BIO 1130 Lecture Notes - Lecture 5: Meristem, Auxin, Apical Dominance
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Plant growth and development: to understand diversity of plant structures and life histories, need to understand role that signal response pathways play in their growth and development. Signal response pathways: hormones and environmental stimuli alter behaviour of target cells, signal molecules bind to receptors in target cells, elicit cellular response (different response in different tissues, by means o a response pathway, signal can: I(cid:374)du(cid:272)e (cid:272)ha(cid:374)ges i(cid:374) (cid:272)ell"s shape or internal structure. Auxins: mainly indoleacetic acid (iaa, synthesized primarily in shoot apical meristem and young stems and leaves, promotes elongation of cells, governs growth responses to light and gravity. Auxin effects on stems: frequently promotes axial elongation of stems, maintains apical dominance. Inhibits growth of lateral meristems (branching: promote fruit development (cell division), inhibit leaf abscission, delay senescence. In roots, promote root initiation, growth of pre-existing roots, lateral branching of roots, formation of adventitious roots. Lateral root formation: root primordia in pericycle form lateral roots.