Localization of soluble and insoluble fractions of hydroxyproline-rich glycoproteins during maize kernel development

Monoclonal antibodies have been developed against PC-1 protein, the major hydroxyproline-rich glycoprotein (HRGP) from maize pericarp, and have been used as probes in an indirect alkaline phosphatase antibody assay to localize this protein in tissue of three maize varieties. Kernels were sampled several days after pollination (d.a.p.). HRGPs were assayed by reacting antibodies with tissue prints of kernels and embedded tissue samples. Tissue prints show that soluble HRGPs are present in small quantities even at early stages of kernel development The greatest accumulation of PC-1 in the pericarp is at the top of the kernel. As the kernels mature, HRGPs begin to accumulate in the developing embryo. Total HRGPs in embedded tissue begin to accumulate at 10 d.a.p. and increase quite dramatically at 20-30 d.a.p. Popcorn kernels lose antigenic reactivity at 40 d.a.p., while sweet corn kernels continue to show strong reactivity.