Iowa State University
Isolation of the new recessive mutant lrt1 deficient in lateral root
--Hochholdinger, F; Schnable, P; Feix, G
The root system of maize consists of embryogenic primary-
and seminal lateral, and postembryonic crown- and brace roots.
All of these root types form lateral roots from the pericycle cell
layer. A mutant deficient in the formation of lateral roots
(designated lrt1 for lateral-rootless1) has been identified in a
seedling screen of segregating M2 families derived from an EMS
mutagenized B73 population (established in 1994 in Ames). This
recessive mutant is completely deficient in lateral root formation
on early forming roots as evident from the comparison of
14-day-old wild-type and mutant seedlings shown in the figure.
Mutant plants grow slower and are of smaller size than
corresponding wild-type plants, but are, however, still fertile.
Histological analysis of sections from 14-days-old primary
roots of wild-type and mutant plants revealed that, in contrast to
the large number of lateral roots already formed at that stage in
wild-type plants, only a few lateral root primordia had formed in
the primary root of mutant plants. Further, in mutant seedlings
none of these primordia had grown out to form lateral roots. An
equal number of such rudimentary primordia were also found in the
primary root of 14-day-old wild-type plants. Hence, the
relationship between these rudimentary primordia and the lrt1
gene remains to be elucidated
Further characterization of this new mutant, including
investigations at later stages of development and hormone action
studies, are in progress.
Figure. The root system of two 14 day old wt plants (left) in comparison to two lrt1 plants
(right), lacking lateral roots.
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