VIEW ARTICLE

Molecular Plant Pathology

Detection and Partial Characterization of New Polypeptides in Peanut Cotyledons Associated with Early Stages of Infection by Aspergillus spp.. J. B. Szerszen, Department of Plant Pathology and Microbiology, Texas Agricultural Experiment Station, Texas A&M University, College Station 77843; R. E. Pettit, Department of Plant Pathology and Microbiology, Texas Agricultural Experiment Station, Texas A&M University, College Station 77843. Phytopathology 80:1432-1438. Accepted for publication 8 May 1990. Copyright 1990 The American Phytopathological Society. DOI: 10.1094/Phyto-80-1432.

Polypeptide profiles of peanut cotyledonary tissue from viable kernels of 14 cultivars grown under normal irrigation and five genotypes grown under drought stress were determined before and after invasion by Aspergillus flavus and A. parasiticus. Inoculated kernels and isolated cotyledons were removed from moist chambers every 6 hr within 48 hr after inoculation. Polypeptide patterns were determined by microprocessor-controlled sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and two-dimensional electrophoresis and visualized after staining with silver. Uninoculated cotyledonary tissue contained 35 comigrating groups of SDS-dissociated proteins (13.5?218.7 kDa), and mapping showed the presence of 257 components within pI range 3.00?8.70. Four new polypeptides (16.4, 18.1, 23.0, and 30.6 kDa; pI 7.95, 8.00, 7.90, and 7.55, respectively) were present in viable intact kernels and live, isolated cotyledons 18?24 hr following inoculation. Two additional polypeptides (19.9 and 22.0 kDa; pI 8.15 and 8.00, respectively) were detected after 24?30 hr of incubation in cotyledons from plants grown under normal irrigation. Drought stress inhibited the synthesis of these polypeptides except in kernels of cultivar TX 798736, which contained five of them, including one specific for this cultivar (37.2 kDa; pI 6.50). Mapping of polypeptides showed their enhanced synthesis with time and variations in amounts among cultivars tested.