Endorsperm Development of Maize Defective Kernel (dek) Mutants. Auxin and Cytokinin Levels

To provide insight into the regulatory roles of auxin and cytokininin endosperm development, defective kernel (dek) mutants ofmaize (Zea mays L.) were examined. The mutants dek6, dek18 anddek 26 had substantially lower indole-3-acetic acid (IAA) levelsthan wild-type counterparts while dek8, dek12 dek24 had higherIAA levels than wild-type counterparts. The mutant dek6 hada somewhat lower zeatin level than its wild-type counterpart.The mutation-induced changes in IAA levels and effects of exogenously-appliedauxin were not consistently related to changes in numbers ofnuclei per endorsperm; however, there was a correspondence betweenauxin level in endosperm and nuclear diameter, which is proportionalto the extent of post-mitotic DNA synthesis (endoreduplication).We conclude that auxin may be involved in stimulating endoreduplication.Copyright1993, 1999 Academic Press Zea mays L., maize, defective kernel mutant, dek, auxin, cytokinin, hormone, ELISA, cell number, cell division, endopolyploidy, endoreduplication, DNA amplification