家蚕地方品种线粒体基因组A+T丰富区的序列及分子进化分析

为了研究家蚕线粒体基因组A+T丰富区的结构和家蚕品种的进化,用PCR方法扩增了12个家蚕(Bombyxmori)地方品种线粒体基因组A+T丰富区及其侧翼序列,分离纯化后克隆到pMD18-T载体进行测序。序列分析表明,克隆片段长度约1.1 kb,基因排列顺序与C108线粒体相同,依次为12S rRNA基因3′端、A+T丰富区、tRNAMet、tRNAIle、tRNAGln和ND2基因5′端,在tRNAGln和ND2基因之间有47 bp的非编码区。以日本野桑蚕(Bombyxmandarina)为外群,用Phylip软件包构建了基于12个家蚕品种线粒体基因组A+T丰富区序列的NJ进化树。结果显示,甘肃种单独聚为一群,其进化早于其它11个品种聚成的类群,说明甘肃种是供试家蚕品种中进化最早的品种。这一结果在分子水平上为黄河流域是家蚕品种的发祥地之一提供了证据,也进一步支持了家蚕品种的中国起源说。对A+T丰富区及其侧翼基因的结构分析表明,家蚕线粒体12S rRNA和ND2基因都十分保守,14个品种统计只分别发生1个和2个碱基转换;A+T丰富区中(A+T)比例高达94.9%以上,第27 nt开始有1个T-串结构,长度为16~19 bp不等;同时还根据3个tRNA基因的核苷酸序列推定了其二级结构。     

Genotypic diversity and migration of clonal lineages of Botrytis cinerea from chickpea fields of Bangladesh inferred by microsatellite markers

An analysis of allelic diversity at nine microsatellite loci provided an insight into the population structure of Botrytis cinerea from four fields (sampled in 2003 and 2004) that represented important regional locations for chickpea production in Bangladesh. Although three populations were limited by sample size after clone‐correction, a total of 51 alleles were amplified among 146 B. cinerea isolates from Bangladesh, which revealed a high amount of within‐population and overall genetic diversity (H_S = 0·48 and H_T = 0·54, respectively). The percentage of maximal genotypic diversity (G) ranged between populations (G = 23–40), with a total of 69 haplotypes detected (G = 25). Bayesian cluster analysis depicted two major clusters distributed among the four Bangladesh populations, indicating population admixture from two origins that have spread throughout these regions. Genotype flow between regions was detected and indicated the spread of clonal lineages, consistent with relatively low differentiation among the four populations (mean G_ST = 0·1, P < 0·05). These results highlighted the potential threat of host resistance breakdown as a result of considerable genetic diversity, genotype flow and the evolutionary potential of B. cinerea.     

Genetic analysis of resistance in barley to barley yellow dwarf virus

The inheritance of resistance to barley yellow dwarf virus (BYDV) was studied in the selected 24 spring and winter barley cultivars that showed a high or intermediate resistance level in 1994‐97 field infection tests. The polymerase chain reaction diagnostic markers YLM and Ylp were used to identify the resistance gene Yd2. The presence of the Yd2 gene was detected with both markers in all the resistant spring barley cultivars and lines from the CIMMYT/ICARDA BYDV nurseries. The results of field tests and genetic analyses in winter barley corresponded with marker analyses only when the Ylp marker was used. Genes non‐allelic with Yd2 were detected by genetic analyses and the Ylp marker in moderately resistant spring barley cultivars ‘Malvaz’, ‘Atribut’ and ‘Madras’, and in the winter barley cultivars ‘Perry’ and ‘Sigra’. Significant levels of resistance to BYDV were obtained by combining the resistance gene Yd2 with genes detected in moderately resistant cultivars. The utilization of analysed resistance sources in barley breeding is discussed.     

