Artificial seeds

Artificial Seeds Explained: Synthetic Seed Production, Desiccated and Hydrated Systems, Alginate Beads, Applications and Latest Advances DESCRIPTION What if we could build a seed ourselves, around an embryo made in the lab? This animated lesson covers artificial (synthetic) seeds from start to finish. We define them (large scale production of somatic embryos and their encapsulation: a bead of gel holding a somatic embryo or shoot bud, with nutrients, growth regulators, pesticides and antibiotics), compare a true seed with an artificial one part by part (embryo, artificial endosperm, capsule), and trace the history: Murashige's idea (1977), the first desiccated carrot seeds coated with Polyox by Kitto and Janick, the calcium alginate beads of Redenbaugh and colleagues in alfalfa and celery, and the encapsulated mulberry shoot buds of Bapat and colleagues (1987). We look at what goes inside the bead (somatic embryos, shoot buds, nodal segments, orchid protocorm like bodies), then the two systems. In the desiccated system, embryos are hardened with a polymer coat or with ABA during maturation and then dried. In the hydrated system, embryos are enclosed in gels, and calcium alginate is the most suitable. We walk through the classic method step by step (2% sodium alginate dripped from a burette into 100 mM calcium chloride, an embryo inserted into each drop, 20 to 30 minutes to harden, then washing and planting) and explain the chemistry of the "egg box" gel. We cover what can be added to the gel, the problems of hydrated seeds and their fixes (stickiness, drying, waxy coatings, short storage), a desiccated vs hydrated comparison, eight applications, the limitations, the problems still to be solved, and the difference between germination and conversion. We finish with recent advances: germplasm conservation and exchange, cryopreservation by encapsulation dehydration and encapsulation vitrification, double layered beads, manufactured seed for conifers, and scale up with bioreactors and automation. Chapters 0:00 Introduction 0:33 What is an artificial seed? 1:18 True seed vs artificial seed 2:00 History 2:54 What goes inside the bead? 3:25 Two systems 3:42 Desiccated system 4:36 Hydrated system 5:06 Making alginate beads, step by step 5:51 The chemistry: the "egg box" 6:43 What the gel can carry 7:18 Hydrated seeds: problems and fixes 7:55 Desiccated vs hydrated 8:30 Applications 1-4 9:16 Applications 5-8 9:51 Limitations 10:28 Problems still to solve 11:03 Germination vs conversion 11:33 Advances: conserving and sharing germplasm 12:20 Advances: making artificial seeds work better 13:07 Recap Topics covered: artificial seeds, synthetic seeds, somatic embryos, encapsulation, shoot buds, nodal segments, protocorm like bodies, artificial endosperm, Murashige, Kitto and Janick, Polyox, Redenbaugh, Bapat, desiccated system, hydrated system, ABA, abscisic acid, hardening, sodium alginate, calcium chloride, calcium alginate, egg box model, gels (agar, agarose, gelrite, carrageenan, sodium pectate), waxy coating, Elvax, storage, sterile plants, fixation of hybrid vigour, transgenic plants, virus free plants, limitations, quiescence, germination, conversion, germplasm conservation, cryopreservation, encapsulation dehydration, encapsulation vitrification, double layered beads, manufactured seed, bioreactors. Sources for the history and advances: Murashige (1977) Acta Horticulturae 78: 17-30; Kitto and Janick (1985) Journal of the American Society for Horticultural Science 110: 277-282; Redenbaugh et al. (1986) Bio/Technology 4: 797-801; Bapat, Mhatre and Rao (1987) Plant Cell Reports 6: 393-395; Senaratna, McKersie and Bowley (1989) Plant Science 65: 253-259; Fabre and Dereuddre (1990) Cryo-Letters 11: 413-426. Course: Principles of Plant Biotechnology