Frequency — dependent advantage in wheat

Summary The effect of frequency-dependent advantage in wheat was investigated by growing F₁. hybrid seeds of the crosses (Warimek X Halberd) and (Wariquam x Halberd) in a stand of Halberd at 5 frequencies: 4 %, 6.25 %, 11.11 %, 25 % and 50 %. A reduction of 35 % to 40 % in grain yield of individual plants was observed with both hybrids as their frequencies changed from 4% to 50 %. A similar trend with frequency was noted for several other plant characteristics, including total grain number, particularly with those measured towards the end of the growing season. Halberd plants did not show a corresponding increase as their frequency declined from 96 % to 50%. — The following season, 76 F₄ lines from the cross (Warimek X Halberd) and 70 F₄ lines from (Wariquam x Gabo) were grown at frequencies of 6.25% and 18.75% in machine sown stands of Wariquam and Halberd, respectively. Again grain yield decreased as genotypic frequency increased. Furthermore, there was a positive correlation between frequency-dependent advantage and relative grain yield, suggesting that high yielding genotypes show a greater advantage at low frequencies than lower yielding ones.     

Chromosome distribution and catenation in Rhoeo spathacea var. concolor

The twelve chromosomes of Rhoeo spathacea variety concolor are arranged in a definite sequence in a ring at meiosis. Identification of all the 12 chromosomes was possible in 119 diakinesis and metaphase I cells. — Pollen viability was measured to be 36.54% by cotton blue staining procedure. Forty five of 56 metaphase I cells (80.36%) had adjacent distribution. Each of the 12 chromosomes was equally likely to be involved in adjacent distribution regardless of their sizes and heterobrachialness. Adjacent distribution occurred randomly at each arm-position in the ring regardless of the lengths of the arm-pairs. — The most frequent chromosome configuration at diakinesis and metaphase I was a chain-of-12 chromosomes (41.18%). Cells with 1 to 4 chains of chromosomes were observed. The observed frequencies of various configurations were in good agreement with the calculated frequencies. The mean number of chiasmata was 10.90 per cell and 0.908 per pair of chromosome arms. The 131 chiasma failures were distributed at random among the 12 arm-positions. Since the lengths of arm-pairs in the ring vary, the randomness may mean that chiasma formation was limited to short terminal segments on all chromosomes.     

Cytogenetics of inherited partial sterility in three generations of the large milkweed bug as related to holokinetic chromosomes

AdultOncopeltus fasciatus males were irradiated with 9000 R of X-rays, and crossed to untreated females. Fertility was reduced to 4.1%. F₁ males and F₂ and F₃ males and females were outcrossed to untreated partners. All F₁ males were partially or totally sterile and a significant number of F₂ and F₃ males and females had reduced fertility. The fertility of each generation was higher than the preceding one, even though the progeny studied in the 3rd generation were selected mostly from low-fertility lines. Cytogenetic studies showed that complex chromosome rearrangements and fragments were transmitted to each generation and were severe enough to account for reduced fertility. — The transmission of complex chromosome rearrangements and fragments for 3 generations of outcrossing correlates with the persistence of sterility in this species possessing holokinetic chromosomes. — Over half the inviable embryos derived from irradiated sperm from P₁ males died in the early stages of development. The inviable embryos produced in later generations died in much later stages of development. — A stable rearrangement of a Y-chromosome fragment translocated to an autosome was isolated from a single F₁ male. This rearrangement was transmitted to all F₂ and F₃ sons. Fertility of the males of this line was reduced to about 75–80%.Supported in part by AEC Contract No. AT(49-7)3028.     

