Identification of Water Use Efficiency Related Genes in 'Garnem' Almond-peach Rootstock Using Time-course Transcriptome Analysis

Drought is one of the main abiotic stresses with far-reaching ecological and socioeconomic impacts, especially in perennial food crops such as Prunus. There is an urgent need to identify drought resilient rootstocks that can adapt to changes in water availability. In this study, we tested the hypothesis that PEG-induced water limitation stress will simulate drought conditions and drought-related genes, including transcription factors (TFs), will be differentially expressed in response to this stress. 'Garnem' genotype, an almond × peach hybrid [P. amygdalus Batsch, syn P. dulcis (Mill.) x P. persica (L.) Batsch] was exposed to PEG-6000 solution, and a time-course transcriptome analysis of drought-stressed roots was performed at 0, 2 and 24 h time points post-stress. Transcriptome analysis resulted in the identification of 12,693 unique differentially expressed contigs (DECs) at the 2 h time point, and 7,705 unique DECs at the 24 h time point after initiation of the drought treatment. Interestingly, three drought-induced genes, directly related to water use efficiency (WUE) namely, ERF023 TF; LRR receptor-like serine/threonine-kinase ERECTA; and NF-YB3 TF, were found induced under stress. The RNAseq results were validated with quantitative RT-PCR analysis of eighteen randomly selected differentially expressed contigs (DECs). Pathway analysis in the present study provides valuable information regarding metabolic events that occur during stress-induced signalling in 'Garnem' roots. This information is expected to be useful in understanding the potential mechanisms underlying drought stress responses and drought adaptation strategies in Prunus species.