Qualitative inheritance of water-stress induced apical sterility in wheat (Triticum aestivum)

Grain number per unit area is an effective component of grain yield in bread wheat. Water-stress induced apical sterility (tip sterility) reduces the number of grains and, consequently, the grain yield in semi-arid regions with a shortage of available water during the pre-anthesis period. Crosses between apical sterile and apical fertile varieties and selection lines were made and F1, BC1, and F2 populations were subjected to moderate water-stress to study the inheritance of this character. The F2 and BC1 plants were qualitatively categorised into two phenotypes and tested for monohybrid and dihybrid segregation hypotheses. All the spikes of F1 plants obtained from crosses between apical fertile and apical sterile varieties were fully fertile indicating apical fertility is dominant to apical sterility. The F2 segregation Results from crosses between apical fertile lines and Y82187 suggested two complementary dominant genes segregating independently were involved in tolerance to water-stress induced apical sterility. In other words, two dominant genes determine apical fertility in these crosses and if one of these loci is homozygous, recessive waterstress will induce apical sterility. One F2 population segregated for both apical sterility and vernalisation response. Semi-winter plants had more sterile spikelets and the result of chi-square test confirmed monhybrid segregation for vernalisation response.     

Dominance,overdominance and epistasis in Pisum sativum L.

Summary Dominant genes are the main cause of the heterosis induced by fasciated mutants of different lines of Pisum sativum. Most of these cases were originally interpreted by different authors as examples of monogenic overdominance. Several not-closely-linked genes appear to have mutated simultaneously in most of the fasciated lines. Although fasciation itself is recessive, other mutant characters, such as lateness, increased stem length (number and length of internodes) and, in part, seed production per plant, show dominant inheritance. The latter two features are, however, to a considerable extent suppressed in the fasciated lines by unfavourable gene-interactions (epistasis). Crossing these lines with non-fasciated ones shows that the epistatic genes are recessive and the dominant genes are then no longer hindered in their action. By eliminating the epistatic genes from the genomes of fasciated lines by recombination, the heterosis phenomenon has been fixed on six independent occasions for different lines. The fasciata genes themselves were found to be the most probable cause of these cases of recessive epistasis. The question whether different kinds of fasciation affect heterosis differently is examined. Recessive epistasis and dominance explain most of the quantitative distinctions between the different hybrids. In addition, one example of heterosis between non-fasciated lines is given and the possible meaning of the overall results for plant breeding and population genetics is mentioned.     

Developmental characterization of the fasciated locus and mapping of Arabidopsis candidate genes involved in the control of floral meristem size and carpel number in tomato.

Mutation at the fasciated locus was a key step in the production of extreme fruit size during tomato domestication. To shed light on the nature of these changes, near-isogenic lines were used for a comparative developmental study of fasciated and wild-type tomato plants. The fasciated gene directly affects floral meristem size and is expressed before the earliest stages of flower organogenesis. As a result, mature fruit of fasciated mutants have more carpels (locules) and greater fruit diameter and mass. The discovery that fasciated affects floral meristem size led to a search for candidate genes from Arabidopsis known to be involved in floral meristem development. Putative homologs were identified in a large tomato EST database, verified through phylogenetic analyses, and mapped in tomato; none mapped to the fasciated locus; however, putative homologs of WUS and WIG mapped to the locule number locus on chromosome 2, the second major transition to large tomato fruit, with WUS showing the highest association. In other cases, minor QTLs for floral organ number (lcn2.2) and (stn11.2) co-localized with a CLV1 paralog and with the syntenic region containing the CLV3 gene in Arabidopsis, respectively.     

Testing cms-P-linked AFLPs for selection of rye hybrid components

Application of AFLPs linked to pollen fertility restoration and non-performing genes evaluated in the C394-F2 hybrid was studied using a set of male sterile lines in the sterilising Pampa cytoplasm, several restorers and maintainer lines and, finally, two inbred lines backcrossed into cms-P, cms-R, cms-S and cms-C cytoplasms each. The set of male sterile lines based on the Pampa cytoplasm exhibited gradual variation in their ability to restore pollen fertility (starting from low and closing with high) in crosses with three unrelated restorers. Variations in the AFLPs between the analysed materials were observed, however, no clustering of the lines according to their sterile and fertile phenotypes was observed. The same markers, when applied to the population restorer (cv. Walet) that formed the C394-F2 cross permitted identification of plants with genotypes that could be recognized as restorers.     

