Fusicoccin counteracts inhibitory effects of high temperature on auxin-induced growth and proton extrusion in maize coleoptile segments.

Plant growth and development are tightly regulated by both plant growth substances and environmental factors such as temperature. Taking into account the above, it was reasonable to point out that indole-3-acetic acid (IAA), the most abundant type of auxin in plants, could be involved in temperature- dependent growth of plant cells. We have recently shown that growth of maize coleoptile segments in the presence of auxin (IAA) and fusicoccin (FC) shows the maximum value in the range 30-35 degrees C and 35-40 degrees C, respectively.

The effect of auxins (IAA and 4-Cl-IAA) on the redox activity and medium pH of Zea mays L. root segments.

Indole-3-acetic acid (IAA) and 4-chloroindole-3-acetic acid (4-Cl-IAA) were tested at different concentrations and times for their capacity to change the redox activity and medium pH of maize root segments. The dose-response surfaces (dose-response curves as a function of time) plotted for redox activity and changes in medium pH (expressed as DeltapH) had a similar shape for both auxins, but differed significantly at the optimal concentrations. With 4-Cl-IAA, the maximal values of redox activity and medium pH changes were observed at 10(-10) M, which was a 100-fold lower concentration than with IAA.