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Early Plant Formation

Early Plant Formation - • formation of roots/shoots...

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Early Plant Formation root-shoot axis  - regulating amount/pattern of cell division >> 3D shape/form cells w/ multiple potentials restricted to meristemic regions apical meristems establish axis in embryogenesis tissue systems organized radially around axis food source for embryo - endosperm in angiosperms, megagametophyte in gymnosperms 1st division of zygote >> smaller cell becomes embryo, larger cell forms suspensor (links embryo to nutrient tissue in seed) o cells near suspensor >> root o cells at other end >> shoot embryo stops suspensor from developing into another embryo tissue systems  - dermal tissue, ground tissue, vascular tissue dermal tissue - from protoderm, outermost cells of embryo o divides w/ cell plate perpendicular to surface ground tissue - functions in food/water storage vascular tissue - from procambium at embryo core o functions in water/nutrient transport
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Unformatted text preview: • formation of roots/shoots controlled independently • morphogenesis - generation of form, produces the cotyledon(s) • seeds need enough nutrients to support sporophyte until it can photosynthesize o can’t bury seeds to deep germination - radicle (1st root) extends through seed coat • orients so that roots grow down, shoots grow up • starts when seed absorbs water, metabolism resumes • most seeds must stratify (spend time in cold conditions) before germinating o ensures that seed will not sprout right before cold season • amyloplasts- starch-storing plastids, provides metabolic reserves for young plant • cotyledon >> scutellum (food source used before endosperm) • aleurone- outer layer of endosperm, signaled by gibberellic acid to produce amylase • seed very susceptible to disease/drought between germination and young plant stage...
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