Selection indices for quality evaluation in wheat breeding

Summary From multilocation trials involving 125 cultivars of wheat of mainly French and European origin four tests — protein content, Pelshenke, modified Zeleny and the mixograph — were used to establish six selection indices. Three of these indices — IW₁, IW₂ and IW₃ — were calculated in order to evaluate the genetic potentiality of the lines for dough strength as given by the Chopin alveograph. The indices IV₁, IV₂ and IV₃ were established to evaluate loaf volume as measured by the French bread-making standard. A quality index IQ was calculated from the allelic effects of the high-molecular-weight (HMW) subunits of glutenin from 195 cultivars assessed by the Chopin alveograph and the Pelshenke test. Comparison of the relative efficiency of each of the six indices to the individual tests revealed the superiority of the indices over one or several technological parameters. The six selection indices and the quality index were compared using 30 very diverse F₄ lines. Their ability to retain the good quality lines is discussed in particular.     

Inheritance of Semidwarfism in Rice, ORYZA SATIVA L

The inheritance of plant height was investigated in a ten-parent diallel cross of diverse rice cultivars. Parents included two tall japonica lines and eight semidwarf lines. Data from parent, F₁, F₂ , and F₃ generations indicated that the majority of height variation among the ten parents could be accounted for by three major genes with additive loci effects. D51, 72/2234–11, and G33 (derived from the known major-gene indica semidwarf Dee-geo-woo-gen) all were found to possess an allelic, partially recessive semidwarfing gene (sd₁). Additional semidwarfing genes were detected in D66 (sd₂, fully recessive) and in CI 9858 (sd₃, partially to fully recessive). Relative magnitudes of additive effects were sd₁ > sd₂ ≥ sd₃. Hokuriki 76, Tedoriwase, and IV 29–4 were found to be dwarfed by a multiple-gene system. Hayman-Jinks diallel cross analysis on parent and F₁ information (1974 and 1975) and on parent and F₂ information demonstrated the presence of significant additive and dominance variation, but epistasis was not detected. A preponderance of dominant alleles with partial dominance for increased plant height was observed. Since diallel statistics reflect properties of genes with larger effects, the genetic model proposed from segregation analysis was in substantial agreement with predictions of the Hayman-Jinks analysis.     

The semidwarf gene,sd-1, of rice (Oryza sativa L.). II. Molecular mapping and marker-assisted selection

To establish the location of the semidwarf gene, sd-1, the anthocyanin activator (A), purple node (Pn), purple auricle (Pau), and the isozyme locus, EstI-2, in relation to DNA markers on the molecular linkage map of rice, 20 RFLP markers, previously mapped to the central region of chromosome 1 (McCouch et al. 1988), were mapped onto an F₂ population derived from the cross Taichung 65 (A,Pn,Pau)/Taichung 65 (sd-1). sd-1 and EstI-2 were determined to be linked most tightly to RFLP markers RG 109 and RG 220, which cosegregated with each other. The distance between these RFLP markers and sd-1 was estimated to be 0.8 cM, based on an observed recombination value of 0.8%. The order of genes and markers in this region of chromosome 1 was determined to be sd-1 — (EstI-2 — RG220 — RG109) — RG381 — A — Pn — Pau. To test the efficacy of selection for sd-1 based on these linked markers, 50-day-old F₂ seedlings derived from another cross, Milyang 23/Gihobyeo, were analyzed for marker genotype. At this age, the semidwarf character could not be clearly detected based on phenotype. In addition, plant height was normally distributed in this population, making it difficult to unambiguously identify plants carrying sd-1. Thirteen seedlings homozygous for the sd-1-associated allele at EstI-2, RG220 and RG109, and 13 seedlings homozygous for the Sd-1-associated allele at all three marker loci were selected for further genetic analysis. At 20 days after heading, the culm lengths of these 26 plants were measured and the expected phenotype was confirmed in every case. These 26 plants were then selfed for four generations and F₆ lines were again evaluated to determine whether any recombination among the three molecular markers, or between these markers and the sd-1 gene, could be detected. No recombinants were identified, confirming the tight linkage of these loci and the usefulness of genotypic selection for this recessive semidwarf character prior to the time when it can be evaluated based on phenotype.     

