Phototropic Auxin Redistribution in Corn Coleoptiles

Light Dosage and Phototropic Responses of Corn and Oat Coleoptiles

“…In this case, negative curvatures such as those found in Avena coleoptiles would be mediated by some mechanism other than lateral transport, and the hypothesis suggested above to account for negative curvature would be invalid. However, the results of Asana (2) and Wilden (34) indicate that following exposure of Avena coleoptiles to dosages of light which elicit negative curvature, there is indeed an auxin differential between light and dark sides, but that the highest amount of diffusible auxin is obtained from the lighted side-the reverse of that described for positive curvature (12,31). Asana Since all of the experiments described above were performed under dim red light, it was important to determine the relationship between the reciprocity failure described above and red light irradiation.…”

“…At least one of these must involve lateral translocation of auxin or a precursor (12). The nature of the other two responses, in terms of the role of auxin, will be considered in another paper describing detailed growth hormone studies.…”

“…Frequent distinction has been made between "tip curvature" and "base curvature" to distinguish between the phototropic responses of these two regions, and the two responses are discussed in detail in a review by Went (32). The experiments of Boysen-Jensen (6) and Boysen-Jensen and Nielsen (7) mediated by lateral migration of some substance, probably auxin or a precursor (12). However, in the second increment curvature (log MCS = 5.0) the physical barrier reduces but does not eliminate the curvature^response.…”

“…Zea coleoptiles were selected for the majority of the experiments described below since a certain amount of information was already available concerning their auxin relationships during phototropism (12). These coleoptiles are more suitable for auxin diffusion studies than those of Avena since they are larger in cross-sectional area, and consequently easier to manipulate.…”

Plant Growth in Relation to Endogenous Auxin, With Special Reference to Cereal Seedlings

“…Briggs, Tocher and Wilson (1957) found that coleoptiles when 90 hours old displayed their maximum growth rate, and at this time released mto agar the 'roughly maximal' amount of auxin. Suitable published data can be used to examine the accuracy of the proposition.…”