The Chloroplast Function Database: a large‐scale collection of Arabidopsis Ds/Spm‐ or T‐DNA‐tagged homozygous lines for nuclear‐encoded chloroplast proteins,and their systematic phenotype analysis

A majority of the proteins of the chloroplast are encoded by the nuclear genome, and are post‐translationally targeted to the chloroplast. From databases of tagged insertion lines at international seed stock centers and our own stock, we selected 3246 Ds/Spm (dissociator/suppressor–mutator) transposon‐ or T‐DNA‐tagged Arabidopsis lines for genes encoding 1369 chloroplast proteins (about 66% of the 2090 predicted chloroplast proteins) in which insertions disrupt the protein‐coding regions. We systematically observed 3‐week‐old seedlings grown on agar plates, identified mutants with abnormal phenotypes and collected homozygous lines with wild‐type phenotypes. We also identified insertion lines for which no homozygous plants were obtained. To date, we have identified 111 lines with reproducible seedling phenotypes, 122 lines for which we could not obtain homozygotes and 1290 homozygous lines without a visible phenotype. The Chloroplast Function Database presents the molecular and phenotypic information obtained from this resource. The database provides tools for searching for mutant lines using Arabidopsis Genome Initiative (AGI) locus numbers, tagged line numbers and phenotypes, and provides rapid access to detailed information on the tagged line resources. Moreover, our collection of insertion homozygotes provides a powerful tool to accelerate the functional analysis of nuclear‐encoded chloroplast proteins in Arabidopsis. The Chloroplast Function Database is freely available at http://rarge.psc.riken.jp/chloroplast/ . The homozygous lines generated in this project are also available from the various Arabidopsis stock centers. We have donated the insertion homozygotes to their originating seed stock centers.     

通过小麦Ms2近等基因系的抑制缩减杂交分析揭示小穗和花药中差异表达基因

以Ms2近等基因系处于减数分裂期的可育小穗cDNA作为驱动因子(driver),以同一时期的不育小穗cDNA作为测验因子(tester)进行缩减杂交(SSH),将扩增后的缩减杂交产物进行克隆,构建了一个包含882个重组克隆的SSH文库.分别以可育小穗和不育小穗的cDNA为探针与SSH文库克隆进行反式Northern杂交,结果显示接近90%的克隆在不育小穗中呈上调表达.对文库中21个克隆插入片段的序列相似性分析表明其中有18个与来源于穗部或减数分裂期的花药cDNA同源.13个克隆的编码产物与已知功能的蛋白质同源,其中5个参与碳代谢活动,4个参与胞内分子的运输,2个蛋白产物参与染色体的构成及染色体的结构变化,1个是生长素抑制蛋白,1个是转录因子.用中国春缺体四体材料对9个克隆进行了染色体定位,其中一个克隆定位于第四染色体同源群,与Ms2所在的染色体同属一个同源群.通过搜索水稻的同源BAC(bacterial artificialchromosome)和PAC(P1 artificial chromosome)克隆,推测另外11个克隆的染色体位置,其中4个克隆可能位于第四染色体同源群.用RNA点杂交对11个克隆进行表达谱分析,其中8个克隆在不育株的小穗和花药中呈上调表达.     

