Submitted to: American Journal of Potato Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/6/2006
Publication Date: 9/1/2006
Citation: Vega, S.E., Bamberg, J.B., Palta, J.P. 2006. Root zone calcium can modulate GA induced tuberization signal. American Journal of Potato Research. 83:135. Interpretive Summary: Potato is the top US vegetable. The edible part forms when underground stems (tubers) develop into storage organs for starch and other nutrients. In previous work, we showed the benefits of calcium fertilization for maintaining tuber quality and yield when the plant is under stress. It has long been known that the plant hormone gibberellin (GA3) has a strong inhibitory effect on tuber formation. Here for the first time, we investigated the interaction of the two factors, calcium and GA3, and show that the tuber-inhibiting effect of GA3 can be reversed by growing plants in a low calcium environment. Evidence of an interaction between GA3 and calcium provides clues to a better understanding of the physiological process by which the plant responds to stimuli to form tubers. Such knowledge might eventually be applied to better control of the tuber formation process in farmers’ fields.
Technical Abstract: The present study was conducted to investigate the possible relationship between root zone calcium and GA3 concentration in tuberization signal. For this purpose, we developed a system utilizing in vitro propagated potato plantlets and pure silica sand that allows precise control of root zone chemical composition and monitoring of tuberization. Root zone calcium concentration was controlled by continuously supplying a known solution hydroponically. Our results show that a strong tuberization signal can be induced by lowering calcium around the developing stolon in spite of the presence of GA3. As stated above, high GA inhibits tuberization. By lowering calcium we were able to overcome the inhibitory effect of GA3 on tuberization. Our preliminary studies provide first evidence for the modulation of GA3 control of tuberization by extracellular calcium. These studies have a strong possibility of opening new avenues for understanding the role of GA3 and calcium in the tuberization process.