Use of Random Amplified Polymorphic DNA Markers for Mapping the Chickpea Genome

Three interspecific crosses were developed using Cicer arietinum (ICC 4918) as the female parent and wild Cicer species [C. reticulatum - JM 2100, JM 2106 and C. echinospermum - ICCW 44] as the male parent. Cicer arietinum (ICC 4918) × C. reticulatum (JM 2100) cross produced the largest number of F₂ plants and was chosen for linkage mapping using Random Amplified Polymorphic DNA (RAPD) primers. A partial linkage map was constructed based upon the segregation of 36 RAPD markers obtained by amplification using 35 primers. The linkage map consists of two linkage groups with 17 linked markers covering a total of 464.9 cM. Analyses also revealed association of three morphological traits with linked RAPD markers. Out of seven morphological traits tested for association with linked markers in the segregating plants, four Quantitative trait loci (QTL) were detected for the trait leaf length and three QTLs each for the traits leaf width and erect plant habit.     

复合益生菌对白羽肉鸡肌肉品质的影响及作用机理

【目的】探究饮水中添加复合益生菌制剂(地衣芽孢杆菌、枯草芽孢杆菌和丁酸梭菌)对肉鸡肌肉品质的影响及作用机理。【方法】试验随机选取360只1日龄白羽肉仔鸡,随机分为3个处理组：对照组(CON),正常饮水;低剂量益生菌组(LG),饮水添加0.2%复合益生菌;高剂量益生菌组(HG),饮水添加0.4%复合益生菌,试验为期42d。【结果】与CON组相比,LG组和HG组显著增加肉鸡7、35和42 d平均体重,显著提高HG组肉鸡21-28、28-35、35-42阶段的平均日增重(P<0.05),LG组仅显著提高35-42阶段平均日增重;显著提高胸肌45 min、24 h、48 h红度和24 h黄度,降低24 h和48 h亮度及48 h滴水损失和蒸煮损失。HG组胸肌粗蛋白和粗脂肪含量显著高于CON组,而LG组差异不显著;两组均可降低胸肌灰分含量。添加复合益生菌可显著提高总抗氧化能力(total antioxidant capacity,T-AOC),而总超氧化物歧化酶(total-superoxide dismutase,T-SOD)、过氧化氢酶(catalase,CAT)含量有上升趋势;显著上...     

Evaluation of breeding utility of a chromosomal segment from Lycopersicon chmielewskii that enhances cultivated tomato soluble solids

A chromosomal segment from the wild tomato species, Lycopersicon chmielewskii, when backcrossed into the tomato cultivar VF145B-7879, increases fruit soluble solids concentration. In the investigation reported here, the near-isoline (VF145B-7M) homozygous for the chmielewskii (chm) chromosomal segment was crossed to the cultivar to study allelic interactions and then hybridized to three commercial cultivars (UC204c, E6203, and ChicoIII) to investigate the effect of this segment when heterozygous in different genetic backgrounds. Parents, isogenic hybrids, and unmodified hybrid controls were evaluated in three consecutive years of field study. The chm segment, when either homozygous or heterozygous, significantly increased soluble solids concentration by 13% and 12%, respectively, over VF145B-7879 (esc/esc), suggesting dominant gene action. Averaged across the three isohybrids and one isoline, one dose of this segment significantly increased soluble solids concentration by 6.0% compared to the unmodified hybrids and VF145B-7879. Other than increasing fruit total and soluble solids in mature-green and ripe-red tomatoes, no consistent negative effects of the chmielewskii segment were observed in the various genetic backgrounds on plant yield, fruit weight, or fruit pH. These results favor the use of this segment in breeding programs to develop fresh market and processing tomato cultivars with enhanced quality and reduced processed product dehydration costs. Received: 15 April 2000 / Accepted: 13 January 2001     

QTL analysis of agronomic traits in barley based on the doubled haploid progeny of two elite North American varieties representing different germplasm groups