Alcohol Dehydrogenase in the Diploid Plant STEPHANOMERIA EXIGUA (Compositae): Gene Duplication, Mode of Inheritance and Linkage

Study of the biochemical genetics of alcohol dehydrogenase (ADH) in the annual plant Stephanomeria exigua (Compositae) revealed that the isozymes are specified by a small family of tightly linked structural genes. One set of ADH isozymes (ADH-1) was induced in roots by flooding, and was also expressed in thickened unflooded tap roots, stems, ovaries and seeds. As in other plants, the enzymes are dimeric and form homo- and heterodimers. An electrophoretic survey of ADH-1 phenotypes in two natural populations revealed seven different ADH-1 homodimers in various phenotypes having one to eight enzyme bands. Genetic analysis of segregations from crosses involving 59 plants showed that the ADH-1 isozymes are inherited as a single Mendelian unit, Adh1. Adh1 is polymorphic for forms that specify one, two, or three different ADH-1 subunits (which combine to form homo- and heterodimers), and are expressed co-dominantly in all genotypic combinations. Staining intensity of enzymes extracted from various homozygous and heterozygous plants indicated that the different subunit types specified by Adh1 are produced in approximately equal amounts. These observations suggest that Adh1 is a compound locus consisting of one to several tightly linked (0 recombinants among 579 testcross progeny), coordinately expressed structural genes. The genes in the two triplications also occur in various duplicate complexes and thus could have originated via unequal crossing over. The ADH-2 isozyme found in pollen and seeds is apparently specified by a different gene, Adh2. Adh1 and Adh2 are tightly linked (0 recombinants among 81 testcross progeny).     

Development of transgenic rice pure lines by particle bombardment‐mediated transformation and genetic analysis‐based selection

Mature seed‐derived callus from an elite Chinese japonica rice cv. Eyl 105 was transformed with a plasmid containing the selectable marker hygromycin phosphotransferase (hpt) and the reporter β‐glucuronidase (gusA) genes via particle bombardment. After two rounds of selection on hygromycin (30 mg/l)‐containing medium, resistant callus was transferred to hygromycin (30 mg/l)‐containing regeneration medium for plant regeneration. Twenty‐three independent transgenic rice plants were regenerated from 127 bombarded callus with a transformation frequency of 18.1%. All the transgenic plants contained both gusA and hpt genes, revealed by PCR/Southern blot analysis. GUS assay revealed 18 out of 23 plants (78.3%) proliferated on hygromycin‐containing medium had GUS expression at various levels. Genetic analysis confirmed Mendelian segregation of transgenes in progeny. From R2 generations with their R1 parent plants showing 3:1 Mendelian segregation, we identified three independent homozygous transgenic rice lines. The homozygous lines were phenotypically normal and fertile compared to the control plants. We demonstrate that homozygous transgenic rice lines can be obtained via particle bombardment‐mediated transformation and through genetic analysis‐based selection.     

Inducing male sterility of tomato using two component system

Production of hybrid seeds and pursuing heterosis breeding of many crops have been accomplished using male sterile lines. However, not all crops have valuable male sterile lines due to instability of male sterility and absence of a restorer system. In this study, male sterile lines have been induced using a two-component system. The extracellular ribonuclease Barnase was cleaves into two inactive yet complementary fragments, designated as ??Bn-5?? and ??Bn-3??. Both components were controlled by a TA29 promoter. They were transferred into the tomato inbred line ??Yellow tomato?? by Agrobacterium method. Southern blotting identified that 11 transgenic Bn-5 plants (T₀) and 10 transgenic Bn-3 plants (T₀) were obtained. The vegetative phenotypes of all T₀ plants were similar to wild-type, and they were capable of producing viable pollen grains and normal fruit with seeds, indicating that Barnase had lost its function after it being split two partial fragments. After self-pollination, homozygous progenies (T₁) of transgenic Bn-5 and Bn-3 plants were chosen to cross each other, Barnase could be reconstituted and co-expressed in the same cell, which caused the hybrid plants to produce collapsed pollen grains with no viability and thus100?% male sterile plants were obtained. Stamens of male sterile plants were shorter than those of the wild type plants. PCR detection demonstrated that all male sterile plants contained Barnase, but male fertile plants did not. The male sterile plants were crossed with the male fertile inbred lines, and the result showed that hybrid (F₁) plants were capable of producing normal fruit with seeds, and their pollen grain fertility was restored. The co-segregation ratio of Bn-5 and Bn-3 fragments showed 1:1 among hybrid plants. In conclusion, the results verified that the male sterility could be generated by two component system and be used in hybrid seed production. The F₁ between the male sterile plant and the inbred line showed heterotic comparing to both parents. This system needs not breed restoration line.     

