Comparative Quantitative Proteomics Analysis of the ABA Response of Roots of Drought-Sensitive and Drought-Tolerant Wheat Varieties Identifies Proteomic Signatures of Drought Adaptability

Wheat
is one of the most highly cultivated cereals in the world.
Like other cultivated crops, wheat production is significantly affected
by abiotic stresses such as drought. Multiple wheat varieties suitable
for different geographical regions of the world have been developed
that are adapted to different environmental conditions; however, the
molecular basis of such adaptations remains unknown in most cases.
We have compared the quantitative proteomics profile of the roots
of two different wheat varieties, Nesser (drought-tolerant) and Opata
(drought-sensitive), in the absence and presence of abscisic acid
(ABA, as a proxy for drought). A labeling LC-based quantitative proteomics
approach using iTRAQ was applied to elucidate the changes in protein
abundance levels. Quantitative differences in protein levels were
analyzed for the evaluation of inherent differences between the two
varieties as well as the overall and variety-specific effect of ABA
on the root proteome. This study reveals the most elaborate ABA-responsive
root proteome identified to date in wheat. A large number of proteins
exhibited inherently different expression levels between Nesser and
Opata. Additionally, significantly higher numbers of proteins were
ABA-responsive in Nesser roots compared with Opata roots. Furthermore,
several proteins showed variety-specific regulation by ABA, suggesting
their role in drought adaptation.