Isolation and identification of the three rice monotelosomics

In order to obtain rice monotelosomic, the progeny of 24 telotrisomics, derived from an indica rice variety, Zhongxian 3037, were screened. The variants that differed morphologically from the diploids and the original primary trisomics as well as the telotrisomics were collected for cytological identification. The variants with 24 chromosomes were selected according to the prometaphase chromosomes. From these variants, three monotelosomies with one chromosome arm deletion in each were verified by fluorescence in situ hybridization （FISH） using a rice centromeric BAC clone of 17p22 as a marker probe. The three monotelosomics were derived from telotrisomic 1S, 4L and 11L, respectively. Further identification was conducted on the prometaphase or pachytene chromosomes of the three variants, which were probed with the same centromeric BAC clone together with the corresponding chromosome arm specific makers, a0059H02 （on the short arm of chromosome 1）, a0034E24 （on the long arm of chromosome 4）, and a0071H11 （on the long arm of chromosome 11）. The results indicated that the telocentric chromosomes in the three monotelosom. ics were derived from their respective corresponding telotrisomics. According to the telocentric chromosomes of the variants, they were monotelosomic 1S （one long arm of chromosome 1 was lost）, monotelosomic 4L （one short arm of chromosome 4 was lost） and monotelosomic 11L （one short arm of chromosome 11 was lost）, respectively.     

Centromere inactivation in a dicentric rice chromosome during sexual reproduction

T0135 is a variant selected from the progeny of a rice line telotrisomic for the short arm of chromosome 11 （2n＋IIS＇）. Fluores- cent in situ hybridization （FISH） results indicated that T0135 contained two telocentric chromosomes, which have two centro- mere-specific molecular markers （5S rDNA） for chromosome 11; thus T0135 is a newly-described rice chromosome variant with two dicentric chromosomes, named 22＋11L-＋11L＇＋I IS.11S-＋I 1S-11S. （22 represents the 22 chromosomes excluding chromo- some 11 in the rice genome, ＂-＂ represents the centromere）. To investigate the genetic stability of the rice dicentric chromosomes during sexual reproduction, we observed the chromosome types in the progeny. Ninety-four percent of the progeny had the same chromosome type as the parental line. This result indicates that the dicentric chromosomes are mostly stable during mitosis and meiosis. Immunofluorescence analysis for centromere specific histone H3 （CENH3） revealed that only one centromere is active and the other centromere is inactivated in the rice dicentric chromosomes.     

Mapping of two new brown planthopper resistance genes from wild rice

A brown planthopper (BPH) resistance line, B5, derived its resistance genes from the wild riceOryza officinalis Wall exwatt, was hybridized with Taichung Native 1, a cultivar highly susceptible to BPH. A mapping population composed of randomly selected 167 F₂ individuals was used for determining the BPH resistance genes by the restriction fragment length polymorphism analysis (RFLP). Bulked segregant analysis was conducted to identify RFLP makers linked to the BPH resistance genes in B5. The results indicated that the markers linked to BPH resistance are located at two genomic regions on the long arm of chromosome 3 and the short arm of chromosome 4, respectively. The existence of the two loci was further assessed by the quantitative trait locus (QTL) analysis. We located the two loci at a 3.2 cM interval between G1318 and R1925 on chromosome 3 and a 1.2 cM interval between C820 and S11182 on chromosome 4. Comparison with the BPH genes that have been reported indicated that the BPH resistance genes in B5 are novel. These two genes may be useful BPH resistance resource for rice breeding. Furthermore, the mapping of the two genes is useful for cloning the BPH resistance genes.     

Construction and characterization of a bacterial artificial chromosome library of rice 5460F

Thermo-sensitive genie male sterile (TGMS) rice has a number of desirable characteristics for hybrid rice production. Many studies have demonstrated that the sterility of TGMS rice is controlled by a single recessive gene. It has been mapped for the first time on chromosome 8 and namedtms 1. Several AFLP markers which tightly linked to thetms 1 gene have been identified recently. In order to develop a detailed physical map of thetms1 gene-encompassing region and finally clone thetms1 gene, a bacterial artificial chromosome (BAC) library of rice 5460F (the fertile mutant line of TGMS rice 5460S) using a modified vector pECBAC1 has been constructed. The constructed 5460F BAC library consists of 16 896 clones with an average insert size of 119 kb, which represents about 4.7 times rice haploid genome equivalents. Neither chloroplast nor mitochondrial DNA was detected from the library. The library was screened with three single copy sequence amplified fragment length polymorphism (AFLP) markers which tightly linked totms1 gene as probes and eight positive clones were identified.     

