scholarly journals Genetic Dissection of Apomixis in Dandelions Identifies a Dominant Parthenogenesis Locus and Highlights the Complexity of Autonomous Endosperm Formation

Genes ◽  
2020 ◽  
Vol 11 (9) ◽  
pp. 961 ◽  
Author(s):  
Peter J. Van Dijk ◽  
Rik Op den Camp ◽  
Stephen E. Schauer
Keyword(s):  
Genetic Basis ◽  
Endosperm Development ◽  
Dominant Factor ◽  
Genetic Dissection ◽  
Marker Allele ◽  
Nomarski Differential Interference Contrast ◽  
Autonomous Endosperm ◽  
Endosperm Formation ◽  
Common Dandelion ◽  
The Individual

Apomixis in the common dandelion (Taraxacum officinale) consists of three developmental components: diplospory (apomeiosis), parthenogenesis, and autonomous endosperm development. The genetic basis of diplospory, which is inherited as a single dominant factor, has been previously elucidated. To uncover the genetic basis of the remaining components, a cross between a diploid sexual seed parent and a triploid apomictic pollen donor was made. The resulting 95 triploid progeny plants were genotyped with co-dominant simple-sequence repeat (SSR) markers and phenotyped for apomixis as a whole and for the individual apomixis components using Nomarski Differential Interference Contrast (DIC) microscopy of cleared ovules and seed flow cytometry. From this, a new SSR marker allele was discovered that was closely linked to parthenogenesis and unlinked to diplospory. The segregation of apomixis as a whole does not differ significantly from a three-locus model, with diplospory and parthenogenesis segregating as unlinked dominant loci. Autonomous endosperm is regularly present without parthenogenesis, suggesting that the parthenogenesis locus does not also control endosperm formation. However, the high recovery of autonomous endosperm is inconsistent with this phenotype segregating as the third dominant locus. These results highlight the genetic complexity underlying apomixis in the dandelion and underline the challenge of introducing autonomous apomixis into sexual crops.

scholarly journals The Rab Geranylgeranyl Transferase Beta Subunit Is Essential for Embryo and Seed Development in Arabidopsis thaliana

2021 ◽  
Vol 22 (15) ◽  
pp. 7907
Author(s):  
Joanna Rojek ◽  
Matthew R. Tucker ◽  
Michał Rychłowski ◽  
Julita Nowakowska ◽  
Małgorzata Gutkowska
Keyword(s):  
Seed Development ◽  
Auxin Transport ◽  
Rab Proteins ◽  
Vesicular Traffic ◽  
Polar Localization ◽  
Reproductive Structures ◽  
Autonomous Endosperm ◽  
Endosperm Formation ◽  
Geranylgeranyl Transferase ◽  
Unfertilized Ovules

Auxin is a key regulator of plant development affecting the formation and maturation of reproductive structures. The apoplastic route of auxin transport engages influx and efflux facilitators from the PIN, AUX and ABCB families. The polar localization of these proteins and constant recycling from the plasma membrane to endosomes is dependent on Rab-mediated vesicular traffic. Rab proteins are anchored to membranes via posttranslational addition of two geranylgeranyl moieties by the Rab Geranylgeranyl Transferase enzyme (RGT), which consists of RGTA, RGTB and REP subunits. Here, we present data showing that seed development in the rgtb1 mutant, with decreased vesicular transport capacity, is disturbed. Both pre- and post-fertilization events are affected, leading to a decrease in seed yield. Pollen tube recognition at the stigma and its guidance to the micropyle is compromised and the seed coat forms incorrectly. Excess auxin in the sporophytic tissues of the ovule in the rgtb1 plants leads to an increased tendency of autonomous endosperm formation in unfertilized ovules and influences embryo development in a maternal sporophytic manner. The results show the importance of vesicular traffic for sexual reproduction in flowering plants, and highlight RGTB1 as a key component of sporophytic-filial signaling.

