绿豆种子休眠性和百粒重的QTLs和互作分析

利用绿豆Berken/ACC41重组自交系在北京种植得到的121个F10家系和79个RFLP分子标记,采用改进复合区间作图法对绿豆种子休眠性和百粒重进行数量性状基因定位及上位性互作分析.检测到与发芽势有关的QTL 3个,与发芽率有关的QTL 4个,分别位于第1、11连锁群,解释表型变异的8.17%～12.14%和4.34%～12.69%.检测到与百粒重有关的QTL 5个,分别位于第2、8、9、11连锁群,解释表型变异的4.58%～10.36%.增加发芽率和百粒重的基因效应均来自母本Berken.分别检测到发芽势、发芽率和百粒重的加性×加性上位性互作8、9、9对,对这3个性状的总表型贡献率分别达到66.58%、47.91%、39.90%.本文初步分析了休眠性和百粒重的关系,并与前人的研究结果作了比较,旨在通过分子标记辅助选择,培育适度休眠的优良绿豆品种,进而解决绿豆收获前的荚上子粒发芽问题.     

基于同源基因的病原菌鉴定和分型靶位点的功能基因组学研究

利用病原菌序列差异,对病原菌特定基因和位点进行检测,可以快速发现和鉴别病原菌的分类和特征,对传染病快速诊断和溯源具有基础性意义和重要价值.本文旨在覆盖中国重要传染病的103种病原菌,寻找各分类阶元中特有的同源基因,并从中挑选出适合用于病原菌鉴定、分型的候选基因.利用生物信息学和基因组学方法,对已有全基因组序列的275株病原菌的836415个基因进行比对分析,进一步明确菌株的门、纲、目、科、属各分类阶元中特有的同源基因集合;通过COG功能分类方法,对同源基因集合进行功能注释,并分析在不同分类阶元内的保守基因功能的变化规律.本研究寻找到适合鉴定和分型的不同分类阶元（门、纲、目、科、属）的同源基因集合共19563个（门2891个、纲1016个、目3601个、科10130个、属1925个）.对同源基因功能的分析表明,适合对病原菌进行鉴定的基因在不同分类阶元中,表现的功能存在较大差异.革兰氏阳性和阴性病原菌在不同分类阶元中,同源基因表现出的功能也存在差异.该结果将为对在中国广泛存在的病原菌进行检测所涉及的探针、芯片设计提供理论依据,加快目标探针的筛选工作.同时,研究也是首次将世界范围内的全基因组数据和中国重大传染病涉及的病原菌紧密联系结合,为利用功能基因组学开展区域性、有针对性的病原检测和监测,提供候选基因和位点筛选的新方法.相关结果在细菌的元基因组学研究中也具有一定的应用价值.     

绿豆和花生的超弱发光

对黄化绿豆幼苗先形态建成过程的超弱发光图象（延迟发光）的初步观察发现：见光培养40min后的绿豆幼苗即可探测到明显的延迟发光;见光时间越长,光诱导的延迟发光强度也越强。从绿豆和花生幼苗的趋弱发光图象来看,生长健壮的幼苗发光较强。其中茎尖和新生幼叶的延迟发光最强,上胚轴、子叶和下胚轴弯钩较强,下胚轴伸长部分次之,根部发光最弱。从不同发育阶段叶片的超弱发光图象来看,光合作用较强、新陈代谢旺盛的成熟叶片的超弱发光较强;光合作用和其它代谢过程相对较弱的叶片（伸展叶、老叶和幼叶）,其超弱发光强度相应较弱。而叶绿素提取液和失活绿叶观测不到超弱发光。此外,对超弱发光光谱的初步研究表明它很可能来自光合作用中叶绿素的发光。这些都暗示,植物的（诱导）超弱发光与光形态建成和光合作用等生长代谢过程密切相关。     

Genetic Analysis and Fine Mapping of Two Genes for Grain Shape and Weight in Rice

