Inbred lines with dominant incompatibility alleles for use as parents of F1 hybrid brussels sprouts

Summary To improve the chances of obtaining highly self-incompatible inbred lines for use as parents of F₁ hybrid Brussels sprouts and to extend the range of mutually cross-compatible combinations available, new inbred lines are being produced from plants selected for the presence of dominant S-alleles. The material comprises 42 different inbred families representing 15 cultivars and contains 12 dominant S-alleles of uncommon occurrence in Brussels sprouts. Data on S-allele interactions in the material are presented.Tests showed that whilst many of the parent plants containing dominant S-alleles were highly self-incompatible, a few had only weak self-incompatibility. Although the chances of obtaining strongly self-incompatible inbreds may be increased by using material with dominant S-alleles, it remains necessary to test and select for strong self-incompatibility during the breeding programme.Production of such inbred lines requires the application of two independent selection procedures, one for agronomic type and one for S-allele constitution. Only a small proportion of the plants of a parent cultivar are acceptable on both counts. Thus large populations of the cultivar and large numbers of selections are necessary: this in turn involves much expensive S-allele screening. To alleviate this problem a wide-based panmix containing only dominant S-alleles is being produced. It is hoped that from this it will be possible to extract inbred lines which carry only dominant S-alleles, so avoiding the need to screen each parent plant for its S-allele content.     

应用单雌系F2代法检测棉铃虫对转Bt基因棉抗性等位基因的频率

用单雌系F2代遗传方法检测了棉铃虫对转Bt基因棉(新棉33B)Bt毒素蛋白的抗性等位基因频率.研究结果表明,河北邱县转Bt基因棉新棉33B只种植1年的情况下,棉铃虫自然种群中抗性等位基因的频率＞5.8×103,该方法的灵敏度比区分剂量法和机率分析(抗性倍数)法高一个数量级以上.文章还对转Bt基因棉种植区棉铃虫的抗性监测和治理进行了讨论.     

Genetics of isozyme variants in Populus tremula,P. tremuloides and their hybrids

Summary Eight Populus tremula and six P. tremuloides clones as well as 49 full-sib families were studied in GOT, LAP, 6-PGDH, and SKDH by horizontal starch gel electrophoresis. For GOT one polymorphic zone was found and segregation of seven full-sib families suggests Mendelian inheritance. For LAP and 6-PGDH two zones each were clearly scored. For LAP two polymorphic loci were proposed based on the phenotypic segregation of isozyme variants in six and 34 full-sib families, respectively. In 24 full-sibs families the presence of null alleles was inferred for both loci. The genetic control of the upper zone of 6-PGDH was demonstrated by a segregation analysis of 17 full-sib families. SKDH also demonstrated a Mendelian inheritance pattern in 12 of the full-sib families analysed. The electrophoretic patterns of pollen were similar to those of buds, but migration rates of the supposed corresponding isozymes were slightly modified (Lap-B, Skdh, 6Pgdh-A). Lap-A was not present in pollen extracts and hybrid bands were not found when gels were stained for dimeric enzymes (6-PGDH, GOT).     

Allelic relationships of genes controlling number of flowers per axis in chickpea

Genetic variation for number of flowers per axis in chickpea (Cicer arietinum L.) includes single-flower, double-flower, triple-flower and multi-flower traits. A double-flowered (DF) line ICC 4929, a triple-flowered (TF) line IPC 99-18 and a multi-flowered (MF) line JGM 7 were intercrossed in all possible combinations and flowering behavior of parents, F₁s and F₂s was studied to establish allelic relationships, penetrance and expressivity of genes controlling number of flowers per axis in chickpea. The F₁ from ICC 4929 (DF) × IPC 99-18 (TF) cross were double-flowered, whereas F₁ from ICC 4929 (DF) × JGM 7 (MF) and IPC 99-18 (TF) × JGM 7 (MF) crosses were single-flowered. The F₂ from ICC 4929 (DF) × IPC 99-18 (TF) cross gave a good fit to a 3:1 ratio for double-flowered and triple-flowered plants. The F₂ from ICC 4929 (DF) × JGM 7 (MF) cross segregated in a ratio of 9:3:3:1 for single-flowered, double-flowered, multi-flowered and double-multi-flowered plants. The F₂ from IPC 99-18 (TF) × JGM 7 (MF) cross segregated in a ratio of 9:3:4 for single-flowered, triple-flowered and multi-flowered plants. The results clearly established that two loci control number of flowers per axis in chickpea. The double-flower and triple-flower traits are controlled by a single-locus (Sfl) and the allele for double-flowered trait (sfl ^d ) is dominant over the allele for triple-flower trait (sfl ^t ). The three alleles at the Sfl locus has the dominance relationship Sfl > sfl ^d > sfl ^t . The multi-flower trait is controlled by a different gene (cym). Single-flowered plants have dominant alleles at both the loci (Sfl_ Cym_). The double-flower, the triple-flower and the multi-flower traits showed complete penetrance, but variable expressivity. The expressivity was 96.3% for double-flower and 76.4% for double-pod in ICC 4929, 81.2% for triple-flower and 0.0% for triple-pod in IPC 99-18, and 51.3% for multi-flower and 24.7% for multi-pod in JGM 7. Average number of flowers per axis and average number of pods per axis were higher in JGM 7 than double-flowered line ICC 4929 and triple-flowered line IPC 99-18. The results of this study will help in development of breeding strategies for exploitation of these flowering and podding traits in chickpea improvement.     