IMMUNOLOGIC AND BIOCHEMICAL STUDIES IN INFANTS AND CHILDREN WITH SPECIAL REFERENCE TO RHEUMATIC FEVER

PEDIATRICS ◽  
1948 ◽  
Vol 2 (5) ◽  
pp. 570-576
Author(s):  
ROSE LUBSCHEZ
Keyword(s):  
Rheumatic Fever ◽  
Genetic Basis ◽  
Gamma Globulin ◽  
Relative Concentration ◽  
Electrophoretic Pattern ◽  
Normal Children ◽  
Beta Globulin ◽  
Biochemical Studies ◽  
The Individual ◽  
In Infants And Children

Electrophoretic analyses of blood plasma or serum of 30 children in apparent health between the ages of two and 11 years revealed that the relative concentration of the various components was in close agreement with adult values, although the individual variation was several times greater. For 27 children in apparent health, but who had experienced various types of infection during a one to four month interval prior to the time the specimen was taken, elevation of the gamma component occurred in about 40% of the determinations. Illness within the month produced the greatest number of abnormalities, although abnormalities were noted in specimens of children who had been free of infection two to three months. A few abnormalities were noted in all components except beta globulin. At younger ages (two to four years) children showed a slightly higher albumen level and a slightly lower gamma globulin level. Normal children susceptible to rheumatic fever on a genetic basis exhibited no specific differences in the electrophoretic pattern.

INVESTIGATION OF HORMETIC STIMULATION IN STRAWBERRY PLANTS USING IONIZING RADIATION

1987 ◽  
Vol 67 (4) ◽  
pp. 1181-1192 ◽  
Author(s):  
S. C. SHEPPARD ◽  
C. L. GIBB ◽  
J. L. HAWKINS ◽  
W. R. REMPHREY
Keyword(s):  
Ionizing Radiation ◽  
Field Trials ◽  
Early Growth ◽  
Dominant Factor ◽  
X Rays ◽  
X Ray ◽  
Significant Stimulation ◽  
Low Levels ◽  
The Individual ◽  
Stimulation Of

Hormesis is the stimulation of growth by very low levels of inhibitors or stressors. This phenomenon may be useful in crops where the usual cultural factors have been optimized. The literature indicates that substantial stimulation of early growth of strawberries (Fragaria × ananassa) could be achieved by exposing transplants to low doses of ionizing radiation. Experiments were conducted to test the effectiveness and reliability of X rays as a hormetic agent. Plants of a day-neutral cultivar Hecker and of a June-bearing cultivar Glooscap were irradiated at 0.5–16 Gy and planted in pots. The plants were grown outdoors and growth was recorded each week. Significant stimulation above the controls in the number of trifoliate leaves occurred in the day-neutral cultivar. This effect persisted until the first phase of fruiting. No significant stimulatory effects were observed at any time in the June-bearing cultivar. Two field trials with a June-bearing cultivar Redcoat, irradiated at doses of 0.5 and 2 Gy, also revealed no significant stimulation. The dominant factor regulating early growth was the size of the individual transplants. Therefore, although hormetic stimulation may occur, it will be difficult to quantify and optimize and it will not likely be useful for practical application.Key words: X ray, transplant, day-neutral, June-bearing

Genetic Dissection of Haploid Male Fertility in Maize (Zea mays L.)

2018 ◽  
Author(s):  
Jiwei Yang ◽  
Haochuan Li ◽  
Yanzhi Qu ◽  
Qiong Chen ◽  
Jihua Tang ◽  
...  
Keyword(s):  
Male Fertility ◽  
Genetic Basis ◽  
Mapping Population ◽  
Transgressive Segregation ◽  
Haploid Genome ◽  
Genetic Dissection ◽  
Genome Doubling ◽  
Haploid Male ◽  
Female Donor ◽  
Simple Sequence

