Mg-chelatase catalyzes the insertion of Mg2+ into protoporphyrin-IX (Proto) in the chlorophyll biosynthetic pathway. This is the first step unique to the chlorophyll pathway and is at the branchpoint between heme and chlorophyll biosynthesis. Previous work from our laboratory has shown that the enzyme from pea chloroplasts requires three distinct protein fractions (now known to contain the D, I and H subunits). The reaction requires ATP in two distinct steps: activation requiring two of the fractions (I and D) and metal ion insertion, requiring all three fractions. Work covered in this granting period includes the cloning and expression of the active form of one of the pea subunits and demonstration of the change in chromatographic behavior of the subunits upon activation with ATP.

The progress described in this report encompasses work supported by DOE grant DE-FG09-89ER13989 for the period 2/15/92 to the present 6/14/94. The goals of the project were to continue investigating the enzymology of Mg-chelatase and to investigate the co-regulation of heme and chlorophyll formation in intact plastids. During this period the laboratory had additional support (two years) from USDA to investigate heme metabolism in chloroplasts. This report is arranged so that the progress is described by reference to manuscripts which are published, under review or in preparation.

Chloroplasts are vital for life as we know it. At the leaf cell level, it is common knowledge that a chloroplast interacts with its surroundings – but this knowledge is often limited to the benefits of oxygenic photosynthesis and that chloroplasts provide reduced carbon, nitrogen and sulphur. This book presents the intricate interplay between chloroplasts and their immediate and more distant environments. The topic is explored in chapters covering aspects of evolution, the chloroplast/cytoplasm barrier, transport, division, motility and bidirectional signalling. Taken together, the contributed chapters provide an exciting insight into the complexity of how chloroplast functions are related to cellular and plant-level functions. The recent rapid advances in the presented research areas, largely made possible by the development of molecular techniques and genetic screens of an increasing number of plant model systems, make this interaction a topical issue.

This volume provides a comprehensive look at the biology of plastids, the multifunctional biosynthetic factories that are unique to plants and algae. Fifty-six international experts have contributed 28 chapters that cover all aspects of this large and diverse family of plant and algal organelles. The book is divided into five sections: (I): Plastid Origin and Development; (II): The Plastid Genome and Its Interaction with the Nuclear Genome; (III): Photosynthetic Metabolism in Plastids; (IV): Non-Photosynthetic Metabolism in Plastids; (V): Plastid Differentiation and Response to Environmental Factors. Each chapter includes an integrated view of plant biology from the standpoint of the plastid. The book is intended for a wide audience, but is specifically designed for advanced undergraduate and graduate students and scientists in the fields of photosynthesis, biochemistry, molecular biology, physiology, and plant biology.

Metabolism, Structure and Function of Plant Tetrapyrroles, Volume 90, the latest release in the Advances in Botanical Research series is a compilation of the current state-of-the-art on the topic. Chapters in this new release cover Tetrapyrrole Pigments of Photosynthetic Antennae and Reaction Centers of Higher Plants: Biochemistry, Biophysics, Functions, Molecular Mechanism of Antenna Regulation, Applications, Chlorophyll c: Synthesis, Occurrence, Light-Harvesting, Absorbance, Excitation Properties, Pigment Organization in Chlorophyll-Binding Proteins (FCP), Chlorophyll d and f: Synthesis, Occurrence, Light-harvesting, Absorbance, Excitation Properties, Pigment Organization in Chlorophyll-Binding Protein Complexes, Analysis of Chlorophyll, Precursors and Derivatives by New High-Performance Liquid Chromatography and Mass Spectrometry, and much more. Presents the latest release in the Advances in Botanical Research series Provides an Ideal resource for post-graduates and researchers in the plant sciences, including botany, plant biochemistry, plant pathology and plant physiology Contains contributions from internationally recognized authorities in their respective fields

Understanding seed-related processes is of major social, environmental, and economic concern. The viability and vigor of seeds are the very basis for sustainable agriculture and forestry, and comprehending the molecular and cellular events underlying these processes will become increasingly important to many economical sectors and for species that provide the world’s food supply. Seed Dormancy: Methods and Protocols covers analytical methods and approaches which have already lead to significant advances in the understanding of seed dormancy and germination. Chapters cover explanations of processes leading to the induction, maintenance, and termination of seed dormancy, the classification of different dormancy types, as well as an overview of protocols used for dormancy-termination of seeds of conifer species. This volume emphasizes methods essential for abscisic acid (ABA) analyses, including methods that have been important for receptor identification, analyses of ABA-catabolizing enzymes (the 8’-hydroxylases), and identification of novel signal transduction components, interacting partners, and/or response factors. The volume closes by addressing the development of new technologies, including spectroscopic methods (some of which allow for non-destructive sampling) as well as highly effective tissue-printing methods for seed dormancy research. Written in the successful Methods in Molecular BiologyTM series format, chapters include introductions to their respective topics, lists of the necessary materials and reagents, step-by-step, readily reproducible protocols, and notes on troubleshooting and avoiding known pitfalls. Authoritative and easily accessible, Seed Dormancy: Methods and Protocols features detailed methods that will prove invaluable for both applied and fundamental seed research.