Knock-out mutants of two members of the AGL2 subfamily of MADS-box genes expressed during maize kernel development

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In search of maize MADS-box genes expressed during kernel development we identified two cDNA’s corresponding to the AGL2 MADS-box gene subfamily members ZMM6 and ZMM27. Expression analyses show that expression is restricted to developing infloresences and developing kernels. In kernels the accumulation of both transcripts increase after pollination, indicating that they play a role during kernel development. In situ hybridization revealed that ZMM27 is expressed in both maternal and zygotic kernel tissues, whereas ZMM6 expression becomes restricted to the endosperm transfer cell region and the embryo as the grain develops. In an attempt to elucidate the role of MADS-box genes expressed during maize kernel development, we identified Mutator-insertion loss-of-function alleles for both ZMM6 and ZMM27 using reverse genetics. Analyses of plants homozygous for the mutant allele of ZMM6 or ZMM27, as well as double homozygous mutants showed no obvious developmental defects in the kernel, suggesting the presence of additional members of the AGL2 clade in maize with functional redundancy with of ZMM6 or ZMM27.