Steady‐State Polypeptide Profiles of Whorl Tissue from Lepidoptera‐Resistant and Susceptible Corn Inbred Lines

Abstract

Breeding lines of corn (Zea mays L.) with resistance to the southwestern corn borer (Diatraea grandiosella Dyar) and fall armyworm [Spodoptera frugiperda (J.E. Smith)] have been developed, yet the underlying mechanisms of the resistance have not been fully elucidated. Our objective was to determine whether qualitative differences exist in polypeptide profiles of whorl tissue from leaf.feeding‐resistant inbreds (Mp708, Mp707, Mp704, and Mp496) vs. several leaf‐feeding‐susceptible inbreds (Tx601, Ab24E, GT106, and SC229). Preliminary greenhouse studies demonstrated that the validity of such comparisons required strict matching of tissue samples for overall chlorophyll content due to shading within the whorl. Two‐dimensional gel electrophoresis of total protein extracts from tissue of field‐grown plants identified two polypeptides (36 and 21 kDa) whose presence in combination was predictive of resistance. The various susceptible inbreds contained either one or the other of the polypeptides but not both. Further work, comparing the segregation of these two polypeptides with resistance levels in progeny from crosses of resistant and susceptible inbreds, will be required to determine whether they will be generally useful as markers for this source of pest resistance.