Determination of incompatibility genotypes in almond using first and second intron consensus primers: detection of new S alleles and correction of reported S genotypes

The work aimed to develop a reliable and convenient PCR approach for determining incompatibility S genotypes in almond. Initially, genomic DNAs of 24 accessions of known S genotype were amplified with novel consensus primers flanking the first and second introns of the S‐RNase gene. The PCR products separated on agarose showed length polymorphisms and correlated well with the reference alleles S1‐S₂3 and Sf. In addition, to improve discrimination between alleles of similar sizes, the same sets of primers but fluorescently labelled were used, and the products sized on an automated sequencer. These fluorescent primers were particularly informative in the case of the first intron, variation in the length of which has not been used previously for S genotyping in almond. Some reference alleles showed the same patterns with first and second intron primers, and others showed a microsatellite‐like trace. Subsequently, the S genotypes of 26 cultivars not genotyped previously and of four of uncertain genotype were determined. An allele described in Australian work as putative S₁₀ was shown to be a ‘new’ allele and ascribed to S₂₄ and evidence of five more ‘new’S alleles was found, for which the labels S₂₅‐S₂₉ are proposed. This PCR approach should be useful for genotyping in other Prunus crops.     

Variation and inheritance of erucic acid content in Brassica carinata germplasm collections from Ethiopia

Ethiopian mustard possesses a number of agronomic advantages over other oilseed crops with similar ecological adaptation in Ethiopia. However, its high erucic acid content is undesirable for a vegetable oil. Although efforts have been made to improve its quality, much has to be done to use natural variations that might exist within the species for fatty acid contents. This project was undertaken to study the variability of fatty acid contents, primarily erucic acid, in germplasm collections of Ethiopian origin, with an attempt to develop low (zero) erucic acid genotypes. The study used inbred lines as well as F₂ populations of 10 crosses between six parental lines. A wide variation in fatty acids was found. Oleic acid content varied from 5 to 34% and erucic acid content from 6 to 51%. Linoleic and linolenic acid contents were less variable. The high‐oleic genotypes exhibited not only low erucic but also higher linoleic (25%) and considerably lower linolenic acid (8%) contents. It was possible to classify the F₂ populations with the lowest erucic acid into three distinct classes. While the first class had an erucic acid content of 6–12%, the second and third classes had contents of 18–32% and 36–42%, respectively. The existence of a multiple allelic series of erucic acid in Ethiopian mustard would enable its fixation at zero levels without necessarily going into interspecific crossing.     

柑橘大实蝇微卫星标记的筛选

【目的】筛选可用于柑橘大实蝇（Bactrocera minax）种群遗传研究的微卫星标记。【方法】选取33对柑橘大实蝇同属种柑橘小实蝇（B. dorsalis）、木瓜实蝇（B. papayae）、瓜实蝇（B. cucurbita）、东澳番茄实蝇（B. cacuminata）中多态性较好微卫星引物,通过对PCR扩增产物进行琼脂糖电泳初筛选及变性聚丙烯酰胺凝胶电泳再筛选,并对其等位基因频率、多态信息含量和有效等位基因数等指数进行分析。【结果】33对微卫星引物中有12对引物对柑橘大实蝇有扩增条带,其同源率为36.4%。6个微卫星位点在柑橘大实蝇上共检测到 23个等位基因,平均等位基因数为3.83 个;6对微卫星引物的平均多态信息含量（PIC）为0.2248,最高为0.4105,最低为0.0869。【结论】所筛选出的6对微卫星引物表现出较好的多态性,可用于后续对柑橘大实蝇的种群遗传研究。     

芥黄蜜环菌交配型复等位基因的研究

从大兴安岭长白山采集17号芥黄蜜环菌,用分离的单孢菌株进行交配型测定,证实中国该种为双因子异宗配合机制,选取各号标本的4种交配型菌株进行循环配对实验,结果发现该种的交配型基因座的多样性很高,共有13对复等位基因,证明该种在世界分布区域内具有较强的生态适应能力。是目前国际首次用实验测定的蜜环菌交配基因数目     

微卫星标记BM3413和OB2在5个绵羊群体中多态性的研究

选萨福克羊、德国美利奴羊、特克塞尔羊、乌珠穆沁羊以及右玉本地绵羊5个绵羊群体共250只,通过耳组织提取基因组DNA,用2对微卫星引物进行PCR扩增,通过电泳分型、凝胶成像系统分析各位点等位基因及全部个体的标记基因型,计算基因频率、多态信息含量（PIC）和杂合度等,从分子水平上分析5个绵羊品种的遗传多态性。结果表明：BM3413和OB2这2个位点的等位基因数分别为7和8,多态信息含量PIC〉0.5,杂合度为0.827 1～0.846 7,均属于高度多态性位点,用于作为与生产性能相关的遗传标记是较理想的。     

4对微卫星DNA标记在3个绵羊品种中多态性的研究

选用无角道塞特、萨福克与中国美利奴肉羊品种群体,耳组织提取基因组DNA,用4对微卫星引物进行PCR扩增,通过电泳分型、凝胶成像系统分析各位点等位基因及全部个体的标记基因型,计算基因频率、多态信息含量(PIC)和杂合度等,从分子水平上分析4个位点的遗传多态性.结果表明,CSSM18,OB2,MCM38,MCMA26这4个位点的等位基因数分别为14、15、13、13,多态信息含量(PIC)丰富,杂合度高,均属于高度多态性位点,用于作为与生产性能相关的遗传标记是较理想的.