Effects of temperature and sink activity on the transport of14C-labelled indol-3yl-acetic acid in the intact pea plant (Pisum sativumL.)

✍ Scribed by J. Eliezer; D. A. Morris

• Publisher: Springer-Verlag
• Year: 1979
• Tongue: English
• Weight: 890 KB
• Volume: 147
• Category: Article
• ISSN: 0032-0935
• DOI: 10.1007/bf00388741

✦ Synopsis

The velocity and intensity of basipetal transport of ~4C-labelled indol-3yl-acetic acid (IAA) applied to the apical bud of the intact pea plant were influenced by the temperature to which the stem was exposed and were not influenced by changes in the temperature of the root system when this was controlled independently between 5~ and 35 ~ C. The velocity of transport increased steadily with temperature to a maximum in excess of 35 ~ C and then fell sharply with further increase in temperature. The Qto for velocity, determined from Arrhenius plots, was low (ca. 1.3). Transport intensity increased to a maximum at about 25 ~ C (Qlo=2.2) and then declined gradually with further increase in temperature. It is suggested that transport velocity and transport intensity are controlled independently.

The characteristics of auxin transport through the stem were not affected by removal of the root system, or by the withdrawl of root aeration. Labelled IAA did not pass a region of the stem cooled to about 1.0 ~ C, or through a narrow zone of stem tissue killed by heat treatment. In the latter case the heat treatment was shown not to interfere with the upward transport of water in the xylem. Labelled IAA continued to move into, and to accumulate in, the tissues immediately above a cooled or heat-killed region of the stem. It was concluded that the long-distance basipetal transport of auxin through the stem of the intact plant is driven by the transporting cells themselves and is independent of the activity of sinks for the transported auxin.