Identification of molecular markers associated with sugar-related traits in a <Emphasis Type="Italic">Saccharum</Emphasis> interspecific cross

The cultivated sugarcane (Saccharum spp. hybrids, 2n = 100–130) is one crop for which interspecific hybridization involving wild germplasm has provided a major breakthrough in its improvement. Few clones were used in the initial hybridization event leading to a narrow genetic base for continued cultivar development. Molecular breeding would facilitate the identification and introgression of novel alleles/genes from the wild germplasm into cultivated sugarcane. We report the identification of molecular markers associated with sugar-related traits using an F₁ population derived from a cross between S. officinarum ‘Louisiana Striped’ × S. spontaneum ‘SES 147B’, the two major progenitor species of cultivated sugarcane. Genetic linkage maps of the S. officinarum and S. spontaneum parents were produced using the AFLP, SRAP and TRAP molecular marker techniques. The mapping population was evaluated for sugar-related traits namely, Brix (B) and pol (P) at the early (E) and late (L) plant growing season in the plant cane (04) and first ratoon (05) crops (04EB, 04LB, 04LP, 05EB and 05EP). For S. officinarum, combined across all the traits, a total of 30 putative QTLs was observed with LOD scores ranging from 2.51 to 7.48. The phenotypic variation (adj. R²) explained by all QTLs per trait ranged from 22.1% (04LP) to 48.4% (04EB). For S. spontaneum, a total of 11 putative QTLs was observed with LOD scores ranging from 2.62 to 4.70 and adj. R² ranging from 9.3% (04LP) to 43.0% (04LB). Nine digenic interactions (iQTL) were observed in S. officinarum whereas only three were observed in S. spontaneum. About half of the QTLs contributed by both progenitor species were associated with effects on the trait that was contrary to expectations based on the phenotype of the parent contributing the allele. Quantitative trait loci and their associated effects were consistent across crop-years and growing seasons with very few QTLs being unique to the early season. When the data were reanalyzed using the non-parametric discriminant analysis (DA) approach, significant marker-trait associations were detected for markers that were either identical to or in the vicinity of markers previously identified using the traditional QTL approach. Discriminant analysis also pointed to previously unidentified markers some of which remained unlinked on the map. These preliminary results suggest that DA could be used as a complementary approach to traditional QTL analysis in a crop like sugarcane for which saturated linkage maps are unavailable or difficult to obtain.     

Molecular mapping of a dominant genic male sterility gene Ms in rapeseed (Brassica napus)

Rs1046AB is a genic male sterile two‐type line in rapeseed that has great potential for hybrid seed production. The sterility of this line is conditioned by the interaction of two genes, i.e. the dominant genic male sterility gene (Ms) and the suppressor gene (Rf). The present study was undertaken to identify DNA markers for the Ms locus in a BC₁ population developed from a cross between a male‐sterile plant in Rs1046AB and the fertile canola‐type cultivar ‘Samourai’. Bulked segregant analysis was performed using the amplified fragment length polymorphism (AFLP) methodology. From the survey of 480 AFLP primer combinations, five AFLP markers (P10M13₃₅₀, P13M8₄₀₀, P6M6₄₁₀, E7M1₂₃₀ and E3M15₁₀₀) tightly linked to the target gene were identified. Two of them, E3M15₁₀₀ and P6M6₄₁₀, located the closest, at either side of Ms at a distance of 3.7 and 5.9 cM, respectively. The Ms locus was subsequently mapped on linkage group LG10 in the map developed in this laboratory, adding two additional markers weakly linked to it. This suite of markers will be valuable in designing a marker‐assisted genic male sterility three‐line breeding programme.     

紫苏SNP分子标记开发及遗传多样性分析

紫苏(Perillofrutescens(L.))是一种药食兼用型的植物,具有丰富的营养价值和药用价值,本研究利用特异性位点扩增片段测序技术(specific-locus amplified fragment sequencing,SLAF-seq)对30份紫苏种质资源进行了分子标记开发,以'日本晴'(水稻)为对照,测...     

甘蓝型油菜GZ522早花性状形成的分子基础

选择适当早花早熟的油菜资源是解决多熟制生产中冬季作物油菜与其它夏季作物接茬矛盾的关键;早花是早熟的基础,对油菜早花材料的早花形成原因开展研究,有利于通过分子育种加速选育适合生产需要的新品种.本研究选取稳定的早花早熟品系GZ522作为研究对象,以甘蓝型油菜XY15为对照,采用生物统计学和分子生物学方法对其农艺性状和早花形...     

