Corngrass1 of maize (Zea mays L) delays development of adult plant resistance to common rust (Puccinia sorghi Schw) and European corn borer (Ostrinia nubilalis hubner)

Based on morphological evidence, researchers have proposed that Corngrass1 (Cg1) of maize (Zea mays L.) is a heterochronic mutation that prolongs the juvenile-vegetative phase because distal tissues display juvenile traits that normally occur only basally, Physiological or biochemical evidence in support of this hypothesis is lacking, Disease and insect resistance often depends on physiological, biochemical, and morphological factors and can vary during ontogeny, We evaluated resistance to common rust (Puccinia sorghi Schw,) and European corn borer (Ostrinia nubilalis Hubner) in cg1 and wild-type segregating families in order to test the hypothesis that Cg1 is a heterochronic mutation that extends the juvenile-vegetative phase, In backgrounds with high expression, Cg1 mid-whorl leaves had similar resistance as Cg1 and wild-type seedling leaves, whereas wild-type mid-whorl leaves differed in resistance from the other three leaf types, In the Mo17 background, which has reduced Cg1 expression, Cg1 mid-whorl leaves had resistance levels intermediate between wild-type seedling and mid-whorl levels, These results support the hypothesis that Cg1 prolongs the juvenile-vegetative phase and suggest that heterochrony may be among the factors responsible for disease and insect resistance in normal populations of maize.