Inheritance of legumin and albumin contents in a cross between round and wrinkled peas

Summary Legumin and albumin are the fractions of pea seed proteins preferred to vicilin because of their high sulfur amino acid contents. The joint inheritance of legumin and albumin contents was studied in a cross between to contrasting lines of peas — one with high legumin and low albumin, and the other with low legumin and medium to high albumin. Single seed determinations were made in the parental, F₁; F₂ and backcross generations using rocket immunoelectrophoresis. In the non-segregating generations (P₁, P₂ and F₁), legumin and albumin contents were negatively correlated (r=–0.50). The estimates of correlation coefficients in the segregating generations (F₂, BC₁ and BC₂) were also about –0.5. However, the two estimates based on the round and on the wrinkled seeds separately in the F₂ generation were not significantly different from zero. At least four individual round F₂ seeds showed the desired recombination of high legumin with high albumin indicating that the unfavorable correlation can be broken. In this cross legumin content showed predominantly additive genetic variation whereas the dominance variance was the largest component for albumin content. A combined relative sulfur index, proposed as a convenient measure for selection, showed a narrow sense heritability of 47%. In general these results support the view that sulfur amino acid content of peas can be improved by breeding, but that the required selection regime must take both legumin and albumin content into account.     

Transmission of duplication-deficiencies from cotton translocations is unrelated to map lengths of the unbalanced segments

Adjacent-1 duplication-deficiencies (dp-dfs) are readily recovered from most heterozygous translocations in Gossypium hirsutum L., but frequencies of specific cytotypes differ widely in progenies from heterozygote (♀) x standard crosses. Surprisingly, these frequencies seem to be unrelated to the primary (postmeiotic) frequencies predicted by metaphase I configurations or to the proportion of the chromosome arm that is duplicate or deficient. Deficiencies and duplications from different translocations involving the same arm, as well as the two complementary dp-dfs from the same translocation, seldom exhibit similar frequencies. We conclude that the frequency of each of 101 different adjacent-1 cytotypes is largely idiosyncratic and may depend in part on interactions between the specific chromosome regions that are respectively trisegmental and monosegmental. Few, if any, of these interactions can be between homoeologues of the A_h and D_h genomes. Adjacent-2 dp-dfs are seldom recovered, even if they involve chromosomes that are readily tolerated in monosomic condition. Comparison of monosomes and telosomes with deficiencies suggests that some chromosomes and chromosome regions may be more dosage-sensitive than others, but their identification is not strongly supported by these data.     

Extensive heterozygosity at three enzyme loci in hybrid sunfish populations

Hybrid populations of sunfishes were produced in two different ponds, and the frequencies of allelic isozyme phenotypes were determined for three enzyme systems—malate dehydrogenase (NAD), esterases, and tetrazolium oxidase—in order to estimate the extent of heterozygosity at four different genetic loci. Interspecific F₁ hybrid fry (red-ear male × bluegill female) were produced in vitro. These fry were stocked in ponds at the free-swimming stage. When 1 year old, the F₁ hybrids produced a large F₂ hybrid population. Successful hybrid reproduction occurred each year thereafter. In one pond, a 1-year-old F₂ population exhibited all three isozyme phenotypes (red-ear, F₁, bluegill) at most loci in the approximate ratio of the 1:2:1 expected. In a second pond, 5-year-old individuals of the F₂ generation were morphologically like the F₁ and were all heterozygous for the enzyme loci studied. This unusual degree of heterozygosity in the older F₂ population appeared to be the result of differential survival of mature heterozygous individuals and not the result of early embryonic lethality. The increased heterozygosity at these unlinked loci was assumed to reflect the condition at other genetic loci in the F₂ hybrids. Several possible mechanisms are advanced to explain this apparent heterosis.This research was supported by NSF grant GB-16425 (G.S.W.) and by funds from the Illinois Natural History Survey (W.F.C.).     

