Accession Number:

AD0611618

Title:

RADIAL MOVEMENT OF C14-TRANSLOCATES FROM SQUASH PHLOEM,

Descriptive Note:

Corporate Author:

NATIONAL RESEARCH COUNCIL OF CANADA OTTAWA (ONTARIO) DIV OF BIOSCIENCES

Personal Author(s):

Report Date:

1964-07-23

Pagination or Media Count:

10.0

Abstract:

A time sequence study of the movement of C14assimilates at the tissue level was carried out with squash. Tissue of mature and immature petioles, stem, and hypocotyl were examined after 1-minute exposures of the primary leaf blade to C14O2. C14-Translocates were transported in the phloem from the mature leaf simultaneously toward the root and young organs of the upper plant. Rapid movement of the C14-front in the phloem was not due to gaseous diffusion of C14O2. Radial movement of C14-translocates occurred along the entire length of the phloem, ultimately supplying C14 to every living cell of the plant within 2 hours of assimilation. The velocity and rate of radial movement depended on the stage of development of each plant organ. Young and rapidly expanding petioles displayed maximum velocities of about 6 cmhour whereas older tissues showed velocities of about 1 cmhour. These values compared favorably with those known for protoplasmic streaming but contrasted sharply with the velocity of C14 conducted longitudinally in the phloem and estimated at between 250 to 300 cmhour. Radial movement of C14-translocates appeared to occur in the form of sucrose rather than stachyose, which suggested a differential permeability of the conducting elements of the phloem toward these two sugars. Author

Subject Categories:

Distribution Statement:

APPROVED FOR PUBLIC RELEASE