Spectral and dose dependence of light-induced ion flux responses from maize leaves and their involvement in leaf expansion growth |
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Authors: | Zivanović Branka Dusan Cuin Tracey Ann Shabala Sergey |
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Affiliation: | School of Agricultural Science, University of Tasmania, Private Bag 54, Hobart, Tasmania 7001, Australia. |
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Abstract: | Two types of segments (intact leaf tissue and isolated mesophyll tissue respectively) were isolated from basal (still growing) and tip (non-growing) maize leaf regions. The leaf segments were exposed to different light qualities (blue or red light) and quantities, and net fluxes of K+, Ca2+ and H+ were measured non-invasively using ion-selective vibrating microelectrodes (the MIFE technique). A clear dose dependency of all ion flux responses on both red (RL) and blue (BL) light fluence rate was found. We provide evidence that light-induced K+ flux kinetics are different between growing and non-growing tissues and attribute this difference to the direct involvement of RL-induced K+ flux in turgor-driven leaf expansion growth controlled by the epidermis, as well as to the charge-balancing role of K+ in the leaf mesophyll. Generally, BL was much more efficient in stimulating K+ uptake in the growing basal region compared with RL. We also show a much stronger influence of RL on Ca2+ fluxes in the basal region compared with BL, which argues in favor of the importance of RL in Ca2+ signaling during leaf growth. |
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Keywords: | Expansion growth - Ion fluxes - Ion-selective microelectrodes - Light - Photosynthesis - Zea mays L |
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