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Margaret Sedgley

Bio: Margaret Sedgley is an academic researcher from University of New England (Australia). The author has contributed to research in topics: Pollen & Pollen tube. The author has an hindex of 37, co-authored 152 publications receiving 3929 citations. Previous affiliations of Margaret Sedgley include University of Adelaide & University of New England (United States).
Topics: Pollen, Pollen tube, Pollination, Pruning, Shoot


Papers
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Journal ArticleDOI
TL;DR: The effect of the environment, interactions with vegetative growth, the roles of plant growth regulators and carbohydrates, and recent advances in molecular biology, are discussed.
Abstract: The intention of this review is to discuss floral initiation of horticultural trees. Floral initiation is best understood for herbaceous species, especially at the molecular level, so a brief overview of the control of floral initiation of Arabidopsis (Arabidopsis thaliana (L.) Heynh.) precedes the discussion of trees. Four major pathways to flowering have been characterized in Arabidopsis, including environmental induction through photoperiod and temperature, autonomous floral initiation, and regulation by gibberellins. Tropical trees are generally induced to flower through environmental cues, whereas floral initiation of temperate deciduous trees is often autonomous. In the tropical evergreen tree mango, Mangifera indica L., cool temperature is the only factor known to induce flowering, but does not ensure floral initiation will occur because there are important interactions with vegetative growth. The temperate deciduous tree apple, Malus domestica Borkh., flowers autonomously, with floral initiation dependent on aspects of vegetative development in the growing season before anthesis, although with respect to the floral initiation of trees in general: the effect of the environment, interactions with vegetative growth, the roles of plant growth regulators and carbohydrates, and recent advances in molecular biology, are discussed.

299 citations

Journal ArticleDOI
TL;DR: High resolution melting curve analysis was applied to almond SNP discovery and genotyping based on the predicted SNP information derived from the almond and peach EST database to demonstrate its ability to detect variation as small as one base difference between samples.
Abstract: High resolution melting curve (HRM) is a recent advance for the detection of SNPs. The technique measures temperature induced strand separation of short PCR amplicons, and is able to detect variation as small as one base difference between samples. It has been applied to the analysis and scan of mutations in the genes causing human diseases. In plant species, the use of this approach is limited. We applied HRM analysis to almond SNP discovery and genotyping based on the predicted SNP information derived from the almond and peach EST database. Putative SNPs were screened from almond and peach EST contigs by HRM analysis against 25 almond cultivars. All 4 classes of SNPs, INDELs and microsatellites were discriminated, and the HRM profiles of 17 amplicons were established. The PCR amplicons containing single, double and multiple SNPs produced distinctive HRM profiles. Additionally, different genotypes of INDEL and microsatellite variations were also characterised by HRM analysis. By sequencing the PCR products, 100 SNPs were validated/revealed in the HRM amplicons and their flanking regions. The results showed that the average frequency of SNPs was 1:114 bp in the genic regions, and transition to transversion ratio was 1.16:1. Rare allele frequencies of the SNPs varied from 0.02 to 0.5, and the polymorphic information contents of the SNPs were from 0.04 to 0.53 at an average of 0.31. HRM has been demonstrated to be a fast, low cost, and efficient approach for SNP discovery and genotyping, in particular, for species without much genomic information such as almond.

155 citations

Journal ArticleDOI
TL;DR: This paper describes rapid and efficient DNA extraction methods for mature leaves, resting buds and seedling leaves of genera in the family Proteaceae using previously published techniques.
Abstract: This paper describes rapid and efficient DNA extraction methods for mature leaves, resting buds and seedling leaves of genera in the family Proteaceae. The procedures combine and modify previously published techniques. The DNA can be digested by restriction endonucleases and is suitable for subsequent PCR amplification.

102 citations

Journal ArticleDOI
TL;DR: Leaves of 22 accessions of olive from three named cultivars, and 17 accessions from cultivars with names that are suspected to include synonyms, showed a within-cultivar genetic similarity of at least 98% irrespective of source, while Verdale showed a high genetic variability, with some accessions having less than 80% similarity to others.
Abstract: SummaryLeaves of 22 accessions of olive (Olea europaea L.) from three named cultivars (Manzanillo, Kalamata, and Verdale), and 17 accessions from cultivars with names that are suspected to include synonyms (Corregiola, Corregiolo, Frantoio, Frantoja, Frantojol, Nevadillo, Nevadillo Blanco, and Picual) were obtained from Israel, Italy, the USA and Australia. Their genetic variability was investigated using random amplified polymorphic DNA (RAPD). Analysis of the PCR products was achieved by using the simple matching coefficient and UPGMA clustering. `Manzanillo' and `Kalamata' showed a within-cultivar genetic similarity of at least 98% irrespective of source. In contrast, `Verdale' showed a high genetic variability, with some accessions having less than 80% similarity to others. `Picual' and `Nevadillo' (including `Nevadillo Blanco'), which clustered at 69%, are possibly distinct cultivars. The identity of `Corregiola' and `Frantoio' and their synonyms is uncertain. Considering the extent of the genetic di...

