Identification of differential expressed transcripts of almond (Prunus dulcis ‘Sefied’) in response to water-deficit stress by cDNA-AFLP

Abstract

Drought is the major abiotic stress with adverse effects on growth and productivity of plants. It induces the expression of various genes that are involved in stress response and tolerant/sensitive phenotypes. In this study, the expression of several genes were analyzed in response to dehydration in almond (Prunus dulcis 'Sefied') to shed light on the underlying genetic basis of water-deficit tolerance in almond. The advantages of using almond as a model system for studying dehydration tolerance in woody species are its small diploid genome and its adaptation to drought. Differential expression technique, cDNA-AFLP (amplified fragment length polymorphism), was used to find transcripts accumulated in young trees subjected to water-deficit treatment. Twenty transcript-derived fragments (TDFs) with differential expression between control and stress conditions were generated, amplified, and sequenced. The TDFs showing high homology with genes having known functions were validated by quantitative real-time PCR and their possible function(s) were discussed. These genes include: 2-deoxyglucose-6-phosphate phosphatase, protein kinase MK5 (AFC2) and urease, which up-regulated by 1.61, 2.39 and 4.87 fold under the water-deficit stress condition, respectively. In addition, network analysis unraveled a drought response mechanism displaying activation of the ABA signaling pathway via phosphorylation by 2-deoxyglucose-6-phosphate phosphatase and protein kinase MK5. Protein kinase MK5 was found to be a central element in the drought response network, displaying numerous interactions with RNA-splicing proteins, the sugar-mediated signaling pathway and an epigenetics response (histone phosphorylation).