Determination of prostaglandin F in blood plasma using chemically modified bacteriophage technique

The levels of prostaglandin F found in human and rabbit plasma were determined by the chemically modified bacteriophage assay.Prostaglandin F₂α was coupled covalently to bacteriophage T4 using carbodiimide as cross linking agent and the conjugated phage could be inactivated by anti-prostaglandin F₂α antibodies. Prostaglandins specifically inhibited the modified phage inactivation caused by antiserum and as little as 200 picograms of prostaglandin F₂α could be detected by this system. Anti-prostaglandin F₂α antibodies had a high specificity toward prostaglandin F₂α and exhibited a very low degree of cross reaction to the other prostaglandin derivatives. The concentration of the extracted prostaglandin F₂α from the plasma containing exogenous prostaglandin F₂α could be determined with a high recovery.In normal human males and in male rabbits, 0.300.82 and 0.421.22 nanograms of prostaglandin F per ml of plasma were found, respectively. These levels of prostaglandin F in plasma agree with those determined by the radioimmunoassay.     

Genetic studies of corn (Zea mays L.) anther culture response

Summary Anthers of two maize (Zea mays L.) inbred lines, DBTS (P₁) and B73 (P₂), their F₁, F₂ and first backcross generations — F₁ x DBTS (B₁), and F₁ x B73 (B₂) — were float cultured in YP medium to study the inheritance of corn anther culturability using generation mean analysis. Significant effects of generation were observed for the three traits measured: anther response (%), frequency of embryos (%) and anther productivity. Variation among the generations was similar for anther response and frequency of embryos: no significant differences were found among the P₁, F₁, F₂ and B₁ means, but the means of P₂ and B₂ were significantly lower than those of the other generations. For anther productivity, the F₂ generation tended to have a slightly higher tendency for multiple embryo formation. A simple additive-dominance model was adequate in explaining the inheritance of anther response and frequency of embryos, but digenic epistasis (additive x dominance) was involved in the inheritance of anther productivity. Additive genetic variance was higher than non-additive genetic variance for all the traits; however, only environmental variance was significant. Narrow-sense heritability estimates were 65% and 75% for anther response and frequency of embryos, respectively. Significant inter-plant variation was observed within generations, even for the inbred line DBTS, but isozymic analysis involving five enzyme loci did not reveal any genotypic variability within the inbred lines DBTS and B73.     

Single tester triple test cross analysis in spring wheat

Summary Two experiments, each including the same 30 homozygous varieties of spring wheat plus one separate tester variety, were conducted in order to detect epistasis and to test and estimate the additive and dominance components of genetic variation for five quantitative traits: final plant height, spike length, number of spikelets per spike, 100-kernel weight and grain yield per plant. Epistasis played a significant role in the control of 100-kernel weight and yield per plant. There was a gratifyingly good agreement between the two independent methods (2¯B₁i — ¯f_1i — ¯P_i and 2¯B_ci — ¯F_1i) used to test the presence of epistasis. In both experiments, there was a remarkably uniform high dominance ratio for most of the traits studied indicating that this test cross design is equally sensitive to both additive and dominance genetic variation.     

The recombination landscape and multiple QTL mapping in a Solanum tuberosum cv. ‘Atlantic’-derived F1 population

