Integrated Morphological, Physiological and Molecular Analysis of the Drought Response in Cultivated and Wild Prunus L. Subgenera Cerasus Species

Abstract

Knowledge about the genetic potential of wild Prunus species is important for recognizing gene pools in germplasm and developing effective strategies for germplasm conservation and breeding. In this study, cultivated sweet cherry (Prunus avium L.) and relative wild Cereus subgenus genotypes belonging to P. microcarpa Boiss and P. incana (Pall.) Batsch. species were assayed in controlled drought conditions performing an integrated morphological, physiological, genomic and transcriptomic analysis of the stress response. These analyses were performed under well-watered and water-deficient conditions analysing morphology of leaves, gas exchange parameters and chlorophyll content differently affected by drought, especially under long-term water deficiency. From a genomic point of view, these genotypes were characterized using simple sequence repeat (SSR) markers. Finally, in the analysis of the transcriptional responses, drought tolerance candidate genes were analysed by quantitative PCR (qPCR). From a morphological point of view, P. microcarpa showed less leaf area, height and diameter in comparison to P. incana and mainly P. avium. The highest rate of photosynthesis in genotypes differently was observed in the control treatment and the lowest rate viewed during stress. The analysed genes showed different responses to drought in the genotypes, and more detailed analysis techniques to explain the molecular mechanisms of drought tolerance are needed in these genotypes. Our results provide a significant contribution to the understanding of how P. incana and P. microcarpa respond to drought stress, which may help to explain molecular and physiological mechanisms associated with the response to the drought of cherries. Additionally, these results show that wild cherries can be considered as a genetic source of drought resistance in breeding programs.