Transcriptional effects of the opaque-2 mutation of Zea mays L.

During the development of maize (Zea mays L.) ears it was found possible to remove kernels at two-day intervals without disturbing the development of the remaining kernels. Using this method it was possible to examine, by RNA hybridization experiments, the zein specific mRNAs during the development of wild-type and opaque-2 kernels. The amounts of zein proteins synthesized at various developmental stages in both genotypes was shown to be strictly correlated to the amounts of zein mRNA present in the endosperm. The opaque-2 mutation resulted in reduced accumulation of the zein mRNAs, particularly those coding for the 21,000 proteins, and did not affect translation, as previously suggested. Furthermore, hybridizations of restriction endonuclease digested and electrophoretically fractionated maize DNA with zein cDNA probes showed no differences between wild-type and opaque-2 plants in the genome organization of the zein genes. It is suggested that the opaque-2 mutation acts directly upon zein gene transcription.