There are many challenges involved with the genetic analyses of autopolyploid species, such as the tetraploid potato, Solanum tuberosum (2n = 4x = 48). The development of new analytical methods has made it valuable to re-analyze an F₁ population (n = 156) derived from a cross involving ‘Atlantic’, a widely grown chipping variety in the USA. A fully integrated genetic map with 4285 single nucleotide polymorphisms, spanning 1630 cM, was constructed with MAPpoly software. We observed that bivalent configurations were the most abundant ones (51.0~72.4% depending on parent and linkage group), though multivalent configurations were also observed (2.2~39.2%). Seven traits were evaluated over four years (2006–8 and 2014) and quantitative trait loci (QTL) mapping was carried out using QTLpoly software. Based on a multiple-QTL model approach, we detected 21 QTL for 15 out of 27 trait-year combination phenotypes. A hotspot on linkage group 5 was identified with co-located QTL for maturity, plant yield, specific gravity, and internal heat necrosis resistance evaluated over different years. Additional QTL for specific gravity and dry matter were detected with maturity-corrected phenotypes. Among the genes around QTL peaks, we found those on chromosome 5 that have been previously implicated in maturity (StCDF1) and tuber formation (POTH1). These analyses have the potential to provide insights into the biology and breeding of tetraploid potato and other autopolyploid species.Subject terms: Polyploidy in plants, Genetic linkage study, Quantitative trait, Plant breeding     

Synergistic promotion of gibberellin and cytokinin on direct regeneration of floral buds from in vitro cultures of sepal segments in sinningia speciosa hiern

Summary This study reports the direct regeneration of flower buds from cultured sepal segments of Sinningia speciosa Hiern. Two types of floral bud regeneration were observed: regeneration of floral buds only (designed as B^F) and regeneration of both floral and vegetative buds (designed as B^F+V). The capacity of B^F regeneration was closely related to the location of sepal segments and the concentration of exogenous gibberellin (GA₃) and cytokinin in the medium. On the medium containing 1.0mgl^−1 GA₃, the addition of 6-benzyladenine (BA) significantly increased the frequency of total flower bud (B^F+B^F+V) formation, with the frequency up to 91.5% in the presence of 0.4mgl^−1 BA. On the medium containing 0.1mgl^−1 BA, the addition of GA₃ also increased the frequency of total flower bud regeneration, with the frequency up to 74.3% in the presence of 1.0mgl^−1 GA₃, but no further increase in regeneration was observed when the GA₃ concentration was higher than 1.0mgl^−1. The capacity of B^F regeneration from different locations of sepal segments was differential. The adaxial part of sepal segments gave rise to the highest frequency of 56.7 and 84.3% for B^F and B^F+B^F+V, respectively.     

Studies on trisomics in a Jute hybrid

Fifteen red pigmented trisomics were isolated in the F₂ generation from the cross Corchorus olitorius L. x C. capsularis L. In the F₃ generation a few green trisomics were obtained; more of these were isolated from the backcross generation. A detailed morphological and cytological analysis of the trisomic hybrid populations derived from the F₃ and F₄ generations is presented. The trisomics were scored for several morphologically differentiating characters and most of them were intermediate between the parental species, a few resembling the olitorius parent more. Cytological studies showed the formation of abnormal sporads in trisomics with different frequencies indicating a misdivision at meiosis. This imbalance at meiosis results in a higher percentage of pollen sterility in the trisomics as compared with the parents. Analysis of M₁ of meiosis showed that there were: differences in the frequencies of the various chromosome configurations between the two categories of trisomics; significantly higher trivalent frequencies per PMC in the green trisomics; in contrast significantly hihger univalent frequencies per PMC in the red trisomics. No significant difference in chiasma formation was observed between red and green trisomics, nor between trisomics and their parental species. It appears that segmental homology in the parental chromosomes has probably resulted in varying degrees of preferential pairing in the trisomic hybrid.     

