Large scale comparative proteomics analysis of genotypic variation in germination and early seedling growth of chickpea under sub-optimal soil water conditions

The research of this thesis has applied a proteomic approach to identifying proteins associated with more rapid germination of chickpea (Cicer arietinum L.) seeds under limiting water supply in soil. A method was developed so that different genotypes could be compared under strictly controlled environmental conditions such that water supply could be reproducibly applied at levels less that 10% water holding capacity in a sand medium. A number of very similar genotypes were grown for seed under the same field conditions in the same season and the harvested mature seed graded for size, regular shape, color and weight. Seeds of the same grade and size were compared across genotypes. The levels of water were established without the use of poly ethylene glycol (PEG) or other additions such that the levels chosen resulted in very different rates of radicle emergence among the genotypes. The assay developed in the study determined that seed size is an effective variable for germination performance, particularly at extremely decreased water levels. Despite the lack of any physical barrier for seed water absorption, germination rate and further radicle growth also varied significantly among chickpea genotypes. The proteins were extracted at imbibition (0 hr) and at 48 and 72 hr after imbibition, separated on 2DE-Gels using narrow pH range isoelectric strips (pH 4-7) to gain excellent resolution of up to 760 Coomassie blue-stained spots. Those spots that were differentially abundant across genotypes and sampling times were determined using PDQuest software, excised, and after digestion analyzed by MALDI-TOF/TOF MS/MS.