The five chemical messengers of a plant: auxins, gibberellins, cytokinins, ethylene and abscisic acid. What each one does, the experiments that found them, and how they work together.
3 lessons, about 1 h 35 min3 simulations10 problems3 practice questionsPython in every lesson
Created by StemPy LabA plant growth regulator is a small chemical made by the plant that controls growth, in a very small amount. There are five groups: auxins, gibberellins, cytokinins, ethylene and abscisic acid. Darwin, Boysen-Jensen, Paal and Went showed that the tip of a coleoptile sends down a substance, auxin, that makes the stem bend. Auxins root cuttings, keep apical dominance, make seedless fruit and kill dicot weeds.
Gibberellins are terpenes that make the stem longer. They were found through the bakanae, or foolish seedling, disease of rice, which is caused by the fungus Gibberella fujikuroi. They give long grape stalks, delay senescence, speed malting, raise sugarcane yield and make rosette plants bolt. Cytokinins are adenine derivatives that make cells divide, delay senescence and overcome apical dominance.
Ethylene is a gas, made by ripening fruit and ageing tissue, that ripens fruit, causes the respiratory climacteric, and promotes senescence and abscission. Ethephon releases it. Abscisic acid is the stress hormone. It closes stomata, keeps seeds dormant and helps seeds to survive drying, and it is an antagonist of gibberellins.
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