Pearl millet is an important source of energy and nutrition for millions of people in the drylands of sub-Saharan Africa and South Asia. Recently, blast, also known as leaf spot, caused by Magnaporthe grisea (Anamorph: Pyricularia grisea) has emerged as a serious threat to pearl millet cultivation causing substantial yield loss. Seeds tend to contain several storage proteins, some have an inhibitory action against plant pathogens. The present study aimed to identify the defense proteins in seed extrudes of ten pearl millet blast differential lines and investigate their protective effect against growth of Pyricularia grisea (Pg 45, Patancheru isolate). The biochemical observations of seed extrudes revealed the presence of plant defense linked hydrolytic enzymes chitinases (12-18 units/ml), β-1,3 glucanases (16-48 units/mg protein) as well as cysteine protease inhibitors (57-123 PI units/mg protein) among the tested lines. The pre-treatment of P. grisea media with respective line seed extrudes resulted in significant reduction (22-40%; p<0.001) of fungal radial growth and fungal dry weight (20-77%; p<0.001). The effective concentration for the 50% fungal growth inhibition (EC50) was identified as 400 and 600 μg/ml for resistant lines IP 21187 and ICMR 06444, respectively. Further, the seed extrudes were able to significantly retard the spore germination (by 18 h) and initial growth (by 48 h) of Pg 45 by 24-83%. These findings suggest that the identified proteins are playing synergistic role in pearl millet defense against blast pathogen, Pg 45 and provide the basis to explore the novel biological control strategies in plant defense
