Embryogenesis.pdf

How has land plant anatomy evolved? • Critical Characteristics Include: -maintenance of cell water. -gas exchange in air and not in water. -physical support so that the plant can obtain light. -the ability to acquire nutrients from soil rather than water. -the ability to reproduce on land. -the abil...

How has land plant anatomy evolved? • Critical Characteristics Include: -maintenance of cell water. -gas exchange in air and not in water. -physical support so that the plant can obtain light. -the ability to acquire nutrients from soil rather than water. -the ability to reproduce on land. -the ability to control and coordinate growth. Embryogenesis • Basic references: • Campbell & Reece. 8th edition. pp.807-809. • Taiz & Zeiger. 6th edition. pp. 477-482; Figure 17.3; pp.808-809. • . Polarised arrangement 4h After fertilisation (elongated) (embryo) (suspensor) (Retains the vacuole) 1-cell 2-cell 8-cell E globular Suspensor Maternal tissue SAM Embryonic RAM Axial polarity E Heart L Heart Bilateral symmetry “torpedo” Mature, resting Ten days (0.5 mm) About 20,000 cells Establishment of Axial Polarity About 30 h (Shoot apex Cotyledons) Hypocotyl and root axis (One lens-shaped cell) (quiescent centre and Root cap stem cells) (nonembryonic) Embryogenesis Establishment of axial polarity Cell patterning Embryo mutants Monopteros (mp) mutant Gnom (gn) mutant Monopteros (mp) genes • Auxin response factors (ARF) hypophysis • Zygote ( a single cell) Embryogenesis • Mature embryo (multicellular,miniature plant resting within a seed) • Germination • Post-embryonic growth and development -primary plant growth (young plant body) -secondary plant growth • Reproductive development