Pathways of Hormone Movement

Basically two lines have been followed in the search for the pathways of hormone translocation (1) surgical methods and (2) autoradiographic methods which have come with the advent of radioactive hormones. Phloem-feeding aphids have been used as a speciality to detect translocation in sieve elements (for references see p lOOf.). 

By use of these various techniques it has been shown, especially for auxins, that hormones applied to the unfolded leaves of intact plants are generally 

3 Transport and Other Modes of Movement of Hormones (Mainly Auxins) 

There is increasing evidence, both from surgical techniques and autoradiographs, that stem sections behave similarly to intact stems with respect to the pathway of auxin transport. In stem sections of Coleus, Helianthus, Vida (Wan-GERMANN 1968, 1970, 1974, 1977, Wangermann and Withers 1978), and of Nicotiana (Sheldrake 1973 a) the transport of lAA was mainly associated with the phloem part of vascular tissue (see Fig. 3.3). On the other hand, lAA also moved basipetally in explants of Coleus free of vascular tissue (Mai 1934, Jacobs and McCready 1967) while in coleoptiles of Avena, Triticum, and Zea it has been shown that both parenchyma and vascular tissues take part in active basipetal auxin transport (Van der Weij 1932, Hertel and Leopold 1963, Wangermann and Withers 1978). 

1975) is probably the channel of a basipetal transport component (Konings 1968, 1969, Konings and Gayadin 1971, Davies et al. 1976, Pernet and Pilet 

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