Az Eszterházy Károly Tanárképző Főiskola Tudományos Közleményei. 2004. Sectio Biologiae. (Acta Academiae Paedagogicae Agriensis : Nova series ; Tom. 25)

Tuba, Z., Takács, Z., Juhász, A. and Lichtenthaler, H. K.: Pentose-phosphate pathway as the possible background of resaturation respiration in the desiccation-tolerant lichen Cladonia convoluta

Acta Acad. Paed. Agriensis, Sectio Biologiae XXV (2004) 153-12

6 Pentose-phosphate pathway as the possible background of resaturation respiration in the desiccation-tolerant lichen Cladonia convoluta Tuba, Z.

1'

2, Takács, Z.

1, Juhász, A.

2, Lichtenthaler, H. K.

3 'Plant Ecology Departmental Research Group of the Hungarian Academy of Sciences at the 2 Department of Botany and Plant Physiology, Faculty of Agricultural and Environmental Sciences, Szent István University, H-2100, Gödöllő, Páter K. u. 1. 3 Botanisches Institut der Universitat Karlsruhe, Lehrstuhl II, D-76128, Karlsruhe, Germany Abstract. Respiration rates in the re-wetted desiccated thalli of a desiccation-tolerant lichen Cladonia convoluta were measured during rehydration and revival. Treatment with bromoxynil as uncoupler of oxidative phosphorylation showed that the high intensity of resaturation respiration rate is not entirely caused by the uncoupled mitochondrial membrane. Treatments with KCN or absence of 0

2 obtained by applying N

2 resulted in the same effect indicating the possible role of the pentosephosphate shunt in the boosted C0

2 efflux of the rehydrating and reviving desiccated lichen thalli. Keywords: basic respiration, bromoxynil, Cladonia, uncoupling, desiccation tolerance, mitochondrion, potassium cyanide, rehydration, wetting burst Introduction Desiccation tolerant plants can survive the loss of 80-95% of their cell water, so that the plants appear completely dry and no liquid phase remains in their cells; after a shorter or longer period in the desiccated state, they revive and resume normal metabolism when they are re-moistened (Proctor et al., 2002). In a dehydrated desiccation tolerant plant an intense C0

2