Several nuclear genes control both male sterility and mitochondrial protein synthesis in Nicotiana sylvestris protoclones

Summary Male sterile plants appeared in the progeny of three fertile plants obtained after one cycle of protoplast culture from a fertile botanical line and two androgenetic lines ofNicotiana sylvestris. These plants showed the same foliar and floral abnormalities as the cytoplasmic male sterile (cms) mitochondrial variants obtained after two cycles of culture. We show that male sterility in these plants is controlled by three independent nuclear genes,ms1, ms2 andms3, while no changes can be seen in the mitochondrial genome. However, differences were found between thein organello mitochondrial protein synthesis patterns of male sterile and parent plants. Two reproducible changes were observed: the presence of a new 20 kDa polypeptide and the absence of a 40 kDa one. Such variations were described previously in mitochondrial protein synthesis patterns of the cms lines. Fertile hybrids of male sterile plants showed normal synthesis patterns. The male sterile plants are thus mutated in nuclear genes involved in changes observed in mitochondrial protein synthesis patterns.     

A codominant molecular marker in linkage disequilibrium with a restorer-of-fertility gene (Ms) and its application in reevaluation of inheritance of fertility restoration in onions

To reveal the linkage relationship between the Ms locus, a restorer-of-fertility gene for cytoplasmic male-sterility (CMS) caused by CMS-S cytoplasm in onion (Allium cepa L.) and previously reported molecular markers linked to the Ms locus, 11 recombinants selected from 4,273 segregating plants originating from the cross between male-sterile maternal and male-fertile paternal lines were analyzed. Results showed that genotypes of a codominant marker, jnurf12, were perfectly matched with the male-fertility phenotypes in all recombinants, but that this marker was not applicable in diverse breeding lines due to multiple band patterns. For the development of more reliable markers, a 12-bp indel was identified from the sequences which were obtained by genome walking, and was used to develop a simple PCR marker which was designated jnurf13. When 104 diverse breeding lines containing CMS-S cytoplasm were analyzed with the jnurf13 marker, male-fertility phenotypes of all breeding lines were perfectly matched with marker genotypes. To our surprise, phenotypes of 153 breeding lines containing CMS-T-like cytoplasm were also matched with genotypes of the jnurf13 marker which was linked to the Ms locus for the CMS-S system. Furthermore, phenotypes of four F₂ populations containing CMS-T-like cytoplasm co-segregated perfectly with jnurf13 genotypes. Allelic segregation distortion was detected in two F₂ populations using the jnurf13 maker. The results of this study were in conflict with a previous model for inheritance of fertility restoration in the CMS-T system. Therefore, we proposed a new model based on the data analyzed with the jnurf13 marker, which was in linkage disequilibrium with restorer-of-fertility genes for both CMS systems.     

Collection of Arabidopsis thalianaMorphological Insertion Mutants

A collection of transgenic Arabidopsis thalianaplants has been obtained by Agrobacterium-mediated transformation. The genomes of the transgenic plants contain insertions of T-DNA of the vector plasmids pLD3 or pPCVRN4. Genes bearing T-DNA insertions were shown to constitute 12–18% of the total number of A. thalianagenes. Seventy-five lines have been chosen from the collection and subjected to genetic and molecular-genetic analysis. Of these, 5 were dominant mutants, and 70, recessive insertion mutants with various morphological defects. Identification of mutant phenotypes and genetic characterization of the transgenic lines have been performed with the use of nutrient media supplemented with exogenous hormones, which revealed five recessive lethal mutants and one dominant sterile mutant.     