Physical location of the ricePi-5(t), Glh andRTSV genes by ISH of BAC clones

Mapping of low or single-copy sequences on plant chromosomes has proven difficult because of very low frequency of signal detection. Rice BAC library is being used widely in rice genome research due to its distinctive advantages over other library systems. In this study, two biotin-labeled rice BAC clones closely linked to a rice blast resistance, green leafhopper resistance and tungro spherical virus resistance gene,Pi-5(t), Glh, RTSV, werein situ hybridized to rice chromosomes. They were located on the long arm and short arm of chromosome 4 with FL value of 40% and 100% respectively. The frequency of signal detection reached 46.8% and 59.2%. The signal location were consistent with the selective marker on rice saturated molecular map. The results demonstrated the advantages to locate BAC clones to chromosomes byin situ hybridization and will facilitate the rice low or single-copy gene location by using the BAC library. Supported by the National Natural Science Foundation of China and the Doctorate Vesting Point Foundation of the Education Department of the People's Republic of China Yan Huimin: born in 1964, Lecturer     

Spacer length variation in rice 5S rRNA genes revealed by polymerase chain reaction

Polymerase chain reaction (PCR) was used to amplify 5S rRNA spacer from wild rice (Oryza rufipogon and O. nivara) and cultivated rice (indica and japonica varieties of O. sativa L). The results show that there is spacer length variation within and between species, and the typical indica and japonica varieties have their unique banding patterns of amplified 5S rRNA spacers, whereas intermediate showed no specific amplification profile of spacer regions. The 5S rRNA genes in intermediate are either identical with that of indica variety or that of japonica variety. These data suggest that the spacer length polymorphisms can be used to distinguish between closely ralated species and subspecies. Supported by the National Natural Science Foundation of China Yi Qingming, born in Apr. 1938, Professor     

Construction of the primary physical map of rice chromosome 12

A primary physical map of rice chromosome 12 was constructed using marker-based chromosome landing and chromosome walking. A BAC library from IR64 was screened using 84 RFLP markers, 4 STS markers and 6 microsatellite markers on chromosome 12 by colony hybridization and polymerase chain reaction (PCR) amplification. A total of 59 contigs consisting of 419 BAC clones including 5 single-clones were physically aligned on rice chromosome 12 with the largest BAC contig covering 855 kb. The whole physical map had a size of ∼16 Mb and covered about 52% of rice chromosome 12. This physical map will be certainly helpful for map-based gene cloning of agronomically and biological important genes and understanding the genome structure of the chromosome. Foundation item: Supported by Rockefeller Foundation Biography: FU Bin-Ying (1965-), male, Ph. D. candidate, Reseach direction: plant molecular genetics.     

水稻光温敏雄性不育基因连锁标记的分离与鉴定

两系法杂交稻是一种利用水稻杂种优势的重要途径，主要依据水稻光温敏雄性不育系在不同条件下的育性转换用于配制杂交种．以培矮64S(PTGMS)与明恢63杂种自交的F2代为供试材料，采用随机放大多态性DNA(RAPD)技术分离与培矮64S的PTGMS基因连锁的分子标记．在F2代2个分别代表可育和不育的群体以及亲本株系中，采用100个RAPD引物扩放基因组DNA筛选多态性DNA片段．RAPD引物S8产生的DNA片段中，除重复顺序外，有一个长度为0．85kb片段为单拷贝．分子杂交表明，这一单拷贝标记与培矮64S的PTGMS基因连锁．     

Construction of a BAC library from cucumber (Cucumis sativus L.) and identification of linkage group specific clones

A bacterial artificial chromosome (BAC) library consisting of 19,200 clones with an average insert size of 105 kb has been constructed from a cucumber (Cucumis sativus L.) inbred line S94; derived from a cultivar in North China. The entire library was equivalent to approximately 5 haploid cucumber genomes. To facilitate chromosome engineering and anchor the cucumber genetic linkage map to its chromosomes, 15 sequence-characterized amplified regions (SCAR) and seven simple sequence repeats (SSR) markers from each linkage group of cucumber were used to screen an ordered array of pooled BAC DNA with polymerase chain reaction (PCR). Fifteen markers gave at least two positive clones. As a result, 32 BAC clones representing 7 linkage groups of cucumber were identified, which further validated the genome coverage and utility of the library. This BAC library and linkage group specific clones provide essential resources for future research of the cucumber genome.     

