About this Research Topic
Chloroplasts are plant and eukaryotic algal cell organelles that convert light energy into relatively stable chemical energy via the photosynthetic process. By doing so, they sustain life on Earth. Chloroplasts also provide diverse metabolic activities for plant cells, including the synthesis of fatty acids, membrane lipids, isoprenoids, tetrapyrroles, starch and hormones. Following the previous Research Topic on Structure and Function of Chloroplasts, in this second edition, we aim to update the latest developments on the biogenesis, morphogenesis, protection and senescence in maintenance of the structure and function of chloroplasts.
Chloroplasts are enclosed by an envelope of two membranes which encompass a third complex membrane system, the thylakoids, including grana and stroma lamellae. In addition, starch grains, plastoglobules, stromules, eyespots, pyrenoids, etc., are also important structures of chloroplasts. It is widely accepted that chloroplasts evolved from a free-living photosynthetic cyanobacterium, which was engulfed by an eukaryotic cell. Chloroplasts retain a minimal genome, e.g., most of the chloroplast proteins are encoded by nuclear genes and the gene products are transported into the chloroplast through complex import machinery. The coordination of nuclear and plastid genome expression establishes the framework of both anterograde and retrograde signaling pathways. As the leaf develops from the shoot apical meristem, proplastids and etioplastids differentiate into photosynthetically active chloroplasts. Chloroplasts are divided by a huge protein complex, also known as the plastid-dividing (PD) machinery, and their division is regulated by many factors to maintain an optimized number and size of chloroplasts in the cell. These processes are fundamental for the biogenesis and three-dimensional dynamic structures of chloroplasts.
Accompanying photosynthesis, reactive oxygen species (ROS) and other cellular signals can be generated. As an important metabolic hub of the plant cell, the chloroplast functional status has been found to be critical for a variety of abiotic and biotic stresses, including drought, high light, cold, heat, oxidative stresses, phosphate deprivation, and programmed cell death at sites of infection. Therefore, a better understanding of the responses of chloroplasts to these stresses is part of understanding how the plant itself responds to these stresses. Ultimately, this knowledge will be necessary to engineer plants to be more resistant to common stresses.
Following the previous edition, we aim to cover in this new Research Topic the recent advances on understanding the structure and biological functions of chloroplasts, including lipid biosynthesis and membrane function, photosynthesis, metabolism, signaling, protein structure, and biogenesis, development and morphology of chloroplasts. This Research Topic will therefore continue to serve the researchers in the field and welcomes all tier one type articles (e.g. Original Research, Review, Methods, Opinion and Perspective articles).
Dr. Deqiang Duanmu based at Huazhong Agricultural University in China is collaborating with Dr. Gao, Dr. Soll, Dr. Rosten, Dr. Lu and Dr. Liu as an editorial assistant in this Research Topic.
Keywords: Chloroplast, Envelope, Thylakoid, Protein Import, Photosynthesis
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