mutants do not respond to vernalization in short
and van der Veen (1980) and
Wilson et al. (1992) were the first to notice that
ga1-3 mutants are insensitive to
in short days, and concluded that there was some
connection between the two pathways. However,
this hypothesis vas invalidated
(Michaels and Amasino, 1999;
Chandler et al., 2000).
... But their ability
to respond to vernalization is not affected:
In long days, the
ga1-3 mutants expressing both FRI
and FLC functional alleles, as well as ga1-3
mutants expressing FCA, do respond to
et al., 1992).
Michaels and Amasino (1999)
analyzed the possible interactions between these
2 pathways, observing flowering time in three
In 8h days (short days),
vernalization accelerates flowering in the WT,
but does not make ga1-3 mutants able to flower.
In 10h days, the WT
flowering time is very similar to what it is in
short days, with or without vernalization.
However, the ga1-3 mutants do indeed respond to
vernalization: they flower when they are vernalized, whereas they still do not flower if
they are not vernalized.
In 16h days (long
days), both the WT
and ga1-3 respond to vernalization, which
accelerates flowering by a similar number of
days in both genotypes.
investigate the response to vernalization, the
authors studied the flowering time in La-er
ecotypes introgressed with functional alleles of
FRI and FLC (These
plants were therefore fully sensitive to
vernalization). They found that, in both WT and
ga1-3 backgrounds, there is a strong response to
vernalization. Therefore, the ga1-3 mutation does not alter
the ability to respond to vernalization.
promote flowering through independent pathways:
connection between the GA and vernalization pathways
was also investigated by
Chandler et al. (2000).
However, these experiments were done in 10h-long
days, in which the ga1-3 mutants do flower,
albeit very late. In these experiments, ga1-3 is
late-flowering and not affected by
vernalization. However, the WT is not much
affected either. The fca-1 mutant responds
strongly to vernalization, and the double mutant
fca-1 ga1-3 also responds to vernalization and
flowers at the same time as the ga1-3 single mutant.
This means that, when ga1-3 is in a
vernalization-sensitive background (such as
fca-1), it does respond strongly to
vernalization. The conclusion is that
the GA pathway does not interact with the