3.4. Activities of AGP, SSS, BE, and DBE
The activity of AGP increased gradually from 0 DAF to 15 DAF
and then began to decrease; however, this enzyme retained some
activity until 25 DAF. The increasing rate found for MR4 was lower
than that obtained for the other two mutants. The activity of AGP
in MR7 was the highest, whereas that of the AGP in MR4 was the
lowest throughout the grain development process. Especially at
10 DAF and 15 DAF, the activities of AGP were significantly different
among MR1, MR7 and MR4 (Fig. 4A), the activities of AGP
exhibited a slightly negative correlation to the AAC and RS content
and a positive correlation to the grain weights (Fig. 1).
Similarly, the activities of SSS reached a maximum at 10 DAF and
then decreased gradually. MR4 exhibited the highest SSS activities at
5 DAF, and no significant differences were observed among the three
materials after 15 DAF (Fig. 4B). MR1 exhibited a higher BE activity
than MR4 before 15 DAF, and there were no clear differences in the
BE activities after 15 DAF. While after 15 DAF, the activities of BE
in MR1 and MR4 were significant lower than those found in MR7
(Fig. 4C). The SSS activity negatively affected the RS content slightly
while no correlations between BE and RS were found (Fig. 1).
The activity of DBE increased rapidly from 5 DAF to 10 DAF and
then decreased gradually. The DBE activity were significantly different
among the three material after 10 DAF and the activity of
DBE in MR4 was the highest and remained at a medium level until
25 DAF (Fig. 4D). In addition, this activity showed positive correlations
to the RS content and the AAC (Fig. 1).