Construction of a BAC library from cucumber (Cucumis sativus L.) and identification of linkage group specific clones

A bacterial artificial chromosome (BAC) library consisting of 19,200 clones with an average insert size of 105 kb has been constructed from a cucumber (Cucumis sativus L.) inbred line S94; derived from a cultivar in North China. The entire library was equivalent to approximately 5 haploid cucumber genomes. To facilitate chromosome engineering and anchor the cucumber genetic linkage map to its chromosomes, 15 sequence-characterized amplified regions (SCAR) and seven simple sequence repeats (SSR) markers from each linkage group of cucumber were used to screen an ordered array of pooled BAC DNA with polymerase chain reaction (PCR). Fifteen markers gave at least two positive clones. As a result, 32 BAC clones representing 7 linkage groups of cucumber were identified, which further validated the genome coverage and utility of the library. This BAC library and linkage group specific clones provide essential resources for future research of the cucumber genome.     

Comparative physical mapping of rice BAC clones linked to resistance genes Glh,Bph-3 and xa-5 in Oryza sativa L. and O. granulata Nees et Arn. ex Watt.

Oryza granulata Nees et Arn. ex Watt. is one of the three wild relatives of rice,which are the most valuable for study and utilization in China.In this study,the homology and physical locations of three rice resistance genes,Glh,Bph-3 and xa-5 are comparatively analyzed between O.sativa and O. granulata by Southern blotting and fluorescence in situ hybridization (FISH).The results of Southern blotting indicate that there exist homologous sequences of the tested RFLP markers in O. granulata.By using three bacterial artificial chromosome (BAC) clones scanned by the tested RFLP as probes, FISH signals are detected on both mitotic and pachytene chromosomes in O.sativa and O.granulata.Dual-color FISH demonstrates that two of the three BAC clones (14E16 and 38J9) are located on the short arm of the same chromosome pair in O. granulata. Additionally, colinearity is shown for the two clones between O.sativa and O.granulata. Another BAC clone 44B4 is located on the end of the short arm of other chromosome pair in these two species.Although the phylogenetic relationship between O.sativa and O.granulata is the most distinct in Oryza and these two species have evidently different biological features and ecological habits, the relative lengths and arm ratios of the detected chromosomes and the relative positions of the tested clone signals on chromosomes in O. granulata are quite similar to those in O. sativa.     

Knob-associated tandem repeats on mitotic chromosomes in maize,Zea diploperennis and their hybrids

Knob-associated tandem repeats, 180-bp repeats and TR-1 elements, together with 45S rDNA were located on mitotic chromosomes of Zea diploperennis (DP),maize inbred line F102 and their hybrid. In DP, knobs on the short arm of chromosomes 1 and 4 and on the long arm ofthe chromosomes 4 and 5 are composed predominantly of the 180-bp repeats. In addition, 180-bp repeats existed together with TR-1 elements were also detected on the short arm ofchromosomes 2 and 5 and on the long arm of the chromosomes 2, 6, 7, 8 and 9. In maize inbred line F102, 180-bp repeats were present in chromosomes 7S and one homologue of chromosomes 8L. TR-1 elements appeared on satellite of chromosome 6 and no detectable hybridization site co-located with 180-bp repeats was observed in maize F102.Polymorphism of size, number, and distribution of 180-bp and TR-1 signals were revealed among different chromosomes in these two species and heteromorphism existed between some homologous chromosomes in the same species.Using these excellent landmarks, the interspecific hybrid of maize and DP were identified. The results suggest that comparative analysis of 180-bp repeats and TR-1 elements may help understand the genome organization and the evolution in Zea.     

Construction of a BAC library from cucumber （Cucumis sativus L.） and identification of linkage group specific clones

A bacterial artificial chromosome （BAC） library consisting of 19,200 clones with an average insert size of 105 kb has been constructed from a cucumber （Cucumis sativus L.） inbred line S94, derived from a cultivar in North China. The entire library was equivalent to approximately 5 haploid cucumber genomes. To facilitate chromosome engineering and anchor the cucumber genetic linkage map to its chromosomes, 15 sequence-characterized amplified regions （SCAR） and seven simple sequence repeats （SSR） markers from each linkage group of cucumber were used to screen an ordered array of pooled BAC DNA with polymerase chain reaction （PCR）. Fifteen markers gave at least two positive clones. As a result, 22 BAC clones representing 7 linkage groups of cucumber were identified, which further validated the genome coverage and utility of the library. This BAC library and linkage group specific clones provide essential resources for future research of the cucumber genome.     