A better understanding of the genetics of complex traits, such as yield, may be achieved by using molecular tools. This study was conducted to estimate the number, genome location, effect and allele phase of QTLs determining agronomic traits in the two North American malting barley (Hordeum vulgare L.) quality variety standards. Using a doubled haploid population of 140 lines from the cross of two-rowed Harrington×six-rowed Morex, agronomic phenotypic data sets from nine environments, and a 107-marker linkage map, we performed QTL analyses using simple interval mapping and simplified composite interval mapping procedures. Thirty-five QTLs were associated, either across environments or in individual environments, with five grain and agronomic traits (yield, kernel plumpness, test weight, heading date, and plant height). Significant QTL×environment interaction was detected for all traits. These interactions resulted from both changes in the magnitude of response and changes in the sign of the allelic effect. QTLs for multiple traits were coincident. The vrs1 locus on chromosome 2 (2H), which determines inflorescence row type, was coincident with the largest-effect QTL determining four traits (yield, kernel plumpness, test weight, and plant height). QTL analyses were also conducted separately for each sub-population (six-rowed and two-rowed). Seven new QTLs were detected in the sub-populations. Positive transgressive segregants were found for all traits, but they were more prevalent in the six-rowed sub-population.QTL analysis should be useful for identifying candidate genes and introgressing favorable alleles between germplasm groups. Received: 18 August 2000 / Accepted: 15 December 2000     

Microsatellite markers identify three additional quantitative trait loci for resistance to soybean sudden-death syndrome (SDS) in Essex × Forrest RILs

Resistance to the sudden-death syndrome (SDS) of soybean (Glycine max L. Merr.), caused by Fusarium solani f. sp. glycines, is controlled by a number of quantitatively inherited loci (QTLs). Forrest showed a strong field resistance to SDS while Essex is susceptible to SDS. A population of 100 recombinant inbred lines (RILs) derived from a cross of Essex × Forrest was used to map the loci effecting resistance to SDS using phenotypic data obtained from six environments. Six loci involved in resistance to SDS were identified in this population. Four of the QTLs identified by BARC-Satt214 (P = 0.0001, R²= 24.1%), BARC-Satt309 (P = 0.0001, R² = 16.3), BARC-Satt570 (P = 0.0001, R² = 19.2%) and a random amplified polymorphic DNA (RAPD) marker OEO2₁₀₀₀ (P = 0.0031, R²=12.6) were located on linkage group (LG) G (Satt309 and OEO2₁₀₀₀ were previously reported). Jointly the four QTLs on LG G explained 50% of the variation in SDS disease incidence (DI). All the QTLs on LG G derived the beneficial allele from Forrest. Two QTLs, BARC-Satt371 (P = 0.0019, R² = 12%) on LG C2 (previously reported) and BARC-Satt354 (P = 0.0015, R² = 11.5%) on LG I, derived their beneficial allele from Essex and jointly explained about 40% of the variation in SDS DI. Two-way and multi-way interactions indicated that gene action was additive among the loci underlying resistance to SDS. These results suggest that cultivars with durable resistance to SDS can be developed via gene pyramiding. Received: 19 January 2000 / Accepted: 30 April 2000     

Toward the mapping of physiological and agronomic characters on a rice function map: QTL analysis and comparison between QTLs and expressed sequence tags

We have constructed a rice function map by collating the results on quantitative trait loci (QTLs) for 23 important physiological and agronomic characters (including 13 newly measured traits) obtained using backcross inbred lines of japonica Nipponbare×indica Kasalath. Using these materials, The Rice Genome project (RGP) has developed a high-density genetic map. QTLs controlling yield did not overlap with those controlling the morphological and physiological traits supposed to relate to yield, such as photosynthetic ability. This result suggests that these traits do not influence yield, at least in this genetic background and environment. QTLs controlling yield also did not overlap with the structural genes controlling carbon metabolism (rbcS, cytosolic or plastidic fructose-1,6-bisphosphate, R-enzyme, and sucrose synthase).The combination of a function map and results from the RGP can be advantageous. The utility of this map is discussed. Received: 1 October 1999 / Accepted: 28 July 2000     

Sensitized polygenic trait analysis

Genetic variation in many biological processes and evolutionary adaptations is caused by polygenes – genes that act in combination to affect a particular trait. Despite the recent identification of several polygenes, many remain to be found, suggesting that new experimental and analytical methods are needed to facilitate their discovery. Here we discuss sensitized polygenetic trait analysis, a method that has emerged recently for simplifying the genetic analysis of polygenic traits. The method uses a known single gene mutation in linkage testing crosses to ‘sensitize’ the analysis. By increasing the frequency of affected individuals in segregating populations, linkages are more readily detected. This method has considerable potential, especially given the increasing variety of mutations that can be used to sensitize the genetic analysis of polygenic traits.     

