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Title: ROOT ZONE CALCIUM CAN MODULATE GA INDUCED TUBERIZATION SIGNAL

Author
item VEGA, SANDRA - UNIV OF WISC
item PALTA, JIWAN - UNIV OF WISC
item Bamberg, John

Submitted to: American Journal of Potato Research
Publication Type: Abstract Only
Publication Acceptance Date: 4/15/2005
Publication Date: 3/10/2006
Citation: Vega, S.E., Palta, J.P., Bamberg, J.B. 2006. Root zone calcium can modulate GA induced tuberization signal [abstract]. American Journal of Potato Research. 83:135.

Interpretive Summary:

Technical Abstract: Among the known hormones, the most convincing case for a critical role in the control of tuberization, has been made for plant hormone gibberellin. High GA level is known to inhibit tuberization, and tuberization is promoted by reducing GA level. Calcium is known to be a second messenger regulating many developmental processes in plants. A wide range of signals such as light, hormones, gravity, touch, wind, cold, drought, oxidative stress and fungal elicitors have been shown to be linked to perturbation of cytoplasmic Ca2+ concentration. Several studies have implicated that GA is transduced by an increase in Ca2+ concentration and calmodulin levels. Using in vitro propagated potato plantlets and continuously maintaining root zone calcium, we have recently demonstrated that tuber number and tuber size are controlled by root zone calcium. It appears that a strong tuberization signal can be induced by lowering calcium around the developing stolon. The present study was conducted to investigate the possible relationship between root zone calcium and GA concentration in tuberization signal. For this purpose, we developed a system utilizing 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 as a drip. We were able to override the inhibition of tuberization by GA, by lowering extracellular calcium. As stated above, high GA inhibits tuberization. By lowering calcium we were able to overcome the inhibitory effect of GA on tuberization. Our preliminary studies provide first evidence for the modulation of GA control of tuberization by extracellular calcium. These studies have a strong possibility of opening new avenues for understanding the role of GA in the tuberization process.