AbstractHaploid genome doubling is a key limiting step of haploid breeding in maize. Spontaneous restoration of haploid male fertility (HMF) provides a method by which costs can be saved and which does not require the use of toxic chemicals, in contrast to the artificial doubling process. To reveal the genetic basis of HMF, haploids were obtained from the offspring of 285 F2:3 families, derived from the cross Zheng58× K22. The F2:3 families were used as female donor and YHI-1 as the male inducer line. The rates of HMF from each family line were evaluated at two field sites over two planting seasons. Quantitative trait loci (QTL) for HMF were identified using a genetic linkage map containing 157 simple sequence repeat (SSR) markers. QTL for HMF displayed incomplete dominance. Transgressive segregation of haploids from F2:3 families was observed relative to haploids derived from the two parents of the mapping population. A total of nine QTL were detected, which were distributed on chromosomes 1, 3, 4, 7, and 8. Three QTL, qHMF3b, qHMF7a, and qHMF7b were detected in both locations, respectively. In our mapping population, HMF was controlled by three major QTL. These QTL could be useful to predict the ability of spontaneous haploid genome doubling in related breeding materials, and to accelerate the haploid breeding process by introgression or aggregation of those QTL.

THE RELATIONSHIP BETWEEN ENDOSPERM DEVELOPMENT AND MORPHOLOGIC CHARACTERS IN THE F2 GENERATION OF A T. DICOCCUM × T. VULGARE CROSS

1931 ◽  
Vol 5 (2) ◽  
pp. 208-218 ◽  
Author(s):  
J. B. Harrington
Keyword(s):  
Random Sample ◽  
Large Population ◽  
Morphological Characters ◽  
Endosperm Development ◽  
Class A ◽  
Class B ◽  
Class C ◽  
F2 Generation ◽  
The Individual ◽  
The Relationship

The relationship between the degree of plumpness of F2 seeds and the type of the resulting F2 plants was studied in the cross Vernal (T. dicoccum) × Marquis (T. vulgare). A random sample of F2 seeds was divided into three classes based upon kernel plumpness, viz. plump (Class A), slightly shrunken (Class B), and shrunken (Class C). In these there were by number 55.5, 41.0 and 3.5% of seeds respectively. Emergence of F2 plants in the field was 64, 58 and 36% for Classes A, B and C. The F2 plants were studied for 13 morphological characters. Comparing the populations for all characters combined, Class A was more dicoccum-like than Class B, and Class B much more dicoccum-like than Class C. The proportion of vulgare-like character was 16, 20 and 32% for Classes A, B and C, respectively. Considering the character of the individual plants, the ratios of dicoccum-like to vulgare-like were 12.1:1, 5.3:1, and 2.2:1 for classes A, B and C, respectively. Furthermore, the vulgare-like plants of classes A and B were less vulgare-like than those of Class C. There were present, however, in Classes A and B some plants that were fully as vulgare-like as any in Class C. These results indicate that, in an interspecific wheat cross, the breeder should give special attention to the shrunken F2 seeds if he has very limited nursery space and a large amount of seed; whereas if he has plenty of space for a large population, special care of shrunken F2 seeds does not seem warranted.

scholarly journals The genomes of a monogenic fly: views of primitive sex chromosomes

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Anne A. Andere ◽  
Meaghan L. Pimsler ◽  
Aaron M. Tarone ◽  
Christine J. Picard
Keyword(s):  
Sex Chromosomes ◽  
Genomic Analysis ◽  
Female Offspring ◽  
Dominant Factor ◽  
Blow Fly ◽  
Chrysomya Rufifacies ◽  
Specific Expression ◽  
Male And Female ◽  
Single Sex ◽  
The Individual

