Doubled haploid (DH) technology is a
useful tool for maize breeding and gene discovery.The production of a large number of DH lines has been
possible recently with the development of various
in vivo haploid inducer lines based on the discovery of
the initial stock 6. Most of the haploid induction
systems use the R1-navajo (R1-nj) gene whose
expression in the kernel produces diploid kernels with
colored aleurone crowns and scutella and haploid
kernels with colored aleurone crowns but colorless
scutella. However, the R1-nj gene expression depends
on various genetic and environmental factors, which
can mask the typical R1-nj phenotype. To solve this
problem, we introduced a dominant green fluorescent
protein (GFP) marker gene into a maize haploid
inducer, RWS, to generate a RWS-GFP inducer. This
line allows the identification of haploids in the early
germination stage by visualizing the GFP expression
of germinated kernels.