Measuring and controlling data quality in biological assemblage surveys with special reference to stream benthic macroinvertebrates

1. Biological assemblage surveys primarily aim to characterise species composition and relative abundance at one or more spatial or temporal scales. Data interpretation and conclusions are dependent on how well samples characterise the assemblage of interest. 2. Conventional measures of data quality, e.g. standard deviations or coefficients of variation, were designed for single variable estimation, and they are either insufficient or invalid for assessing the quality of data describing entire assemblages. Similarity indices take species composition and relative abundance into account and may be used to effectively measure and control the quality of data used to characterise assemblage structure. 3. The average Jaccard coefficient (JC) calculated across multiple pairs of replicate samples, i.e. autosimilarity JC (AJC), is conceptually and numerically related to the average coefficient of variation in the densities of all species recorded, a measure of sampling precision, and to the proportion of total species richness sampled, a measure of sampling accuracy. 4. We explored how AJC can be used to assess the effect of different potential sources of error on the quality of assemblage survey data, including the sampling effort used both within regions and at individual sites, the individuals collecting samples, sub‐sampling procedures, and consistency of taxon identification. 5. We found that the autosimilarity‐based approach overcomes most weaknesses associated with conventional measures of data quality and can be used to effectively measure and control the quality of assemblage survey data.     

Strategies of plant breeding for improved rumen function

In general, breeding programmes directed at the improvement of forage have concentrated on easily measurable phenotypes such as yield, digestibility, resistance to lodging, etc. Selection programmes have improved forage production but historically have addressed relatively few quality considerations. In addition, selection for quality has been limited by availability of suitable analytical techniques. With the current emphasis on quality rather than quantity and the desire by the public for greater understanding about where their food comes from, quality considerations should be a greater target in future breeding programmes. This review briefly covers previous improvements in quality of grazed and silage forages and considers how new technologies might be employed to realise targets for future improvements. In particular we address the concept that interactions between rumen micro‐organisms and ingested plant material in the rumen are not static but are in fact dynamic. This has implications for post‐ingestion biology and feed utilisation.     

Combined effects of food quantity and quality on Cd, Cr, and Zn assimilation to the green mussel, Perna viridis

We examined the assimilation of Cd, Cr, and Zn by the green mussel Perna viridis under complicated food conditions, including combinations of different compositions and concentrations of food (diatom and sediment), and variable food quantity and quality during particle digestion. At different combinations of food composition and quantity (5 mg l⁻¹ and 20 mg⁻¹, below and above the pseudofeces production), the Cd assimilation was significantly dependent on the food composition. The Cd assimilation efficiency (AE) decreased with increasing proportions of sediments in the diets, but its assimilation was not significantly affected by food concentration. In contrast, the assimilation of Cr and Zn decreased significantly with increasing food concentrations, whereas food composition did not significantly affect their AEs. Variations in metal gut passage time accounted partially for the difference in AEs among different combinations of food composition and quantity. By changing the type of particles during metal digestion, their AEs were maintained comparably at a low particle load (1 mg l⁻¹), suggesting that variation of food quality during digestion did not affect metal assimilation. At a higher particle load (5 mg l⁻¹), variation of food type during digestion affected the AEs of Cr and Zn. An increase in food concentrations from 1 to 15 mg l⁻¹ during digestion resulted in a significant decrease in the AEs of Cr and Zn bound with either sediments or diatoms. Conversely, decreasing the food concentrations from 15 to 1 mg l⁻¹ did not affect the AEs of metals, except for Zn bound with diatoms. Overall, our results highlighted the metal-specificity in their assimilation as influenced by complicated food environments, probably caused by different metal geochemical and biological behavior in the mussels. Feeding selectivity may have a greater control on the influx rate into the mussels than metal assimilation.