Chlorophylls content and photosynthetic efficiency in two sour cherry (Prunus cerasus L.) genotypes under drought stress

Abstract

The drought is limiting factor in fruit production today. Identification of sour cherry genotypes tolerant to drought will enable the sustainability of fruit production. The aim of our study was to select sour cherry genotypes according to their genetic background as well as drought tolerance and investigate possible mechanisms of drought tolerance through the changes in photosynthetic apparatus (i.e. photosynthetic pigments content) and photosynthesis process assessed through chlorophyll fluorescence transient. All together with molecular markers (SSRS and AFLPs), relative water content (RWC), as indicator of plant water status, sort out two genotypes (Kelleris 16 and OS) opposite in regards to drought tolerance. Down-regulation of photosynthesis in drought treated Kelleris 16 plants was seen as changes in antenna complexes of PSII (decreased total chlorophylls content (a+b) and chlorophylls ratio (a/b)). Despite unchanged maximum quantum yield of PSII in drought treated leaves of genotype OS, overall photosynthetic performance expressed as PI_ABS was down-regulated in both investigated genotypes. However, decrement of PI_ABS were much pronounced in genotype Kelleris 16 mainly because of changes in a certain fraction of RCs which become dissipative centres, seen as increase in ABS/RC and DI₀/RC, in order to avoid photooxidative damage of photosynthetic apparatus. Also, electron transport, seen as decrease in ET₀/(TR₀-ET₀) and ET₀/RC, was impaired which lead to poored CO₂ fixation and photosynthesis. Described changes in functioning of photosynthetic apparatus in drought treated plants of Kelleris 16 are main distinction between two investigated genotypes regarding to drought adaptation mechanisms.