Comparative proteomics and gene expression analysis in Arachis duranensis reveal stress response proteins associated to drought tolerance.

Peanut wild relatives (Arachis spp.) have high genetic diversity and are important sources of resistance to biotic and abiotic stresses. In this study, proteins were analyzed in root tissues of A. duranensis submitted to a progressive water deficit in soil and the differential abundance was compared to transcript expression profiles obtained by RNA-seq and qRT-PCR. Using a 2-DE approach, a total of 31 proteins were identified, most of which were associated with stress response and drought perception. These comprised a chitinase-2 (unique to stressed condition), an MLP-like protein, a glycine-rich protein DOT1-like, a maturase K and heat shock-related proteins (HSP70 - an isoform unique to the control, and HSP17.3). Other proteins unique to the control condition comprised a transcription initiation factor IIF subunit alpha-like protein, a SRPBCC ligand-binding domain superfamily protein, an Adenine phosphoribosyl transferase, a Leo1-like protein, a Cobalamine-independent methionine synthase and a Transmembrane emp24 domain-containing protein p24delta9-like. Correlation of mRNA expression and corresponding protein abundance was observed for 15 of the identified proteins, with genes encoding the majority of proteins (14) negatively regulated in stressed roots. Proteins identified in this study offer potential for the genetic improvement of cultivated peanut for drought tolerance. SIGNIFICANCE: The comparison of protein abundance and corresponding transcript expression levels (RNA-seq and qRT-PCR) revealed that 15 of the identified proteins showed similar expression behavior, with the majority (14 proteins) negatively regulated in stressed roots. Chitinase-2 (Cht2) was the only protein with an upregulation behavior in all approaches. These proteins appear to play an important role in drought tolerance in A. duranensis and may be further explored in peanut genetic breeding programs.