Comparative Proteomic Analysis for Identification and Characterization of Nutritionally and Stress-responsive Seed Proteins of Finger Millet with Respect to Rice

In the present investigation, we compared the seed proteome of finger millet (Eleusine coracana L. Gaertn) and rice to gain an insight about the nutritional and stress-related proteins accumulated during finger millet seed development. Seed proteins of finger millet and rice were analyzed using Liquid Chromatography-Mass Spectrometry/Mass Spectrometry (LC-MS/MS) and a total of 453 and 437 proteins were identified respectively. Comparative analysis revealed 25 and 9 proteins unique to finger millet and rice, respectively. Out of these unique proteins, 17 amd 5 were seed storage proteins (SSPs). In finger millet, these SSPs were the gliadins, zeins, and avenins. The rest of the unique proteins in both crops were the proteins involved in abiotic and biotic stress tolerance. Of the 428 common proteins, the relative abundance of 175 proteins was higher in finger millet. Twenty proteins of this list were SSPs which largely consisted of the proteins belonging to the prolamin protein family. However, only one 63 kDa globulin protein showed an exceptional accumulation of about 244-fold in rice seeds compared to finger millet. Further, a Late Embryogenic Abundant (LEA) protein along with several stress-related proteins such as amylase/trypsin inhibitors, defensins, and oleosins were identified that accumulated highly in finger millet seeds. Furthermore, five EF (Elongation factor) hands containing calcium-dependent protein kinase (CDPK) were also identified as highly expressed in finger millet compared to rice. The present investigation would expand our knowledge in understanding the biosynthetic pathways involved in nutritional partitioning during seed development.