Transcriptomic analysis of aerial and root organs in two apple tree cultivars under soil water deprivation
Climate change, especially drought, provokes irregularities in fruit tree production. This context urges to select new cultivars adapted to drought conditions, with conservation of the valuable agronomic traits. The present study focuses on the identification of apple tree cellular and metabolic responses to soil water deprivation. Two apple cultivars ('Starkrimson' and 'Granny Smith') were grown either in well-watered (WW) or under soil water stress (WS) to reach 50% of FTSW. On two plants per genotype, apex, leaf and root samples were collected and RNA extracted. AryANE micro-array apple chip was used to analyze the transcriptome. Among genes differentially expressed between WW and WS and common to cultivars and organs, roots expressed the highest amount of up and down regulated genes in comparison to leaves and apex. The perception of drought stress by roots triggered ABA-dependent pathway which induced the expression of signal transduction and transcription factors (TFs) involved in the crosstalk between stress signaling pathways, e.g., ABA insensitive (ABI) and homologous to ABI (HAB) families, members of Basic-leucine zipper (e.g., AREB/ABF) family. All these TFs trigger a cascade of stress response genes expressing under WS such as members of responsive to desiccation (RD22, RD29B, RD26). ABA biosynthesis pathway was highly induced by WS by gene activation of several key enzymes: NCED, CCD, ZEP, VDE, SDR, which catalyze the major regulatory steps of ABA biosynthesis which are highly promoted especially in the roots; CYP707A involved in the ABA cleavage, was also activated. These pathways, highly conserved among plants, will be confronted to previously detected QTLs in a segregating population issuing from the two studied genotypes as parents, for defining candidate genes.
Krichen, L., Guitton, B., Kelner, J.J. and Costes, E. 2017. Transcriptomic analysis of aerial and root organs in two apple tree cultivars under soil water deprivation. Acta Hort. (ISHS) 1172:283-288
ABA signaling, transcriptome, Malus × domestica, water stress