Creation of a collection of morphological insertional mutants of Arabidopsis thaliana

A collection of transgenic Arabidopsis thaliana plants has been obtained by Agrobacterium-mediated transformation. The genomes of the transgenic plants contain insertions of T-DNA of the vector plasmids pLD3 or pPCVRN4. Genes bearing T-DNA insertions were shown to constitute 12-18% of the total number of A. thaliana genes. Seventy-five lines have been chosen from the collection and subjected to genetic and molecular-genetic analysis. Of these, 5 were dominant mutants, and 70, recessive insertion mutants with various morphological defects. Identification of mutant phenotypes and genetic characterization of the transgenic lines have been performed with the use of nutrient media supplemented with exogenous hormones, which revealed five recessive lethal mutants and one dominant sterile mutant.     

The use of rootless mutants for the screening of spontaneous androgenetic and gynogenetic haploids in Nicotiana tabacum: evidence for the direct transfer of cytoplasm

Summary In crosses between a homozygous rootless mutant line of Nicotiana tabacum used as female and other Nicotiana tabacum lines, androgenetic haploids can be directly selected by their ability to form plantlets with a normal rooting system, whereas hybrid plants are killed few weeks after sowing. These androgenetic plants have the nucleus of the male parent into the cytoplasm of the female parent. In crosses where the homozygous rootless mutant line is used as a pollen donor, gynogenetic haploids can also be directly selected. Haploids can therefore be derived from male sterile plants using this approach. A generalization of this system for direct cytoplasm transfer and for the screening of spontaneous haploids in dicotyledons is proposed.     

Cytoplasmic male sterility in Vicia faba L.

Summary In many higher plants, nucleo-cytoplasmic interactions lead to pollen abortion. In Vicia faba, cytoplasmic male sterility is unstable as the cytoplasm appears to shift from a sterile to a fertile state. In this report, five flower phenotypes are defined but the study is focussed on the progenies obtained from intermediate, semi-sterile plants with the same homozygous nuclear constitution during five successive generations. The results could be interpreted by quantitative modifications of at least four different kinds of cytoplasmic determinants.     

Karyological characterization of sugar beet gynogenetic lines cultured in vitro

Flow cytometry was used to screen ploidy levels in 47 cultured in vitro sugar beet gynogenetic lines of various origin and age, obtained after plant regeneration from unfertilized ovules. When donor plants were diploid, the majority of regenerants were found to have cells with 1C, 2C and 4C relative DNA content (mainly haploid and diploid) and there were large differences in the rate of spontaneous in vitro chromosome doubling between individual homozygous lines. Six ovule-derived lines regenerated from fertile and sterile diploid donors of forty-five lines were solid diploids from the very early stages of their in vitro cultivation, and thus could not be classified as doubled haploids. In the case of tetraploid donor plants, the gynogenetic regenerants demonstrated 2x-ploidy level. The results obtained in chimeric plants with both haploid and diploid cells indicated the possibility to overcome mixoploidy by their re-cultivation through generative shoot tip culture. The flow cytometry method confirmed data obtained by conventional microscopic chromosome counting in dividing leaf cells and was found very useful for screening of a large number of regenerants and for characterizing the process of in vitro gynogenetic lines formation in sugar beet.     

一个新的小麦核不育材料的发现和鉴定

从轮选可育株衍生的后代中发现一个雄性不育株,即P740不育材料。在P7 40不育材料第1、2、3次姊妹交后代中,可育株与不育株的分离比分别符合4:1、 7:5和15:13。在第2次姊妹交后代中可育株产生的40个株系中,7个株系的育性分离比是15:1,33个株系是3:1,二者约分别占1/7和6/7。以上结果表明,P740是一个双隐性基因控制的核雄性不育材料。本文提出了计算隐性核不育材料姊妹交后代育性分离比率的公式。 Abstract:A male sterile material was found in the progeny derived from a fertile plant in the population of recurrent selection.The ratios of fertile to sterile plants in three sib-mating of the male sterile material with fertile plants were to 4:1,7:5 and 15:13,respcctively.In the 40 plant lines derived from the fertile plants of second sib-mating population,33 lines approximated to the segregation ratio of 3(fertile):a double recessive nuclear male sterile material.A genetic pattern for calculation of fertile segregation in sib-mating progenies of recessive nuclear male sterile material was advanced in this paper.     