95 citations

Journal ArticleDOI
01 Jan 2004-Genome
TL;DR: An integrated molecular linkage map of olive was constructed based on randomly amplified polymorphic DNA (RAPD), sequence characterized amplified region (SCAR), and microsatellite markers using the pseudo-testcross strategy to be the starting point for studies on the structure, evolution, and function of the olive genome.
Abstract: An integrated molecular linkage map of olive (Olea europaea L.) was constructed based on randomly amplified polymorphic DNA (RAPD), sequence characterized amplified region (SCAR), and microsatellit...

94 citations


Cited by
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Journal ArticleDOI
TL;DR: In apoptosis, selective activation of an endogenous endonuclease appears to be responsible not only for widespread chromatin cleavage but also for the major nuclear morphologic changes, including conservation of the nucleolin-rich fibrillar center.
Abstract: The developmental types of secretory cavities in Citrus remain unclear and whether or not programmed cell death is involved in the developmental process of secretory cavities remains an enigma. Regarding cavity formation in Citrus sinensis fruits, this work uncovered novel evidence to delineate secretory cavity formation in schizolysigeny, supporting the possibility of utilizing secretory cavities as a new cell biology model for investigating the molecular mechanism of plant programmed cell death.

1,741 citations

Journal ArticleDOI
TL;DR: The results achieved so far indicate that various plant organs, in a definite hierarchy and in interaction with each other, are involved in determining crop yield under stress.
Abstract: As the result of intensive research and breeding efforts over the last 20 years, the yield potential and yield quality of cereals have been greatly improved. Nowadays, yield safety has gained more importance because of the forecasted climatic changes. Drought and high temperature are especially considered as key stress factors with high potential impact on crop yield. Yield safety can only be improved if future breeding attempts will be based on the valuable new knowledge acquired on the processes determining plant development and its responses to stress. Plant stress responses are very complex. Interactions between plant structure, function and the environment need to be investigated at various phases of plant development at the organismal, cellular as well as molecular levels in order to obtain a full picture. The results achieved so far in this field indicate that various plant organs, in a definite hierarchy and in interaction with each other, are involved in determining crop yield under stress. Here we attempt to summarize the currently available information on cereal reproduction under drought and heat stress and to give an outlook towards potential strategies to improve yield safety in cereals.

1,547 citations

Journal ArticleDOI
TL;DR: Internal Organization of the Plant Body, from embryo to the Adult Plant, and some Factors in Development of Secondary Xylem: Common Types of Secondary Growth.
Abstract: INTRODUCTION. Internal Organization of the Plant Body. Summary of Types of Cells and Tissues. General References. DEVELOPMENT OF THE SEED PLANT. The Embryo. From embryo to the Adult Plant. Apical Meristems and Their Derivatives. Differentiation, Specialization, and Morphogenesis. References. THE CELL. Cytoplasm. Nucleus. Plastids. Mitochondria. Microbodies. Vacuoles. Paramural Bodies. Ribosomes. Dictyosomes. Endoplasmic Reticulum. Lipid Globules. Microtubules. Ergastic Substances. References. CELL WALL. Macromolecular Components and Their Organization in the Wall. Cell Wall Layers. Intercellular Spaces. Pits, Primary Pit--Fields, and Plasmodesmata. Origin of Cell Wall During Cell Division. Growth of Cell Wall. References. PARENCHYMA AND COLLENCHYMA. Parenchyma. Collenchyma. References. SCLERENCHYMA. Sclereids. Fibers. Development of Sclereids and Fibers. References. EPIDERMIS. Composition. Developmental Aspects. Cell Wall. Stomata. Trichomes. References. XYLEM: GENERAL STRUCTURE AND CELL TYPES. Gross Structure of Secondary Xylem. Cell Types in the Secondary Xylem. Primary Xylem. Differentiation of Tracheary Elements. References. XYLEM: VARIATION IN WOOD STRUCTURE. Conifer Wood. Dicotyledon Wood. Some Factors in Development of Secondary Xylem. Identification of Wood. References. VASCULAR CAMBIUM. Organization of Cambium. Developmental Changes in the Initial Layer. Patterns and Causal Relations in Cambial Activity. References. PHLOEM. Cell Types. Primary Phloem. Secondary Phloem. References. PERIDERM. Structure of Periderm and Related Tissues. Development of Periderm. Outer Aspect of Bark in Relation to Structure. Lenticels. References. SECRETORY STRUCTURES. External Secretory Structures. Internal Secretory Structures. References. THE ROOT: PRIMARY STATE OF GROWTH. Types of Roots. Primary Structure. Development. References. THE ROOT: SECONDARY STATE OF GROWTH AND ADVENTITIOUS ROOTS. Common Types of Secondary Growth. Variations in Secondary Growths. Physiologic Aspects of Secondary Growth in Roots. Adventitious Roots. References. THE STEM: PRIMARY STATE OF GROWTH. External Morphology. Primary Structure. Development. References. THE STEM: SECONDARY GROWTH AND STRUCTURAL TYPES. Secondary Growth. Types of Stems. References. THE LEAF: BASIC STRUCTURE AND DEVELOPMENT. Morphology. Histology of Angiosperm Leaf. Development. Abscission. References. THE LEAF: VARIATIONS IN STRUCTURE. Leaf Structure and Environment. Dicotyledon Leaves. Monocotyledon Leaves. Gymnosperm Leaves. References. THE FLOWER: STRUCTURE AND DEVELOPMENT. Concept. Structure. Development. References. THE FLOWER: REPRODUCTIVE CYCLE. Microsporogenesis. Pollen. Male Gametophyte. Megasporogenesis. Female Gametophyte. Fertilization. References. THE FRUIT. Concept and Classification. The Fruit Wall. Fruit Types. Fruit Growths. Fruit Abscission. References. THE SEED. Concept and Morphology. Seed Development. Seed Coat. Nutrient Storage Tissues. References. EMBRYO AND SEEDLING. Mature Embryo. Development of Embryo. Classification of Embryos. Seedling. References. Glossary. Index.