Abstract The production of male and female offspring is often determined by the presence of specific sex chromosomes which control sex-specific expression, and sex chromosomes evolve through reduced recombination and specialized gene content. Here we present the genomes of Chrysomya rufifacies, a monogenic blow fly (females produce female or male offspring, exclusively) by separately sequencing and assembling each type of female and the male. The genomes (> 25X coverage) do not appear to have any sex-linked Muller F elements (typical for many Diptera) and exhibit little differentiation between groups supporting the morphological assessments of C. rufifacies homomorphic chromosomes. Males in this species are associated with a unimodal coverage distribution while females exhibit bimodal coverage distributions, suggesting a potential difference in genomic architecture. The presence of the individual-sex draft genomes herein provides new clues regarding the origination and evolution of the diverse sex-determining mechanisms observed within Diptera. Additional genomic analysis of sex chromosomes and sex-determining genes of other blow flies will allow a refined evolutionary understanding of how flies with a typical X/Y heterogametic amphogeny (male and female offspring in similar ratios) sex determination systems evolved into one with a dominant factor that results in single sex progeny in a chromosomally monomorphic system.

scholarly journals Genetic dissection of yield-related traits and mid-parent heterosis for those traits in maize (Zea mays L.)

2019 ◽  
Vol 19 (1) ◽  
Author(s):  
Qiang Yi ◽  
Yinghong Liu ◽  
Xianbin Hou ◽  
Xiangge Zhang ◽  
Hui Li ◽  
...  
Keyword(s):  
Genetic Basis ◽  
Recombinant Inbred Lines ◽  
Kernel Weight ◽  
Genetic Dissection ◽  
Hybrid Mapping ◽  
Maize Breeding ◽  
Phenotypic Variations ◽  
Selection For ◽  
Genomic Regions ◽  
Mapping Populations

Abstract Background Utilization of heterosis in maize could be critical in maize breeding for boosting grain yield. However, the genetic architecture of heterosis is not fully understood. To dissect the genetic basis of yield-related traits and heterosis in maize, 301 recombinant inbred lines derived from 08 to 641 × YE478 and 298 hybrids from the immortalized F2 (IF2) population were used to map quantitative trait loci (QTLs) for nine yield-related traits and mid-parent heterosis. Results We observed 156 QTLs, 28 pairs of loci with epistatic interaction, and 10 significant QTL × environment interactions in the inbred and hybrid mapping populations. The high heterosis in F1 and IF2 populations for kernel weight per ear (KWPE), ear weight per ear (EWPE), and kernel number per row (KNPR) matched the high percentages of QTLs (over 50%) for those traits exhibiting overdominance, whereas a notable predominance of loci with dominance effects (more than 70%) was observed for traits that show low heterosis such as cob weight per ear (CWPE), rate of kernel production (RKP), ear length (EL), ear diameter (ED), cob diameter, and row number (RN). The environmentally stable QTL qRKP3–2 was identified across two mapping populations, while qKWPE9, affecting the trait mean and the mid-parent heterosis (MPH) level, explained over 18% of phenotypic variations. Nine QTLs, qEWPE9–1, qEWPE10–1, qCWPE6, qEL8, qED2–2, qRN10–1, qKWPE9, qKWPE10–1, and qRKP4–3, accounted for over 10% of phenotypic variation. In addition, QTL mapping identified 95 QTLs that were gathered together and integrated into 33 QTL clusters on 10 chromosomes. Conclusions The results revealed that (1) the inheritance of yield-related traits and MPH in the heterotic pattern improved Reid (PA) × Tem-tropic I (PB) is trait-dependent; (2) a large proportion of loci showed dominance effects, whereas overdominance also contributed to MPH for KNPR, EWPE, and KWPE; (3) marker-assisted selection for markers at genomic regions 1.09–1.11, 2.04, 3.08–3.09, and 10.04–10.05 contributed to hybrid performance per se and heterosis and were repeatedly reported in previous studies using different heterotic patterns is recommended.

