TL;DR: In this paper, the authors describe the development of a seed from embryo to the adult plant, including the growth of the cell wall and the root growth in the secondary growth stages of the seed.
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.
TL;DR: Ag(I), applied foliarly as AgNO(3), effectively blocked the ability of exogenously applied ethylene to elicit the classical "triple" response in intact etiolated peas and should prove useful in defining further the role of ethylene in plant growth.
Abstract: Ag(I), applied foliarly as AgNO3, effectively blocked the ability of exogenously applied ethylene to elicit the classical “triple” response in intact etiolated peas (Pisum sativumcv. Alaska); stimulate leaf, flower, and fruit abscission in cotton (Gossypium hirsutumcv. Stoneville 213); and induce senescence of orchids (Hybrid white Cattleya, Louise Georgeianna). This property of Ag(I) surpasses that of the well known ethylene antagonist, CO2, and its persistence, specificity, and lack of phytotoxicity at effective concentrations should prove useful in defining further the role of ethylene in plant growth.
TL;DR: The rate-limiting step of cytokinin biosynthesis in Arabidopsis thaliana Heynh is catalyzed by ATP/ADP isopentenyltransferases, and by their homologs AtIPT3, atIPT5, AtipT6, At IPT7, and AtIPt8, and they were expressed ubiquitously, with highest expression in proliferating tissues.
Abstract: The rate-limiting step of cytokinin biosynthesis in Arabidopsis thaliana Heynh. is catalyzed by ATP/ADP isopentenyltransferases, A. thaliana IsoPentenyl Transferase (AtIPT)1, and AtIPT4, and by their homologs AtIPT3, AtIPT5, AtIPT6, AtIPT7, and AtIPT8. To understand the dynamics of cytokinins in plant development, we comprehensively analyzed the expression of isopentenyltransferase genes of Arabidopsis. Examination of their mRNA levels and the expression patterns of the beta-glucuronidase (GUS) gene fused to the regulatory sequence of each AtIPT gene revealed a specific expression pattern of each gene. The predominant expression patterns were as follows: AtIPT1::GUS, xylem precursor cell files in the root tip, leaf axils, ovules, and immature seeds; AtIPT3::GUS, phloem tissues; AtIPT4::GUS and AtIPT8::GUS, immature seeds with highest expression in the chalazal endosperm (CZE); AtIPT5::GUS, root primordia, columella root caps, upper part of young inflorescences, and fruit abscission zones; AtIPT7::GUS, endodermis of the root elongation zone, trichomes on young leaves, and some pollen tubes. AtIPT1, AtIPT3, AtIPT5, and AtIPT7 were downregulated by cytokinins within 4 h. AtIPT5 and AtIPT7 was upregulated by auxin within 4 h in roots. AtIPT3 was upregulated within 1 h after an application of nitrate to mineral-starved Arabidopsis plants. The upregulation by nitrate did not require de novo protein synthesis. We also examined the expression of two genes for tRNA isopentenyltransferases, AtIPT2 and AtIPT9, which can also be involved in cytokinin biosynthesis. They were expressed ubiquitously, with highest expression in proliferating tissues. These findings are discussed in relation to the role of cytokinins in plant development.
TL;DR: In this article, the authors describe the development of a seed from embryo to the adult plant, including the growth of the cell wall and the root growth in the secondary growth stages of the seed.
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.
TL;DR: How processes such as abscission and dehiscence are regulated and the ways new research strategies are helping to understand the mechanisms involved in bringing about a reduction in cell-to-cell adhesion are examined are examined.
Abstract: ▪ Abstract Cell separation is a critical process that takes place throughout the life cycle of a plant. It enables roots to emerge from germinating seeds, cotyledons, and leaves to expand, anthers to dehisce, fruit to ripen, and organs to be shed. The focus of this review is to examine how processes such as abscission and dehiscence are regulated and the ways new research strategies are helping us to understand the mechanisms involved in bringing about a reduction in cell-to-cell adhesion. The opportunities for using this information to manipulate cell separation for the benefit of agriculture and horticulture are evaluated.