The mutant cp*-1379A, also on 3L but not allelic to dek17, is blocked early in embryogenesis. By 12 dap, mutant embryos were lagging behind normal embryos on the same ear. Normal embryos were at a late transition stage while mutant embryos had not progressed beyond an early proembryo stage. At 18 dap mutant embryos reached a mid-transition stage and did not proceed beyond this with regard to formation of a coleoptilar ring or a shoot apical meristem, morphological features characteristic of the coleoptilar stage. Mutant embryos did become broadened so as to become uniformly shell-like in appearance. Because the mutant embryos lacked shoot meristems and leaf primordia they were unable to germinate at maturity.
The mutant dscptd*-1425A, located on chromosome arm 6L, is also disturbed early in embryogenesis. Mutant embryos lagged behind normal embryos in their development by 18 dap when normal embryos were at stage 1 while mutant embryos were at a mid-transition stage. By 32 dap normal embryos were at stage 4 while the mutant embryos varied in their progression so that they ranged from a late transition to an abnormal coleoptilar stage. None of the mutant embryos ever formed leaf primordia by kernel maturity and all were abnormal in appearance. Because the mutant embryos lacked leaf primordia they were unable to germinate at maturity.
Mutant dek17 embryos could not
be distinguished from normal embryos until 18 dap. At this age, mutant
embryos were at an abnormal late transition stage and normal embryos were
at the coleoptilar stage. Mutant embryos continued to develop at a much
slower rate than normal embryos; at 45 dap mutant embryos had formed a
shoot apical meristem, a root meristem, a coleoptile, and one leaf primordium
whereas normal embryos were at stage 5 (5 leaf primordia formed). Despite
the presence of at least one leaf primordium, mutant embryos were unable
to germinate at kernel maturity. The pleiotropism of this mutation results
in a collapsed endosperm, a much delayed but otherwise essentially normal
embryo morphogenesis, and a blockage to the escape of the embryo from dormancy.
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