Comparative Proteomic Analysis of Genotypic Variation in Germination and Early Seedling Growth of Chickpea under Suboptimal Soil–Water Conditions

Protein expression patterns in imbibed seeds of three
cultivars
of chickpea (Cicer arietinum L.) with different rates
of germination under limiting water supply in soil (>10% water
holding
capacity) were compared. A large number of soluble proteins expressed
earlier and at higher levels in cv Rupali seeds compared
to two other genotypes that germinated less rapidly (KH850) or not
at all (KJ850). Among the proteins identified were those with chaperone-like
functions, including LEA and HSP proteins and proteins involved in
metabolism of reactive oxygen species (ROS). Only NAD-malate dehydrogenase
was identified as an early, differentially abundant enzyme of the
TCA cycle, but in cv Rupali, expression of phospho-enol-pyruvate
carboxykinase rose very rapidly to a high level, indicating that an
anaplerotic C input to the TCA cycle may have been important. Proteinase
inhibitors were more highly expressed in the genotype that did not
germinate compared to cv Rupali. Clustering analysis
of proteomic data indicated a link between groups of proteins, implying
a common regulatory mechanism possibly at the transcriptional level.
The chaperone-like proteins and enzymes of ROS homeostasis provide
a useful starting point for molecular genetic analysis that may well
identify other important genes for the early germination trait.