Relation between baroreflex sensitivity and cardiac vagal tone in humans

1994 ◽  
Vol 266 (1) ◽  
pp. H21-H27 ◽  
Author(s):  
M. Kollai ◽  
G. Jokkel ◽  
I. Bonyhay ◽  
J. Tomcsanyi ◽  
A. Naszlady
Keyword(s):  
Baroreflex Sensitivity ◽  
Regression Line ◽  
Systolic Pressure ◽  
Vagal Tone ◽  
Threshold Level ◽  
Dominant Factor ◽  
Cardiac Vagal Tone ◽  
The Individual ◽  
Method R ◽  
Maximum Threshold

The extent of dependence of cardiac vagal tone on arterial baroreceptor input has been studied in 12 healthy, young adult subjects. Cardiac vagal tone was defined as the chang in R-R interval after complete cholinergic blockade by atropine. Baroreflex sensitivity was determined with the "Oxford-method": R-R interval was regressed against systolic pressure. The interindividual correlation between cardiac vagal tone and baroreflex sensitivity for falling pressures was found to be significant, but not close (R = 0.81, P = 0.002). In each subject, the baroreflex regression line for falling pressures was extrapolated to the post-atropine R-R interval level; 50 mmHg was considered as minimum and 80 mmHg as maximum threshold level for the integrated baroreflex. From the relation between the individual regression lines and the minimum and maximum threshold levels, it was concluded that cardiac vagal tone could be generated by both baroreflex-dependent and -independent mechanisms, the ratio of which varies in different individuals, with the baroreflex-dependent mechanism being the dominant factor.

An ultrastructural study of embryo and endosperm development during in vitro culture of maize ovaries (Zea mays)

1986 ◽  
Vol 64 (10) ◽  
pp. 2227-2238 ◽  
Author(s):  
J. H. N. Schel ◽  
H. Kieft
Keyword(s):  
In Vitro Culture ◽  
Embryo Development ◽  
Light And Electron Microscopy ◽  
Culture Method ◽  
Endosperm Development ◽  
Endosperm Formation ◽  
Development In Vitro ◽  
Maize Embryos

A culture method is described which allows the continuous supply of fresh liquid medium and which prevents the accumulation of toxic metabolites. Development of maize embryos and endosperm after various periods of in vitro ovary culture was studied by light and electron microscopy. Using this method the ultrastructural features of embryo development in vitro were similar to those of in vivo embryos. In contrast, the formation of endosperm was irregular with the absence of cellularization of the inner endosperm being frequent. In some cases, only the endosperm developed without any indication of embryo formation. In a calcium-depleted medium, embryo development was normal but again, endosperm formation was aberrant. No cells were formed in the central part of the endosperm and near the placental region degeneration took place, resulting in vacuoles with dark inclusions, clumps of rough endoplasmic reticulum membranes, and cellular breakdown. The events occurring after in vitro culture strongly resemble those taking place after intergeneric crosses or crosses between diploid and tetraploid strains. It is concluded that defective endosperm development is probably the main factor for the failure of embryo development.

Ovule, embryo sac, embryo, and endosperm development in leafy spurge (Euphorbia esula)

1999 ◽  
Vol 77 (4) ◽  
pp. 599-610 ◽  
Author(s):  
Jeffrey S Carmichael ◽  
Sarena M Selbo
Keyword(s):  
Embryo Sac ◽  
Placental Tissue ◽  
Leafy Spurge ◽  
Endosperm Development ◽  
Protein Bodies ◽  
Euphorbia Esula ◽  
Invasive Weed ◽  
Polygonum Type ◽  
Nutrient Reserve ◽  
Endosperm Formation

Leafy spurge (Euphorbia esula L.) is a noxious, invasive weed that dominates many agriculturally important regions. While many research efforts are currently aimed at controlling the spread of this plant, relatively little is known about its sexual reproductive biology, especially from a structural perspective. This report describes key features of ovule development, embryogenesis, and endosperm formation in leafy spurge. Ovules are anatropous, bitegmic, and form a zigzag micropyle. A distinct elaisome (caruncle) and hypostase are formed as ovules mature. Obturators are present and are derived from placental tissue. The embryo sac conforms to the Polygonum type. A single embryo is formed in each seed and stores nutrients primarily as globoid protein bodies. Endosperm is persistent and also contains protein bodies as its primary nutrient reserve. Preliminary structural evidence is presented that indicates the potential for apomixis.Key words: leafy spurge, Euphorbiaceae, Euphorbia, ovule, endosperm, embryo.

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