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Table 2.
Seed settings in different mutants grown under LD condition.
The WT-like phenotype displayed by myb24-t1 and myb57-t1 and mild floral
phenotype displayed by myb21-t1 suggest that these MYB genes might function
redundantly during stamen development. To prove this hypothesis, crosses were
made among homozygous myb24-t1, myb21-t1 and myb57-t1 plants. Three dou-
ble mutants (myb21-t1 myb24-t1, myb21-t1 myb57-t1, and myb24-t1 myb57-
t1) and one triple mutant (myb21-t1 myb24-t1 myb57-t1) were generated and
used in our phenotypic analysis.
The flower development of myb24-t1 myb57-t1 double mutant at all stages
was indistinguishable from the WT control (Figure 3D; Table 2) [1]. Stamens
in mature flowers of the myb21-t1 myb24-t1 double mutant were shorter than
that of the myb21-t1 single mutant and shorter stamens were also observed in
majority of the late developed mature flowers in the double mutant. As a result,
the myb21-t1 myb24-t1 double mutant is more severely sterile than myb21-t1 by
having fewer siliques with seed settings (Figure 3C and 3D; Table 2), an observa-
tion also reported by Mandaokar et al [32]. The myb21-t1 myb57-t1 double mu-
tant had shorter stamens in early developed mature flowers and some of the later
flowers (Figure 3D) and its seed settings displayed an intermediate phenotype
between myb21-t1 single and myb21-t1 myb24-t1 double mutants (Figure 3C
and 3D; Table 2). Interestingly, cross-pollination showed that the short stamens
in both myb24-t1 myb21-t1 and myb21-t1 myb57-t1 double mutant plants pro-
duced viable pollens (data not shown), suggesting that the short stamen is respon-
sible for the reduced fertility in these mutants.
The myb21-t1 myb24-t1 myb57-t1 triple mutant, as the myb21-t1 myb24-t1
double mutant, had short stamens but was even more severely sterile than myb21-
t1 myb24-t1 (Figure 3C and 3D; Table 2). For myb21-t1 myb24-t1 double and
myb21-t1 myb24-t1 myb57-t1 triple mutant plants, we occasionally observed