Cytology of inbreds and f 1 hybrids of pearl millet

Summary The meiotic behaviour of chromosomes was studied in four inbred lines and their F ₁ hybrids of P. typhoides. The inbred lines showed a decrease in mean chiasma frequency when compared with the population plants, but differed from one another in their mean chiasma frequencies. Together with the decrease in mean chiasma frequency the inbreds showed variation in mean chiasma frequencies. The inbred lines showed a number of meiotic abnormalities such as extra chromosomes, extra fragments, desynapsis, persistent nucleoli and differential condensation of chromosomes. The F ₁ hybrids of these inbreds exhibited heterosis for chiasma frequency. All the F ₁'s had mean chiasma frequencies higher than the means of the respective participating parents. The F ₁'s, however, differed in the degree of heterosis exhibited. In the F ₁ hybrids, the variation in mean chiasma frequency, both between plants and between PMC's within plants, was significantly lower than that of the inbred lines. The effect of environment was studied in the inbred lines and their F ₁ hybrids. The mean chiasma frequencies of the inbred lines were significantly lower, and the variation in mean chiasma frequencies was greater, in the stress season. The mean chiasma frequencies of F ₁'s did not show any significant differences between the two seasons. The F ₁'s exhibited less variation in mean chiasma frequency than the inbred lines, showing that F ₁'s were developmentally more stable. The F ₁'s did not show any meiotic abnormalities in either season.     

Basal level of human platelet prostaglandins: PGE1 is more elevated than PGE2

Radioimmunoassays of platelet prostaglandins E₁ and F_1α in platelet rich plasma or platelet suspension, demonstrate that both PGE₁ and PGF_1α are present at higher concentrations than prostaglandins E₂ and F_2α. Gas chromatography — mass spectrometry determinations of prostaglandins E₁ and E₂ in resting washed platelets confirm this difference. Lastly, there is a greater incorporation of [1-¹⁴C] acetate into prostaglandins E₁ and F_1α compared to that into prostaglandins E₂ and F_2α.     

Centromere Orientation of Quadrivalents of Heterozygous Translocations and an Autoploid of GOSSYPIUM HIRSUTUM L

Cytological observations of quadrivalents of heterozygous translocations in Gossypium hirsutum L. demonstrate that, in addition to alternate-1 and alternate-2 orientations, a third alternate orientation (alternate-3), which occurs as a three-dimensional, V-type configuration, can be identified.—Two additional types of disjunctions, the centromere orientations of which are rotational modifications of either adjacent or alternate configurations, were also observed in quadrivalents of a translocation heterozygote. These two types are rare, and both appear in the form of the Roman numeral X . The X and the alternate-3 types also occur in quadrivalents of an autoploid of G. hirsutum.—The two X types, along with adjacent-1, adjacent-2, alternate-1 and alternate-2 orientations, represent the six possible types of planar 2 x 2 random orientation of the four centromeres of a quadrivalent. Including the three-dimensional alternate-3 type, there are seven types of orientation.     

The genetic map of the mitochondrial genome in yeast

Summary An approach for the screening of mit ^- mutants, the isolation and preliminary classification of a series of such mutants is reported. Loss and retention of 8 mit ^- and 6 drug ^r markers in mitDNA was analyzed in populations of rho^- clones derived from four yeast strains. The populations studied constitute a representative fraction of the rho^- petites formed during growth at 35° C under the influence of mutation tsp-25 which is in common to the four strains. The majority of the rho^- clones retained several of the markers studied. Depending on the marker regarded retention frequencies between 15% (oxi3) and 45% (oli1, cob) were observed. Loss of one and retention of the other of a pair of markers was determined in all rho^- clones of the four populations. The frequencies of marker separation by rho^- deletion thus obtained are assumed to reflect the distance between markers on the mitochondrial genome: the higher the frequency of separation the longer the distance between two markers. Based on these frequencies a unique order of markers on a circular map was determined. Positions of markers on a scale from 0 to 100 were found to be: cap/ery (0) — olil (16) — cob1-1354 (21) — ana101 (22) — cob2-1625 (24) — oli2 (35) — pho1 (40) — oxi3-2501 (44) — oxi3-3771 (47) — par (65) — oxi2 (79) — oxil (87) tms8 (93) —cap (100). The relevance of this map as to the faithful representation of the topology of gene loci on mitDNA is discussed. Correlation of retention frequencies of markers to their map positions reveals a pronounced polarity: mitDNA segments carrying the cob-oli1 segment prevail whereas segments retaining oxi3 are the least frequent.