New insights into how seeds are made

Citation: Sabelli PA and Larkins BA (2015) New insights into how seeds are made. It is difficult to overstate the importance of seeds for the evolutionary success of the spermato-phytes and the development of human cultures and their survival. For hundreds of millions of years since their appearance in the Devonian period, seed plants have colonized many environments , thanks in part to several adaptations, including seed formation. Seeds can spread over large areas over long time spans, while also protecting the embryo from pathogens and adverse environmental conditions. Seeds vary greatly in shape and structure, but they typically possess three major components: the sporophyte (i.e., the embryo), a storage metabolite compartment (i.e., cotyledons, endosperm or perisperm) enabling the early growth of the seedling before it is autotrophic, and a protective coat. Since agriculture began around 10,000 years ago, certain seed plants have been domesticated and methodically bred to provide food and raw materials. Today, vast swaths of land are planted to a few grain crops that have proven highly nutritious and productive. In view of the exploding (and generally more affluent) human population, which is projected to reach nine billion by mid-century, crop genetic erosion, constrained fossil fuel availability, and global climate change put enormous pressure on agriculture. The continuous genetic improvement of seed plants has played a key role in sustaining the human population for thousand of years, but additional improvements are necessary in the future. A clear understanding of the biological processes controlling seed development, quality, and yield is required to meet the challenges facing agriculture. Our comprehension of seed development has progressed considerably, thanks to model plant systems, development of high through-put techniques, and increased understanding of genetic and biochemical pathways. The goal of this Research Topic on Advances in Seed Biology is to update key aspects of seed development, evolution and physiology. The first step in seed formation is a double fertilization event, which involves the egg cell and central cell in the female gametophyte each fusing with a sperm cell. This process is tightly regulated, and Bleckmann et al. (2014) describe the complex signaling pathways that control pollen tube growth, communication with female flower structures, and gametes interaction. The fertilized egg and central cell go on to form the embryo and the endosperm, respectively, by multiplying and expanding through several variant cell cycles, such as mitotic cell proliferation, acytokinetic mitosis, and endoreduplication. Dante et …