耐大豆疫霉根腐病QTL定位的研究

利用1200个RAPD随机引物和341对SSR引物对Conrad×OX760的重组自交系(RIL)F2:6群体的耐大豆疫霉根腐病基因进行QTL定位。试验设两个地点、两个年限,在MLG D1b+W和MLG M连锁群上检测到3个QTL,即QP-1(OPL18-800bp)、QP-2(OPN03-600bp)和QP-3(Satt536和Satt463)。每个QTL对病害损失率的贡献率从13.34%到22.31%不等。QP-1和QP-2经多重QTL分析(Mapmaker/QTL1.1)对两年(2000年和2001年)两点(Wood-slee和Werver)平均病害损失率的贡献率合计达44.5%,QP-3对2001年Woodslee试验点的病害损失率的贡献率为15.2%,QP-1对2000年Woodslee试验点的病害损失率的贡献率为21.55%,对2000年Wever试验点的病害损失率的贡献率16.71%,及对两年两点平均病害损失率的贡献率为22.31%。在大多数生态环境下能稳定的、再次被检测出的QTL,可以作为育种工作中的重点选择指标,用以指导耐大豆疫霉根腐病品种的分子辅助选育。     

Molecular basis of the low linolenic acid trait in soybean EMS mutant line RG10

A possible solution to stability problems is to genetically reduce the content of linolenic acid in soybean seed. RG10 is a low linolenic acid line (<25 g/kg) produced by ethyl methane sulfonate (EMS) treatment of the low linolenic acid EMS mutant line C1640. The objective of this study was to determine the molecular basis of the low linolenic acid trait in RG10. Sequence analyses of mutant RG10 and wild-type OX948 ω-fatty acid desaturase ( Fad3 ) genes showed that the low level of linolenic acid in RG10 is likely a result of mutations in two Fad3 genes. A mutation in the Fad3A gene introduces a stop codon in exon 6 that would prematurely terminate translation and a second mutation in the 5' splice site of intron 5 of the Fad3B gene may result in abnormal mRNA splicing products. Both mutations would result in a non-functional enzyme. Molecular markers developed for these mutations should simplify and accelerate introgression of the RG10-based low linolenic acid trait into elite soybean cultivars.     

Protein recovery in soymilk and various soluble fractions as a function of genotype differences, changes during heating, and homogenization

Harovinton, a variety of tofu type soybean, and 11 derived null soybean genotypes lacking specific glycinin (11S) and beta-conglycinin (7S) protein subunits were investigated to determine whether changes in protein composition affected the protein recovery in soymilk and its soluble fractions after various centrifugation steps. As both heating and homogenization have a marked effect on the increase in protein solubility, the changes occurring during these processing steps were studied for each soybean genotype. Harovinton and 11S-null genotypes showed significantly higher protein yields than the other genotypes evaluated. Subunits of group I (A(1), A(2)) of glycinin had a negative impact on protein solubility in all treatments, but this effect was the greatest in unheated soymilk samples. Samples containing a high beta-conglycinin to glycinin ratio showed an effect of heating on the solubility of the protein, as beta-conglycinin subunits aggregate with heating. The presence of the alpha' subunit of beta-conglycinin aids in the recovery of protein in the supernatant prepared from lines containing group I (A(1,4) A(2)) glycinin. The results of this study will help determine which specific protein composition will confer an increased stability in soymilk and soymilk-derived products.     

Marker-assisted selection of common beans for resistance to common bacterial blight: efficacy and economics

The possibility of using random amplified polymorphic DNA (RAPD) markers previously mapped in the common bean PC50/XANI59 population to select for resistance to common bacterial blight (CBB) in different populations was examined. Two out of 02 selected RAPD markers were polymorphic in HR56 and W0633d, the parental lines used in this experiment. Cosegregation analysis of the two polymorphic markers and disease reaction in a recombinant inbred (RI) population derived from HR67/W1744d confirmed that one of the two RAPD markers, BC420₉₀₀, was significantly associated with a major quantitative trait locus‐conditioning resistance to CBB in HR67. This locus accounted for approximately 51) of the phenotypic variation. The RAPD marker was transformed into a sequence characterized amplified region (SCAR) marker and used for selection in a different population derived from ‘Envoy’/HR67. Prediction for resistance to CBB with the BC420_.990 SCAR marker was 94.2% accurate in this population. A comparison between marker‐assisted selection (MAS) and conventional greenhouse screening showed that the cost of MAS is about one‐third less than that of the greenhouse test.     

Co-operative fisheries management of the cross border Lake Peipsi-Pihkva

This paper focuses on the management and socio-economic principles for allocation of the commercial fish resources of Lake Peipsi-Pihkva. The fish resources of this cross border lake are very important both for Russia and Estonia. Recent changes in the Estonian and Russian economies, and the appearance of the state border dividing the lake, have resulted in deep changes in economic, social and legal issues related to the fishery. As the lake is now an international waterbody, the Intergovernmental Estonian–Russian Fishery Commission (ERFC) agreed for co-operative management measures annually from 1994. The ERFC is responsible for all general decisions on management strategies and technical measures used in fishery management. The stocks of most commercial fish species in Lake Peipsi-Pihkva are still abundant, and the economic status of the fishermen is relatively good. It may be concluded that co-operative management of the Lake Peipsi-Pihkva fisheries have been successful.     