1,454 citations

Journal ArticleDOI
TL;DR: The impacts of climate variability for crop production in a number of crops are demonstrated and it is argued that characters that enable better exploration of the soil and slower leaf canopy expansion could lead to crop higher transpiration efficiency.
Abstract: The yield and quality of food crops is central to the well being of humans and is directly affected by climate and weather. Initial studies of climate change on crops focussed on effects of increased carbon dioxide (CO2) level and/or global mean temperature and/or rainfall and nutrition on crop production. However, crops can respond nonlinearly to changes in their growing conditions, exhibit threshold responses and are subject to combinations of stress factors that affect their growth, development and yield. Thus, climate variability and changes in the frequency of extreme events are important for yield, its stability and quality. In this context, threshold temperatures for crop processes are found not to differ greatly for different crops and are important to define for the major food crops, to assist climate modellers predict the occurrence of crop critical temperatures and their temporal resolution. This paper demonstrates the impacts of climate variability for crop production in a number of crops. Increasing temperature and precipitation variability increases the risks to yield, as shown via computer simulation and experimental studies. The issue of food quality has not been given sufficient importance when assessing the impact of climate change for food and this is addressed. Using simulation models of wheat, the concentration of grain protein is shown to respond to changes in the mean and variability of temperature and precipitation events. The paper concludes with discussion of adaptation possibilities for crops in response to drought and argues that characters that enable better exploration of the soil and slower leaf canopy expansion could lead to crop higher transpiration efficiency.

908 citations

Journal ArticleDOI
TL;DR: The results suggest that RAPD can be a sensitive method for detection of genetic structuring according to the isolation-by-distance model, but also means that sampling strategies, as applied in individual studies, can seriously influence the resulting estimates of between-population diversity.
Abstract: A compilation of studies using RAPD markers for evaluating population differentiation resulted in 78 estimates of AMOVA-derived Φ ST and 31 estimates of Nei's G ST , as well as in 41 estimates of Nei's within-population diversity. In outcrossing taxa, estimates of between-population diversity were closely correlated with maximum geographic distance between sampled populations. A corresponding association was not found in selfing taxa. These results suggest that RAPD can be a sensitive method for detection of genetic structuring according to the isolation-by-distance model. However, it also means that sampling strategies, as applied in individual studies, can seriously influence the resulting estimates of between-population diversity. Other sampling strategies, like number of plants per population and number of scored polymorphic markers, do not seem to impart any serious artefacts. As previously verified with allozyme data, RAPD markers showed that long-lived, outcrossing, late successional taxa retain most of their genetic variability within populations. By contrast, annual, selfing and/or early successional taxa allocate most of the genetic variability among populations. Estimates for between- and within-population diversity, respectively, proved to be negatively correlated, as previously reported for allozyme data. The only major discrepancy between allozymes and RAPD markers concerns geographic range; within-population diversity was strongly affected by distributional range of the investigated species in the allozyme data but not in the RAPD data. Moreover, RAPD-based values for between-population diversity increased with increasing distributional range whereas the opposite has been reported in a large allozyme data compilation. Contrary to allozymes, RAPD marker-derived within-population diversity is probably therefore not a very good predictor of total species genetic diversity.

832 citations