Gibberellins and Light Regulated Petiole Growth in Thlaspi arvense L

AUTOR(ES)

Metzger, James D.

RESUMO

Petiole growth in Thlaspi arvense L. was stimulated when a basic 8 hour photoperiod (4.20 milliwatts per square centimeter) was extended with low intensity light (0.16 milliwatt per square centimeter) from incandescent lamps. The day length extension was effective only when the light contained high proportions of far red light. Exogenous gibberellin A3 (GA3) could partially substitute for the promotive effect of the extended photoperiod. Moreover, the GA biosynthesis inhibitor 2-chlorocholine chloride inhibited the increase in petiole growth induced by the extended photoperiod. However, evidence was obtained indicating that gibberellins do not mediate the effect of the extended photoperiod. First, petiole growth was greater in plants receiving both exogenous GA3 and a day length extension than the sum of the effects of the two treatments alone. Second, petioles were sensitive to exogenous GA3 only during the early stages of leaf development, whereas mature (but not senescent) leaves continued to respond to an extension of the photoperiod. Third, the cellular basis for growth induced by extending the photoperiod was different from that observed with GA3. It was concluded that light and gibberellins are both important in the overall regulation of petiole growth, but act through independent mechanisms.

Documentos Relacionados

• Localization of the Site of Perception of Thermoinductive Temperatures in Thlaspi arvense L
• Thermoinductive Regulation of Gibberellin Metabolism in Thlaspi arvense L. (II. Cold Induction of Enzymes in Gibberellin Biosynthesis).
• Gibberellins and Light Inhibition of Stem Growth in Peas 12
• Cloning and sequencing of a full-length cDNA from Thlaspi arvense L. that encodes a cytochrome P-450.
• Distribution of Gibberellins in Lathyrus odoratus L. and Their Role in Leaf Growth.