抗虫转基因植物鉴定方法的研究进展

农作物受害虫侵害严重,给农业生产带来巨大损失,喷施化学杀虫剂使害虫产生抗药性,且污染环境。近年来,转基因技术研究不断深入,抗虫转化研究工作进展迅速。鉴定转基因植物的方法技术有很多种,在此主要阐述了利用标记基因进行鉴定,分子标记,免役技术三大类方法,并对其原理分别进行了简单介绍。     

Molecular tagging of Asiatic soybean rust resistance in exotic genotype EC 241780 reveals complementation of two genes

Asian soybean rust (ASR) caused by Phakopsora pachyrhizi severely reduces seed yield in soybean. Molecular tagging of ASR resistance can help in the process of resistance breeding. In this study, an F₂ population of cross (susceptible cultivar ‘NRC 7’ × resistant exotic genotype EC 241780) was used for bulked segregant analysis (BSA) with 25 SSR (simple sequence repeat) primers linked with six Rpp genes. Among them, five polymorphic SSR markers, viz., Sct 187, SSR 1859, Satt 191 (Rpp1b like loci) and Satt 215, Sat_361 (Rpp2 loci) distinguished the ASR resistant and susceptible bulks and individuals. In combined marker analysis, the markers Satt 191 (Rpp1b like loci) and Satt 215 (Rpp2 loci) were linked with ASR severity score and were also confirmed in individual 110 F₂ segregants. Hence, these markers could be utilized in the marker assisted rust resistance breeding of Rpp1b like and Rpp2 genes. In silico candidate gene analysis for hypersensitive response revealed that Satt 191 linked region was rich in genes encoding apoptotic ATPase having leucine‐rich repeat (LRR) domain.     

Genetic analysis of a CSR10 (indica) × Taraori Basmati F3 population segregating for salt tolerance using ISSR markers

Segregation for salinity tolerance and ISSR markers based molecular polymorphism were investigated in a F₃ plant population raised via single-seed descent method from a cross between salt-tolerant indica rice variety CSR10 and salt-susceptible premium traditional Basmati rice variety Taraori Basmati HBC19. A total of 130 F₃plants were evaluated individually for salinity tolerance on 1–9 scale on the basis of seedling growth parameters; the average score ranged between 1.7 to 8.3. Frequency distribution curve obtained using the salinity tolerance data of F₃ population and a chi-square analysis, showed a good fit to a normal distribution. Eleven plants each in the category of salt-tolerant and salt-susceptible were selected from the segregating F₃ population for ISSR marker analysis. A total of 149 bands (4–11 bands per primer) ranging from 200 to 3530 bp were scored for the two rice varieties and the selected CSR10 × HBC19 segregating F₃ plants using 26 ISSR primers. Of these, 89 were monomorphic and 60 were polymorphic. Of the 60 polymorphic bands,36 and 20 bands were specific to CSR10 andHBC19 respectively. The remaining four bands were amplified using UBC primers 810,848, 853 and 886 and present in only some of the CSR10 × HBC19 F₃ plants. Notably, ISSR primers with dinucleotide repeat motif and 5'-anchored end amplified more number of bands (7.0 bands/primer) compared to3'-anchored dinucleotide primers (5.4bands/primer), but 3'-anchored dinucleotide primers revealed higher level of polymorphism (2.6 polymorphic bands/primer) compared to 5'-anchoreddinucleotide primers (1.43 polymorphic bands/ primer). While distribution of majority of the polymorphic bands were more or less in the expected ratios in salt-tolerant and/or salt-sensitive F₃segregating plants, but some of the bands amplified using UBC ISSR primers 823, 825,826, 849, 853, 864, 866 and 884 showed highly skewed distribution. Such polymorphic bands stand greater chances of having a linkage with the genes/ QTLs for salinity tolerance and shall be the target for further studies. This revised version was published online in July 2006 with corrections to the Cover Date.