Root growth hormones

Phytoferritin transcription is induced by iron excess and repressed by iron deficiency in leaves as well as in roots in several plant species in the case of maize, there are two ferritin genes which are differentially regulated by two independent-signalling pathways, one involving an oxidative step and one dependent on the plant growth hormone, abscissic acid. 

As a hormone IAA has a broad range of effects on plants, altering tissue differentiation, root growth, cell elongation, and cell division.2413 The fastest observed response is an effect on cell elongation, which can be observed within 15-20 minutes.242 In A. thaliana IAA... 

Spiliotis, R. E., Root, A. W.,andBercu, B. B., Does growth hormone secretion increase during pubertal development Int. Congr. Ser.—Excerpta Med. 652, 1282 (1984). Stevens, R. L., Austen, K. F., and Nissley, S. P., Insulin-induced increase in insulin binding to cultured chondrosarcoma chondrocytes. J. Biol. Chem. 258, 2940-2944... 

Several in vitro tests are suitable for the determination of the growth-regulating activity of hormone-type herbicides, among them the straight growth test of wheat or oat, and the pea curvature test. Both methods yield quantitative results of good reproducibility. The Avena test elaborated by Went cannot be used in this case, but the root growth inhibition test is suitable (Audus, 1949 1951). 

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