To identity genetic loci controlling grain weight, an elite indica rice variety, Baodali, with large grains was Identified and used in this study. Its derived F2, F3 and BC2F2 with another japonica dee variety Zhonghua 11 were used as mapping populations. Unkage analyses demonstrated that two genes controlling grain weight, designated as GW3 and GW6, were mapped to chromosome 3 and chromosome 6, respectively. Fine mapping delimited GW3 to a 122 kb physical distance between two sequence tagged site markers (WGW16 and WGW19) containing 16 open reading frames annotated by The Institute for Ganomic Research (http://www.tigr.org). GW6 was further mapped between two simple sequence repeat markers (RM7179 and RM3187). These results are useful for both marker assisted selection of grain weight, and for further cloning of GW genes, which will contribute to the dissection of the molecular mechanism underlying grain weight in rice.     

Genetic Analysis and Fine Mapping of Two Genes for Grain Shape and Weight in Rice

To identify genetic loci controlling grain weight, an elite indica rice variety, Baodali, with large grains was identified and used in this study. Its derived F2, F3 and BC2 F2 with another japonica rice variety Zhonghua 11 were used as mapping populations. Linkage analyses demonstrated that two genes controlling grain weight, designated as GW3 and GW6, were mapped to chromosome 3 and chromosome 6, respectively. Fine mapping delimited GW3 to a 122 kb physical distance between two sequence tagged site markers （WGWt6 and WGW19） containing 16 open reading frames annotated by The Institute for Genomic Research （http：//www.tigr.org）. GW6 was further mapped between two simple sequence repeat markers （RM7179 and RM3187）. These results are useful for both marker assisted selection of grain weight, and for further cloning of GW genes, which will contribute to the dissection of the molecular mechanism underlying grain weight in rice.     

Occurrence of Southern Bean Mosaic Virus on Cowpea in Senegal

For identification of cowpea viruses existing in Senegal, 180 samples collected from 4 different locations were examined. Initially agar gel diffusion tests were employed to identify the viruses present in these samples using antisera to 3 beetle-transmitted viruses viz. CPMV, SBMV and CMeV. The results indicated the presence of SBMV in 78 samples mostly from Casamance while none of these viruses were detected in the samples collected from northern Senegal. These results were later confirmed by Enzyme-linked Immunosorbent Assay (ELISA). This is the first report of occurrence of SBMV in Senegal.     

Immobilized and Free Apoplastic Pectinmethylesterases in Mung Bean Hypocotyl

The nature and the action pattern of apoplastic pectinmethylesterase (PME) isoforms were investigated in mung bean [Vigna radiata (L.) Wilzeck] hypocotyls. Successive extractions of neutral and alkaline PME isoforms present in hypocotyl native cell walls (referred to as PE1, PE2, PE3, PE4, with increasingly basic isoelectric points) revealed that solubilization of PE1, PE2, and PE4 did not induce any significant decrease in the cell-wall-bound PME activity. The in vitro de-esterification occurring when isolated cell walls were incubated with pectin resulted, then, from the activity of PE3. In addition, pH control of PME activity was shown to be much stronger for enzymes bound to cell walls, in their native state or reintroduced after solubilization, than for enzymes in solution. Mature cell walls showed much more activity than young cell walls, and were relatively enriched in two acidic PME isoforms missing in young cell walls. One acidic PME was also detected in the extracellular fluid. The acidic and neutral isoforms that could be easily transferred from their binding sites to their substrate might be those involved in the demethylation process developing along the mung bean hypocotyl.     

