Biology Reference
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Table 2.
Morphometric measurements of seeds correlated to BASTA R as reported in
Loss of MET1 During Female Gametogenesis does not Impact
on Seed Size
While crosses between wild type ovules and the MET1a/s pollen caused a de-
crease of seed size, a symmetrical increase of seed size was observed in seeds from
the reciprocal crosses MET1a/s×wt. [7]-[9]. We tested whether maternal inheri-
tance of met1-3 from met1-3/+ mothers would increase size in 50% of the seeds.
Crosses between ovules from met1-3/+ plants and wild-type pollen did exhibit
increased seed size relative to wild type controls (Figure 1A; n = 900) correlated
with an increased in endosperm size. However, this increase in size affected the
whole population of seeds (Figure 1D, Table 1, n = 138). Largest seeds selected by
visual inspection from a population of 900 seeds from wt×met1-3/+ crosses did
not show a preferential resistance to BASTA (55.1% BASTA Resistant in a popu-
lation of n = 84 largest seeds). This is contrary to the expected consequence of a
maternal gametophytic effect of met1-3/+, which should produce a greater pro-
portion BASTA resistance among the largest seeds in a population derived from
met1-3/+×wt crosses. To confirm this finding we compared BASTA resistance and
seed size in an entire population of seeds from met1-3/+×wt crosses from a single
plant. We observed that larger seeds did not always inherit the met1-3 allele and
the means of size measurements did not differ between seed genotypes (Figure 2B,
Table 2). These results were in clear contrast to the results obtained from crosses
involving pollen from met1-3/+ plants. The inheritance of met1-3 from met1-3/+
plants through the female gametes did not cause the increase of size in 50% of
the seed population as expected for a gametophytic maternal effect. However we
observed an overall increase of seed size in the entire population of seeds (Fig. 1D,
Table 1). Thus, it was possible that either the gametophytic effect was not fully
penetrant and could not be detected clearly. Alternatively it was possible that the
maternal effect of met1 was mediated from the maternal tissues surrounding the
seed.