Ultraviolet mutagenesis and genetic analysis of resistance to methylglyoxal-bis (guanylhydrazone) in tobacco

Summary We have isolated cell lines of Nicotiana tabacum resistant to methylglyoxal-bis(guanylhydrazone) (MGBG), a potent inhibitor of S-adenosylmethionine decarboxylase. We obtained 31 resistant lines from ultraviolet light mutagenized cultures, representing at least 13 independent events. No resistant lines were obtained from non-mutagenized control cultures. The increase in mutation rate due to the ultraviolet light treatment was 22 to 62 fold increased over an estimate of the maximum possible spontaneous rate. In reconstruction experiments we reselected resistant cell lines from varying dilutions into a background of a constant concentration of wild type cells; at the minimum ratio of resistant cells to wild type cells, 1:125,000, we recovered resistant colonies at an estimated plating efficiency of 12.5%. A number of resistant lines have been regenerated into plants. All of the ones that flowered are male sterile, sometimes associated with morphological transformations. Some are female sterile as well. Meiotic genetic analysis of one resistant line, Mgr12, suggests that the MGBG resistance is segregating as a nuclear dominant trait. The male sterility and abnormal floral development of Mgr12 cosegregate with the MGBG resistance, suggesting the two phenotypes are coincident.     

Gene-ecological investigations in Pisum mutants

Summary Six mutants and nine recombinants of Pisum sativum were grown along with the mother variety at Kurukshetra, North India. The findings obtained were compared with those obtained for the same material grown at Bonn, Germany. The following observations were made.Stem length and degree of branching are influenced differentially in the various genotypes tested in India as a consequence of a specific reaction of the genes to the climatic conditions. A gene for weak stem fasciation and gene efr for earliness in a specific gene combination are unable to express their action in North India whereas they are fully active in Germany. Furthermore, in Kurukshetra early flowering of some recombinants does not result in early ripening because their seeds require about double the time for full ripening than those of the mother variety.At Kurukshetra, recombinant R 674A proved to be highly heat susceptible. All the plants died in early stages of ontogenetic development. Four other genotypes died due to heat before completing seed ripening. One mutant and three recombinants were found to be more tolerant to powdery mildew attack than the mother variety and Indian local lines. The seed production of eight genotypes in relation to that of the initial line was essentially better in North India than in Germany. They are obviously better adapted to the semi-arid conditions. Some of them appear to be useful for pea breeding in India. In contrast, a fasciated mutant, high yielding in Germany, is not able to express this potentiality at Kurukshetra. At Udaipur (Rajasthan, Western India), this mutant is unable to flower. Another four genotypes, tested at both Indian locations, exhibited an essentially poorer seed production at Udaipur than at Kurukshetra due to some ecological factors.The findings indicate a specific response of some of the genotypes tested to the specific ecological conditions of the three locations, their response differing from that of the mother variety demonstrating thereby a different adaptational optimum.     

远缘杂交油菜核不育系的创建及其细胞学和形态学研究

在甘蓝型油菜与诸葛菜以及芥菜型油菜与诸葛菜属间杂交后代中分别发现1个和3个不育材料,经杂交和多代近交育成了相应的甘蓝型油菜不育系。通过对核不育系体细胞鉴定表明,所有新发现的不育系染色体数为38,均已恢复到甘蓝型油菜。这些不育系绝大部分花粉母细胞（PMC）在中期Ⅰ、后期Ⅰ和后期Ⅱ 3个时期染色体行为表现正常,但不同时期的PMC均会出现一定比例的异常现象,主要表现为染色体落后或染色体桥等。这些不育系属于单核败育型,不育株与可育株的花器形态差异明显,不育系还存在不同程度的死蕾等特点。通过对花器生长过程的研究,发现不育株雌蕊生长随雄蕊败育进程逐渐加快,而可育株雌蕊生长则存在两个生长缓慢阶段。此外,文章还讨论了这些不育系的应用前景。