Transcriptome Sequencing of Mung Bean (Vigna radiate L.) Genes and the Identification of EST-SSR Markers

Mung bean (Vigna radiate (L.) Wilczek) is an important traditional food legume crop, with high economic and nutritional value. It is widely grown in China and other Asian countries. Despite its importance, genomic information is currently unavailable for this crop plant species or some of its close relatives in the Vigna genus. In this study, more than 103 million high quality cDNA sequence reads were obtained from mung bean using Illumina paired-end sequencing technology. The processed reads were assembled into 48,693 unigenes with an average length of 874 bp. Of these unigenes, 25,820 (53.0%) and 23,235 (47.7%) showed significant similarity to proteins in the NCBI non-redundant protein and nucleotide sequence databases, respectively. Furthermore, 19,242 (39.5%) could be classified into gene ontology categories, 18,316 (37.6%) into Swiss-Prot categories and 10,918 (22.4%) into KOG database categories (E-value < 1.0E-5). A total of 6,585 (8.3%) were mapped onto 244 pathways using the Kyoto Encyclopedia of Genes and Genome (KEGG) pathway database. Among the unigenes, 10,053 sequences contained a unique simple sequence repeat (SSR), and 2,303 sequences contained more than one SSR together in the same expressed sequence tag (EST). A total of 13,134 EST-SSRs were identified as potential molecular markers, with mono-nucleotide A/T repeats being the most abundant motif class and G/C repeats being rare. In this SSR analysis, we found five main repeat motifs: AG/CT (30.8%), GAA/TTC (12.6%), AAAT/ATTT (6.8%), AAAAT/ATTTT (6.2%) and AAAAAT/ATTTTT (1.9%). A total of 200 SSR loci were randomly selected for validation by PCR amplification as EST-SSR markers. Of these, 66 marker primer pairs produced reproducible amplicons that were polymorphic among 31 mung bean accessions selected from diverse geographical locations. The large number of SSR-containing sequences found in this study will be valuable for the construction of a high-resolution genetic linkage maps, association or comparative mapping and genetic analyses of various Vigna species.     

Rapid Identification of Candidate Genes for Seed Weight Using the SLAF-Seq Method in Brassica napus

Seed weight is a critical and direct trait for oilseed crop seed yield. Understanding its genetic mechanism is of great importance for yield improvement in Brassica napus breeding. Two hundred and fifty doubled haploid lines derived by microspore culture were developed from a cross between a large-seed line G-42 and a small-seed line 7–9. According to the 1000-seed weight (TSW) data, the individual DNA of the heaviest 46 lines and the lightest 47 lines were respectively selected to establish two bulked DNA pools. A new high-throughput sequencing technology, Specific Locus Amplified Fragment Sequencing (SLAF-seq), was used to identify candidate genes of TSW in association analysis combined with bulked segregant analysis (BSA). A total of 1,933 high quality polymorphic SLAF markers were developed and 4 associated markers of TSW were procured. A hot region of ~0.58 Mb at nucleotides 25,401,885–25,985,931 on ChrA09 containing 91 candidate genes was identified as tightly associated with the TSW trait. From annotation information, four genes (GSBRNA2T00037136001, GSBRNA2T00037157001, GSBRNA2T00037129001 and GSBRNA2T00069389001) might be interesting candidate genes that are highly related to seed weight.     

RFLP Mapping of Genes Conferring Complete and Partial Resistance to Blast in a Durably Resistant Rice Cultivar

Moroberekan, a japonica rice cultivar with durable resistance to blast disease in Asia, was crossed to the highly susceptible indica cultivar, CO39, and 281 F(7) recombinant inbred (RI) lines were produced by single seed descent. The population was evaluated for blast resistance in the greenhouse and the field, and was analyzed with 127 restriction fragment length polymorphism (RFLP) markers. Two dominant loci associated with qualitative resistance to five isolates of the fungus were tentatively named Pi-5(t) and Pi-7(t). They were mapped on chromosomes 4 and 11, respectively. To identify quantitative trait loci (QTLs) affecting partial resistance, RI lines were inoculated with isolate PO6-6 of Pyricularia oryzae in polycyclic tests. Ten chromosomal segments were found to be associated with effects on lesion number (P < 0.0001 and LOD > 6.0). Three of the markers associated with QTLs for partial resistance had been reported to be linked to complete blast resistance in previous studies. QTLs identified in greenhouse tests were good predictors of blast resistance at two field sites. This study illustrates the usefulness of RI lines for mapping a complex trait such as blast resistance and suggests that durable resistance in the traditional variety, Moroberekan, involves a complex of genes associated with both partial and complete resistance.     

