Stress-mediated effects on the expression of a predominant 18-kDa Taraxacum officinale root protein

A predominant 18-kDa protein is present in the roots of dandelion (Taraxacum officinale Weber) which undergoes a small decline in amount in autumn and a small increase in spring. This has led to the suggestion that the protein is a vegetative storage protein (VSP). Long-term photoperiod and temperature changes applied to dandelion plants under controlled conditions did not result in fluctuations in the amount of the 18-kDa protein in the root. A rapid decrease in temperature from 20 to 5 °C (cold-shock) resulted in an increase in the relative amount of the 18-kDa protein transcript, but no change in the amount of the protein within the root. Conversely, a warm-shock treatment (the transfer of plants from 5 to 20 °C) caused a decline in the 18-kDa protein transcript, and a decline in the quantity of the 18-kDa root protein. Defoliation and wounding at 5 °C both stimulated an increase in the 18-kDa protein transcript within 36 h, but there was no change in protein amount. Subjecting the plants to these perturbations at 20 °C was without effect. The application of water stress to the dandelion plants had no effect on the 18-kDa protein transcript, nor on the amount of protein present in the roots. These responses of the 18-kDa protein and its gene are not consistent with those of known VSPs.