Mapping QTL tolerance to <Emphasis Type="Italic">Phytophthora</Emphasis> root rot in soybean using microsatellite and RAPD/SCAR derived markers

Broad tolerance to phytophthora root rot (PRR) caused by Phytophthora sojae has become an important goal for the improvement of soybean (Glycine max) because of the rapid spread of races that defeat the available resistance genes. The aim of this research was to identify the location of quantitative trait loci (QTL) in ‘Conrad’, a soybean cultivar with broad tolerance to many races of P. sojae. A PRR susceptible breeding line ‘OX760-6-1’was crossed with Conrad. Through single-seed-descent, 112, F₂ derived, F₇ recombinant inbred lines (RILs) were advanced. A total of 39 random amplified polymorphic DNA bands (RAPDs) and 89 type 1 microsatellite (simple sequence repeat; SSR) markers were used to construct a genetic linkage map. In the greenhouse, RILs were inoculated with four P. sojae isolates (three from China and one from Canada). Disease was measured as the percent of dead plants 20 days after germination in P. sojae inoculated vermiculite in the greenhouse. Three QTLs (QGP1, QGP2, QGP3) for PRR tolerance in the greenhouse were detected using WinQTLCart 2.0 with a log-likelihood (LOD) score 27.14 acquired through permutations (1,000 at P ≤ 0.05). QGP1 (near Satt509) was located at linkage group F and explained 13.2%, 5.9%, and 6.7% of the phenotypic variance for tolerance to the JiXi, JianSanJiang and ShuangYaShan isolates, respectively. QGP2 (near Satt334) was located in a different interval on linkage group F and explained 5.1% and 2.4% of the phenotypic variance for JiXi and ShuangYaShan isolates, respectively. QGP3 was located on linkage group D1b + W (near OPL18₈₀₀/SCL18₆₅₉) and explained 10.2% of the phenotypic variance for Woodslee isolate. QGP1 and QGP2 appeared to be associated with PRR tolerance across a range of isolates but QGP3 was active only against the Woodslee isolate. At Woodslee and Weaver (in Ontario) in 2000, the interval associated with QGP3 explained 21.6% and 16.7% of phenotypic variance in resistance to PRR, respectively and was referred as QFP1. The identified QTLs would be beneficial for marker assistant selection of PRR tolerance varieties against both China and North America P. sojae races. Yingpeng Han and Weili Teng have equal contribution to the paper.     

A quantitative trait locus influencing tolerance to Phytophthora root rot in the soybean cultivar ‘Conrad’

‘Conrad’, a soybean cultivar tolerant to Phytophthora root rot (PRR), and ‘OX760-6-1’, a breeding line with low tolerance to PRR, were crossed. F₂ derived recombinant inbred lines were advanced to F₆ to generate a population through single-seed descent. This population was used to identify quantitative trait loci (QTLs) influencing PRR tolerance in ‘Conrad’. A total of 99 simple sequence repeat (SSR), or microsatellite, markers that were polymorphic and clearly segregated in the F₆ mapping population were used for QTL detection. Based on the data of PRR in the field at two planting locations, Woodslee and Weaver, for the years 2000 and 2001, one putative QTL, designated as Qsatt414-596, was detected using MapMaker/QTL. Qsatt414-596 was flanked by two SSR markers from the linkage group MLG J, Satt414 and Satt596. Satt414 and Satt596 were also detected to be significantly (P < 0.005) associated with PRR using the SAS GLM procedure and were estimated to explain 13.7% and 21.5% of the total phenotypic variance, respectively.     

Soyasapogenol A and B distribution in soybean (Glycine max L. Merr.) in relation to seed physiology, genetic variability, and growing location

An efficient analytical method utilizing high-performance liquid chromatography (HPLC)/evaporative light scattering detector (ELSD) was developed to isolate and quantify the two major soyasaponin aglycones or precursors in soybeans, triterpene soyasapogenol A and B. Soaking of seeds in water up to 15 h did not change the content of soyasapogenols. Seed germination had no influence on soyasapogenol A content but increased the accumulation of soyasapogenol B. Soyasapogenols were mainly concentrated in the axis of the seeds as compared with the cotyledons and seed coat. In the seedling, the root (radicle) contained the highest concentration of soyasapogenol A, while the plumule had the greatest amounts of soyasapogenol B. In 10 advanced food-grade soybean cultivars grown in four locations in Ontario, total soyasapogenol content in soybeans was 2 +/- 0.3 mg/g. Soyasapogenol B content (1.5 +/- 0.27 mg/g) was 2.5-4.5-fold higher than soyasapogenol A content (0.49 +/- 0.1 mg/g). A significant variation in soyasapogenol content was observed among cultivars and growing locations. There was no significant correlation between the content of soyasapogenols and the total isoflavone aglycones.     

An SSR marker in the nitrate reductase gene of common bean is tightly linked to a major gene conferring resistance to common bacterial blight

A simple sequence repeat (SSR) marker composed of a tetra nucleotide repeat is tightly linked to a major gene of common bean (Phaseolus vulgaris L.) conferring resistance to common bacterial blight (CBB) incited by Xanthomonas axonopodis pv. phasoli (Xap). This SSR is located in the third intron region of the common bean nitrate reductase (NR) gene, which is mapped to linkage group (LG) H7, corresponding to LG B7 of the bean Core map. Co-segregation analysis between the SSR marker and CBB resistance in a recombinant inbred line (RIL) population demonstrated a tight linkage between the NR gene-specific marker and the major gene for CBB resistance. In total, the marker explained approximately 70% of the phenotypic variation in the population. Because it is co-dominant, this SSR marker should be more efficient for marker-assisted selection (MAS) than dominant/recessive random amplified polymorphic DNA (RAPD) or sequence characterized amplified region (SCAR) markers that have been developed, especially for early generation selection. This revised version was published online in August 2006 with corrections to the Cover Date.