BIOL-1507EL Lecture Notes - Lecture 1: Meristem, Cytokinin, Gibberellin
21 Dec 2019
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Document Summary
Gibberellins also stimulate growth, including elongation of stems. Ethylene regulates a range of responses, including senescence. Abscisic acid suppresses growth and influences responses to environmental stress. Jasmonates and oligosaccharins regulate growth and have roles in defence. Synthesized primarily in shoot apical meristem and young stems and leaves. Promote elongation of cells in coleoptiles and stems. Govern growth responses to light and gravity. Promote stem elongation, help seeds and buds break dormancy. Stimulate cell division, promote leaf expansion, and retard leaf aging. Ratios of auxin to cytokinin affect growth of roots and shoots. Present in fruits, flowers, seeds, leaves, roots. Senescence: removal of seed pods in soybean delays senescence since ethylene is not produced. Highest concentration in shoot tips and developing seeds and embryos. Synthesized from carotenoid pigments inside plastids in leave. Promotes stomatal closure; may trigger seed and bud dormancy. Several signal response pathways operate in plants. Second-messenger systems enhance the plant cell"s response to a hormone"s signal.