竹叶蛙(Rana Versabilis)核型的研究

采用骨髓细胞直接制备染色体标本法,研究了产于福建的竹叶蛙(Rana Versabilis)核型,其二倍体细胞的染色体数为26条(2n=26),由五对大型染色体和八对小型染色体组成,全部染色体均为中部和亚中部着丝粒染色体,这是典型的蛙属核型式。但其一恒定而清晰的次缢痕是在第6对染色体的短臂上。未见异型性染色体。     

利用小麦5B效应引入外源基因的研究（Ⅰ）易位系的培育

ｄｕｒｕｍ小麦的代换系ｄｉ－ｓｕｂ５Ｄ（５Ｂ）与添加系ｄｉ－ａｄｄｅ４ｔｓ杂交，再用ｄｉ－ｓｕｂ５Ｄ（５Ｂ）进行回交，在自交后代中选育出了易位系１０３２。该易位系染色体数２ｎ＝２８，表现型为非蜡质。这一结果证明了在ｄｕｒｕｍ小麦中也可以利用５Ｂ染色体效应，通过诱发部份同源染色体间的配对，获得易位体。     

水稻苯达松敏感致死基因的RAPD标记的克隆及测序

用3S Spin DNA Agarose Gel Purification Kit试剂盒将与水稻苯达松敏感致死基因相连锁的RAPD遗传标记S20—420和S316—600回收纯化，连接于pGEM—T载体并克隆测序，得到了S20—420和S316—600的全序列，其长度分别为423bp、606bp．将两端序列设计特异PCR扩增引物可用于检测水稻苯达松敏感致死基因和标记辅助育种．     

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…     

Evidence against linkage of schizophrenia to markers on chromosome 5 in a northern Swedish pedigree

Schizophrenia is a severe mental illness with a typically chronic course affecting nearly 1% of the human population. It is generally accepted that genetic factors have an important pathogenic role in a substantial portion of schizophrenia cases; however, despite decades of family studies, there is no agreed-upon mode of inheritance. The discovery of genetic aetiologic factors and resolution of the inheritance pattern(s) will undoubtably emerge from genetic linkage studies. With these objectives in mind, we undertook a linkage project, starting in 1985, in a previously well-documented kindred from north Sweden. Multipoint linkage analyses were used to screen the proximal long arm of chromosome 5 using restriction fragment length polymorphism (RFLP) markers at five loci and the distal long arm using RFLPs at two loci, one of which was the locus for the glucocorticoid receptor. We found strong evidence against linkage between schizophrenia and the seven loci. These results, together with the positive evidence for linkage of schizophrenia with markers in the proximal long arm of chromosome 5 lead us to conclude that the genetic factors underlying schizophrenia are heterogeneous.     

Genetic analysis and fine mapping of a lax mutant in rice

We have analyzed a lax mutant that exhibits altered panicle architecture in rice.The primary and secondary rachis-branches are normally initiated and each branch ends in a terminal spikelet,but all the lateral spikelets are absent and the terminal spikelet displays variegated structures in the mutant.An F2 population from the cross between the lax mutant and a japonica variety,W11,was constructed and analyzed.Using microsatellite and CAPS markers,the lax locus was mapped on the long arm of chromosome 1,co-segregated with a CAPS marker,LZ1,within an interval of 0.28 cM between a CAPS marker,HB2,and a microsatellite marker,MRG4389.RT-PCR analysis revealed that the expressions of the rice B-function MADS-box genes OsMADS2,OsMADS4,OsMADS16 and OsMADS3 were significantly reduced,whereas the expression of the rice A-function gene RAPIA was not altered.     

Chromosome G-banding in situ hybridization of RFLP marker umc58 linked with the gene hm1 dictatingHelminthosporium carbonum susceptibility1 in maize

The technique of simultaneous G-banding and in situ hybridization has been developed in plants for the first time. Using this technique, RFLP marker umc58 closely linked with the hm1 gene dictatingHelminthosporium carbonum susceptibility1 was localized onto 1L3 (chromosome 1, long arm, the third band from the centromere to the end of the arm), 5L5 and 9L5. The results demonstrated that umc58 was a triplicated sequence. It was deduced that umc58 probably was in a duplicated region that includes a part ofHelminthosporium carbonum susceptibility genes (hm1 and hm2), as the hybridization sites of umc58 in chromosomes 1 and 9 were those at which the genes localize. The techniques of simultaneous G-banding and ISH in plants are discussed.