Cell elongation regulation

Cocucci, R. DeMichelis, M. I. Regulation of proton extrusion by plant hormones and cell elongation. Phusiol. Veg., 1975, 13(4), 797-811. 

Kim, H.J. and Triplett, B.A., Regulation of gene expression in the transition from cell elongation to secondary wall formation in cotton fiber. Proceedings of the Beltwide Cotton Conferences, National Cotton Council, Memphis, TN, 2005, 1043. 

There are several ways to alter effective levels of putative hormones. The first is to excise a plant tissue that is incapable of synthesizing the hormone itself, and allow the tissue to become depleted of the hormone. If this causes cessation of a particular response, and upon readdition of the compound the response is restored, there is reason to believe that the compound is a hormone controlling that process. For example, excision of sections of coleoptiles results in a marked decline in growth rate [13]. Since auxin can restore the growth rate, while none of the other hormones can substitute for auxin, the evidence that coleoptile cell elongation is regulated by auxin is strong. 

Auxins control many aspects of plant growth and development. Physiological processes such as cell elongation, cell division, differentiation, tropisms, rooting, fruit development and abscission are influenced by auxin [ 16,50,62]. However, the mechanism by which this hormone regulates diverse physiological processes is... 

---