Effects of Salt Stress on Growth, Nodulation and Nitrogen Fixation in Cowpea and Mung Beans

The effects of salt stress on growth, nodulation, and nitrogen accumulation in cowpea (Vigna sinensis) and mung beans (Vigna aureus) were studied in sand culture. Salinity (NaCl) retarded the growth of leaves, stem and roots of both the crops. Root growth of mung beans was more sensitive to the increase in salt stress than that of cowpea. The relative growth rates of stressed plant parts declined initially but were subsequently higher than those of control for a period, suggesting that the plants tended to adapt to unfavourable environment even while being stressed. The total nodule number, weight and nitrogen content per plant decreased due to salt treatment, which interfered with the initiation of nodules but not with their further development. There was a considerable fall in the nitrogen fixation efficiency of mung beans under saline environment; it was not so in cowpea.     

黄腐酸和汪平酸对小麦种子萌发与幼苗生长及绿豆下胚轴生根的影响

用黄腐酸和汪平酸浸种后,对于小麦种子萌发无明显影响。用不同浓度的黄腐酸和汪平酸溶液培养小麦幼苗,发现适当浓度时对于幼苗及根系生长与分化有促进作用,高浓度则表现为抑制作用。10ppm黄腐酸和50ppm汪平酸可显著增加去根绿豆下胚轴再生根数,而且在一定的浓度范围内,随着浓度的增高,根数不断增加而根长却逐渐减短。     

Evolution of Orthologous Intronless and Intron-Bearing Globin Genes in Two Insect Species

While globin genes ctt-2β and ctt-9.1 in Chironomus thummi thummi each have a single intron, all of the other insect globin genes reported so far are intronless. We analyzed four globin genes linked to the two intron-bearing genes in C. th. thummi. Three have a single intron at the same position as ctt-2β and ctt-9.1; the fourth is intronless and lies between intron bearing genes. Finally, in addition to its intron, one gene (ctt-13RT) was recently interrupted by retrotransposition. Phylogenetic analyses show that the six genes in C. th. thummi share common ancestry with five globin genes in the distantly related species C. tentans, and that a 5-gene ancestral cluster predates the divergence of the two species. One gene in the ancestral cluster gave rise to ctn-ORFB in C. tentans, and duplicated in C. th. thummi to create ctt-11 and ctt-12. From parsimonious calculations of evolutionary distances since speciation, ctt-11, ctt-12, and ctn-ORFB evolved rapidly, while ctn-ORFE in C. tentans evolved slowly compared to other globin genes in the clusters. While these four globins are under selective pressure, we suggest that most chironomid globin genes were not selected for their unique function. Instead, we propose that high gene copy number itself was selected because conditions favored organisms that could synthesize more hemoglobin. High gene copy number selection to produce more of a useful product may be the basis of forming multigene families, all of whose members initially accumulate neutral substitutions while retaining essential function. Maintenance of a large family of globin genes not only ensured high levels of hemoglobin production, but may have facilitated the extensive divergence of chironomids into as many as 5000 species. Received: 31 December 1996 / Accepted: 16 May 1997     

Mapping of RFLP probes characterized for their polymorphism on wheat

 Wheat anonymous probes were selected for their efficiency for providing a readable hybridization pattern and revealing RFLP among wheat varieties. We report the mapping of 132 such probes (20 wheat-leaf cDNA, 28 wheat-root cDNA and 84 genomic DNA) on the reference population of the International Triticeae Mapping Initiative (ITMI) derived from the cross W-7984 with Opata85. Each probe has been characterized for its polymorphism information content. The 132 probes allowed us to map 160 loci. Received: 7 July 1998 / Accepted: 19 October 1998