Hypocotyl elongation

Cosio C. Vuillemin L. De Meyer M. Kevers C. Penel C. Dunand C. (2009) An anionic class III peroxidases from zuccini may regulate hypocotyl elongation through its auxin oxidase activity / / Planta. V. 229. P. 823-836. 

Hypocotyl elongation was not linear with time, except in the seeds pretreated in DCM alone (r = 0.99). Initially the pretreatment and DMF retarded hypocotyl elongation, compared to the water control. Chondri 11 asterol in DCM pretreatment relieved the inhibition somewhat by 96 h. After 72 h chondrillasterol in DMF... 

As shown by measurement of root and hypocotyl elongation, the treatment with the RO fraction did not prevent the initial absorption of water by the seed, which is essentially a passive process. However, it effectively inhibited the ensuing expansion of these organs, which results from a combination of cell expansion and cell division. As late as 46 h after seed imbibition, no sign of cell division was visible in roots from seeds treated with 1 8- and 1 10-diluted RO fraction, and only occasional divisions, mainly in the procambial area, were observed after treatment at 1 14 dilution. By contrast, control roots resumed active cell division within 16 h after imbibition. As a conspicuous consequence of the inhibition of cell expansion/division activity, the apex of roots from treated seeds appeared distinctly... 

Rice lamina inclination test Radish seedling elongation Tomato hypocotyl elongation Wheat leaf-unrolling Pea inhibition ... 

Adventitious Root Formation. IAA stimulates adventitious root formation in cucumber hypocotyl cuttings (28). On the other hand, BR has either no effect or is slightly inhibitory, while it stimulates hypocotyl elongation. Gibberellin is usually inhibitory. However, it has been reported that in mung bean cuttings, the formation of root primordia was not inhibited (29). 

Total cell numbers of hypocotyl segments after treatments were observed under the microscope to see whether the brassinolide-induced growth stimulation was due to cell elongation or cell division. As shown in Table I, the cell number of epidermal cells was not changed during 8 h incubation, suggesting that brassinolide-induced hypocotyl elongation is caused by cell expansion and not by cell division. 

A fungal product termed KM-01 retards the promoting effects of brassinolide on rice lamina bending and radish hypocotyl elongation, but nothing is known about the mode of action [85]. 

Another compound with plant hormone-like activity is raphanusanin, a natural inhibitor of radish hypocotyl elongation which is believed to be instrumental in its phototropic response [179]. Raphanusanin has been reported to prevent auxin-induced MT reorientations [19]. However, there is no direct evidence that raphanusanin exerts an effect on MTs. 

A variety of second messengers have been implicated in auxin signaling including phosphatidylinositol, calcium, and the products of phospholipase A (PLA) enzyme. Since most of these reports have been in the literature for some time, they will not be discussed here (see [47] for review). Recent reports have provided additional evidence for a role for PLA in auxin action. Earlier studies by Andre and Scherer [48] showed that auxin treatment resulted in an increase in PLA activity in a number of plant species suggesting that a product of this enzyme functions as a signaling molecule. Consistent with this possibility, inhibitors of mammalian PLA inhibit auxin-induced hypocotyl elongation in... 

Other plant hormones, such as auxins and GAs. Finally, selected compounds were assayed using a cress hypocotyl elongation test. It has been demonstrated that cress is very sensitive to an internal deficiency of BRs and is therefore a useful species for evaluating BR biosynthesis inhibitors [7-8],... 

To investigate the biosynthetic steps affected by brassinazole, we examined the effect of biosynthetic intermediates downstream from cathasterone on hypocotyl elongation of brassinazole-treated Arabidopsis [9]. The feeding experiment suggests that the target(s) of brassinazole could be the two-step conversion of... 

Raphanus sativus L. On the contrary, the inhibitors that cause the etiolated radish hypocotyl to curve phototropically have been identified as cis- and trans-m-phanusanin, and raphanusamide [7]. The raphanusanins, particularly, inhibited hypocotyl elongation in vitro and, if applied unilaterally, caused curvature [11]. 

Shibata K, Kubota T, Kamisaka S (1974) Isolation and chemical identification of a lettuce cotyledon factor, a synergist of the gibberellin action in inducing hypocotyl elongation. Plant Cell Physiol 15 191-194... 

There is extensive evidence that GA increases auxin levels either by enhancement of auxin biosynthesis (Jindal and Hemberg 1976, Sastry and Muir 1965) or by retardation of auxin destruction (Kogl and Elema 1960). Nevertheless, there is convincing evidence that GA can also stimulate elongation independently of auxin (Kazama and Katsumi 1974, Cleland et al. 1968, Kaufman et al. 1969). In excised Avena stem internodes, for example, GA stimulates cell elongation, while auxin is inhibitory (Kaufman et al. 1969). Similarly, stimulation of lettuce hypocotyl elongation has been used as a bioassay for GA, while... 

White light inhibits hypocotyl elongation in a variety of seedlings. In some cases this can be overcome by GA. In hypocotyls of Lupinus albus, lAA largely overcomes white light inhibition of hypocotyl growth while GA is ineffective (Acton and Murray 1974). 

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