倍体群体。     

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.     

用基因枪法转bar基因以培育抗除草剂的直播稻

用基因枪法将 p CB1 质粒 (含 bar基因和 cecropin B基因 )导入到三种有应用前景的直播稻品种中 ,受体材料为来源于水稻未成熟胚的胚性愈伤组织和来源于成熟胚的悬浮细胞系 .当代转化植株显示出很强的对除草剂 Basta的抗性 ,Southern-blot分析显示 :两个外源基因共整合到转化植株基因组中 ;子一代植株中仍含有外源基因 ;来源于同一块愈伤组织的转化植株的整合模式可能是相似的 ,也可能完全不同 .     

Conditional and unconditional mapping of quantitative trait loci underlying plant height and tiller number in rice (Oryza sativa L.) grown at two nitrogen levels

In this study,we used 127 double haploid (DH) lines to analyze agricultural traits of rice.The DH lines,derived from a ZYQ8 (indica)/JX17 (japonica) cross by anther culture,contained 160 RFLP and 83 SSR markers.Unconditional and conditional quantitative trait loci (QTL) mapping was conducted to analyze plant height (PH) and tillers per plant (TP) at five growth stages that were grown at two nitrogen levels.Fourteen PH and 13 TP unconditional QTL were identified in the different growth stages,including 19 QTL from high-nitrogen (HN) and 14 QTL from low-nitrogen (LN) conditions.The conditional QTL for 14 genomic regions under LN/HN con-ditions showed that there was a significant effect on PH and TP across the different stages.Only one conditional QTL,ph2-3,was unable to be detected in unconditional mapping.More QTL were detected in the first four rice growth stages than in the final stage.Further-more,a line from the DH mapping population,DH78,was identified in extreme phenotypes of PH and TP that exhibited dwarfism and less-tiller (dft) characters.The gene dftl was mapped to chromosome 2 using a backcrossed population of DH78/JX17 through a map-based cloning strategy.The location of dftl coincided with the mapping region of the small-LOD peak,QTL ph2 and tp2,which were identified in plants grown in low-nitrogen conditions.Further backcrossing and fine-mapping successfully delimited the dftl locus to a 91 kb region.     

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.