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bioRxiv · 10.1101/2022.11.24.517516

ALMT-independent guard cell R-type anion currents

Jaslan, J.·Marten, I.·Jakobson, L.·Arjus, T.·Deeken, R.·Sarmiento, C.·De Angeli, A.·Bosche, M.·Kollist, H.·Hedrich, R.
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Abstract

Plant transpiration is controlled by stomata, with S- and R-type anion channels playing key roles in guard cell action. Arabidopsis mutants lacking the ALMT12/QUAC1 R-type anion channel function in guard cells show only a partial reduction in R-type channel currents. To identify the molecular nature of the remaining R-type anion channel population, patch clamp studies were performed. This R-type current fraction in the almt12 mutant exhibited the same voltage dependence, susceptibility to ATP block and lacked a chloride permeability as the wildtype. Therefore, we asked whether the R-type anion currents in the ALMT12/QUAC1-free mutant are caused by additional ALMT isoforms. In wildtype guard cells ALMT12, ALMT13 and ALMT14 transcripts were detected, whereas only ALMT13 was found expressed in the almt12 mutant. Substantial R-type anion currents still remained active in the almt12/13 and almt12/14 double mutants as well as the almt12/13/14 triple mutant. This situation, supported by transpiration measurements, suggests that, with the exception of ALMT12, channel species other than ALMTs carry the guard cell R-type anion currents.

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Jaslan, J., Marten, I., Jakobson, L., Arjus, T., Deeken, R., Sarmiento, C., De Angeli, A., Bosche, M., Kollist, H., Hedrich, R.. 2022-11-24. ALMT-independent guard cell R-type anion currents. https://doi.org/10.1101/2022.11.24.517516

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