Production of bacterial blight resistant lines from somatic hybridization between Oryza sativa L. and Oryza meyeriana L.

Novel bacterial blight (BB) resistance gene(s) for rice was (were) introduced into a cultivated japonica rice variety Oryza sativa (cv. 8411), via somatic hybridization using the wild rice Oryza meyeriana as the donor of the resistance gene(s). Twenty-nine progenies of somatically hybridized plants were obtained. Seven somatically hybridized plants and their parents were used for AFLP (amplified fragment length polymorphism) analysis using 8 primer pairs. Results confirmed that these plants were somatic hybrids containing the characteristic bands of both parents. The morphology of the regenerated rice showed characters of both O. sativa and O. meyeriana. Two somatic hybrids showed highest BB resistance and the other 8 plants showed moderate resistance. The new germplasms with highest resistance have been used in the rice breeding program for the improvement of bacterial blight resistance.     

Production of bacterial blight resistant lines from somatic hybridization between Oryza sativa L. and Oryza meyeriana L.

Novel bacterial blight (BB) resistance gene(s) for rice was (were) introduced into a cultivated japonica rice variety Oryza sativa (cv. 8411), via somatic hybridization using the wild rice Oryza meyeriana as the donor of the resistance gene(s). Twenty-nine progenies of somatically hybridized plants were obtained. Seven somatically hybridized plants and their parents were used for AFLP (amplified fragment length polymorphism) analysis using 8 primer pairs. Results confirmed that these plants were somatic hybrids containing the characteristic bands of both parents. The morphology of the regenerated rice showed characters of both O. sativa and O. meyeriana. Two somatic hybrids showed highest BB resistance and the other 8 plants showed moderate resistance. The new germplasms with highest resistance have been used in the rice breeding program for the improvement of bacterial blight resistance. Project (No. 98001) supported by Ningbo Agriculture Key Scientific Research Foundation, China     

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

INTRODUCTIONAlthoughriceisanaturallyself-pollinatedcrop,strongheterosisisobservedintheirF1hybrids.HeterosisorhybridvigorismanifestedasimprovedperformanceforF1hybridsgeneratedbycrossingtwoinbredparents.Heterosiscanbedefinedquan-titativelyasanupwarddeviationofthemid-parent,basedonthemeanvaluesofthetwoparents(JohnsonandHutchinson,1993).Heterosismaybepositiveornegative.Dependinguponbreedingob-jectives,bothpositiveandnegativeheterosisareusefulforcropimprovement.Ingeneral,positiveheterosisisd…     

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., 17A×45R, 25A×37R, 27A×39R, 31A×47R, and 35A×47R 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.     

Splicing-site recognition of rice (Oryza sativa L.)DNA sequences

INTRODUCTIONCorrectlypinpointingsplicing sitesingenomicDNAsequencesisnotaneasytask ,whichisofgreatimportancetothegenomeannotationandgenefinding .Intronsaregenerallydividedinto3classes,namelycalssI,classIIandcommonnu cleuspre mRNA .IntronofclassIandIIcango…     

Preliminary study on a gravity-insensitive rice mutant

A gravity-insensitive mutant was isolated from rice (Oryza sativa L. Cv. Zhonghua 11) transformed by Agrobacterium tumefaciens. The mutant's shoot growth (prostrate growth) was insensitive to gravity; whereas root growth displayed a normal positive gravitropism.Histological observation of root caps and leaf sheaths indicated that there was no significant difference in the number and size of amyloplasts in cells of the mutant and cells of the wild type     

Preliminary study on a gravity-insensitive rice mutant

INTRODUCTION The most obvious manifestation of gravitys effect on plants is the downward bending of roots and the upward growth of shoots. Gravity is an important factor in plant development (Barlow, 1995). The starch-statolith hypothesis proposed by Haberlandt and Nmec (Audus, 1962) is the most widely accepted view of how plants perceive gravity. Physiological data suggested that the amyloplast containing starch granules act as the statolith in higher plants. Sedimented amyloplasts ar…     

Splicing-site recognition of rice (Oryza sativa L.)DNA sequences by support vector machines

Motivation: It was found that high accuracy splicing-site recognition of rice (Oryza sativa L.) DNA sequence is especially difficult. We described a new method for the splicing-site recognition of rice DNA sequences. Method: Based on the intron in eukaryotic organisms conforming to the principle of GT-AG, we used support vector machines (SVM) to predict the splicing sites. By machine learning, we built a model and used it to test the effect of the test data set of true and pseudo splicing sites. Results: The prediction accuracy we obtained was 87.53% at the true 5' end splicing site and 87.37% at the true 3' end splicing sites. The results suggested that the SVM approach could achieve higher accuracy than the previous approaches.     

水杨酸对NaCl胁迫下水稻(Oryza Saliva L.)幼苗生理活性的影响

用0．2％水杨酸处理1．2％NaCl胁迫下水稻种子，测定其以下几个生理指标，种子的发芽率，发芽势和幼苗中的酯酶，过氧化氢酶以及抗坏血酸的含量，实验结果显示：外源性水杨酸能够相对提高NaCl胁迫下水稻种子萌发后幼苗的过氧化物酶活性和抗坏血酸的含量，同时也能提高水稻种子的发芽率，发芽势，但对酯酶活性影响不大，研究表明水杨酸能提高水稻种子萌发后幼苗的抗盐性，并使水稻种子出苗整齐，一致。     

A new genetic factor for root gravitropism in rice (Oryza sativa L.)

Root gravitropism is one of the important factors to determine root architecture. To understand the mechanism un-derlying root gravitropism, we isolated a rice (Xiushui63) mutant defective in root gravitropism, designated as glsl. Vertical sections of root caps revealed that glsl mutant displayed normal distribution of amyloplast in the columella cells compared with the wild type. The glsl mutant was less sensitive to 2,4-dichlorophenoxyacetic acid (2,4-D) and a-naphthaleneacetic acid (NAA) than the wild type. Genetic analysis indicated that the phenotype of glsl mutant was caused by a single recessive mutation, which is mapped in a 255-kb region between RM16253 and CAPSI on the short arm of chromosome 4.     

水稻多顺反子质体表达载体的构建

根据发表的水稻叶绿体基因组序列，对比烟草高频同源重组目标区(NCBI编号：X15901)设计引物，用PCR的方法克隆到一段3．939kb叶绿体DNA片段，命名为crDNA．以其作为外源基因定点整合的同源重组片段，以来自烟草叶绿体的强启动子Prm、甘露聚糖酶man、绿荧光蛋白gfp、氨基糖苷3’-腺苷酰基转移酶基因aadA和终止子psbA3’，构建水稻质体多顺反子表达载体pLM3(-psbCPrm—SD-man—SD-gfp-SD-aa-dA—psbA3’-tmm-)．并在大肠杆菌中通过平板定性对所构建载体上的表达盒进行了功能鉴定，结果表明：在大肠杆菌中，多顺反子盒式表达结构中的三个基因(man，gfp，aadA)均得到了表达．     

Two ancient rounds of polyploidy in rice genome

An ancient genome duplication (PPP1) that predates divergence ofthe cereals has recently been recognized. We report here another potentially older large-scale duplication (PPP2) event that predates monocot-dicot divergence in the genome of rice(Oryza saliva L.), as inferred from the age distribution of pairs of duplicate genes based on recent genome data for rice. Our results suggest that paleopolyploidy was widespread and played an important role in the evolution of rice.     

Science Letters:Two ancient rounds of polyploidy in rice genome

An ancient genome duplication (PPP1) that predates divergence of the cereals has recently been recognized. We report here another potentially older large-scale duplication (PPP2) event that predates monocot-dicot divergence in     

Cloning and characterization of a glucose 6-phosphate/phosphate translocator from Oryza sativa

INTRODUCTIONNongreenplastidsofheterotrophictissuesarecarbohydrate importingorganellesand ,inthecaseofamyloplastsofstoragetissues,thesiteofstarchsynthesis.Investigationofwholetissuesfromavarietyofstarchsynthesizingcropplantsindicatedthathexoseunitswereimpo…     

水稻RILs化感作用遗传模型分析

本研究以Lemont（弱化感）和Dular（强化感）水稻杂交产生的重组自交系（recombinent inbred lines,RILs）及其亲本为供体植物,并以稻田主要杂草稗草为受体植物,采用迟播共培法对群体及亲本化感作用进行测定及评价,应用主基因＋多基因分离分析法研究水稻化感作用的遗传体系。结果表明,水稻亲本化感抑草作用差异较大,对受体稗草的根长抑制率呈连续变异,体现出数量性状特征;水稻Lemont（弱化感）×Dular（强化感）组合的Rlhs群体化感作用遗传体系由两对连锁的主基因控制,主基因间的作用方式呈互补作用。进一步估计受体根长抑制率的遗传参数,结果表明,稗草根长抑制率的群体均值m=29．3908245,主基因加性效应与加性×加性上位性互作效应I^＊=7．0619195,主基因遗传率为49．36379％．     

Cloning and characterization of a glucose 6-phosphate/phosphate translocator from Oryza sativa

Plastids of nongreen tissues import carbon as a source of biosynthetic pathways and energy, and glucose 6-phosphate is the preferred hexose phosphate taken up by nongreen plastids. A cDNA clone encoding glucose 6-phosphate/phosphate translocator (GPT) was isolated from a cDNA library of immature seeds of rice and named as OsGPT. The cDNA has one uninterrupted open reading frame encoding a 42 kDa polypeptide possessing transit peptide consisting of 70 amino acid residues. The OsGPT gene maps on chromosome 8 of rice and is linked to the quantitative trait locus for 1000-grain weight. The expression of OsGPT is mainly restricted to heterotrophic tissues. These results suggest that glucose 6-phosphate imported via GPT can be used for starch biosynthesis in rice nongreen plastids.     

Characterization of enhancer trap and gene trap harboring Ac/Ds transposon in transgenic rice

INTRODUCTIONAfterthewholericegenomewassequencedsuccessfully,moreandmoregenescanbepredictedwithdifferentsoftwaresandannotationsystem.However,thefunctionsofpredictedgeneshavetobefurtheridentifiedbybiologicalanalysis.Oneofthemostpowerfulmethodsassigningfunctiontogeneisthroughinsertionmutagenesiswithtrans-posableelementasDNAsequencetag.Ac/Dstrans-posonsystemhasbecomeaverypopulartoolforgenetaggingandfunctionalgenomicsinvariousplantspecies(Altmannetal.,1995;Chinetal.,1999;Enokietal.,1999;Gre…