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Bioscience Methods 2012, Vol.3, No.4, 27
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After 5 days later, the bottom of the root segment and
the edges of cotyledon and leaf appeared callus tissues
in various degrees. It was found that the color of
cotyledon callus had more green and more compact,
and the callus tissue from stem segments was looser
than that from cotyledon, there were some white
clustering sticks occurring at the top of the stem
segments. Continuing to culture other 2 or 5 days, the
callus edges of the cotyledons, leaves and stems
generated adventitious buds, but not for the root
segments that were serious browning. In comparison
of several explants, the differentiation rate for the
cotyledons can reach 83.5%. Stem segments followed
by 77.0% (Table 3; Figure 1D).
Table 3 Effects of different kinds of explants on induction of adventitious buds
Explants
No. of explants
No. of callus induction
Ratio of callus
induction (%)
No. of buds induction
Ratio of buds induction
(%)
Leaf
Cotyledon
Stem
Root
20
20
20
20
12.7
18.4
16.5
3.2
63.5±0.21cC
92.3±0.48aA
82.5±0.13bB
16.3±0.76dD
9.7
16.7
15.4
0
48.5±0.24cC
83.5±0.56aA
77.0±0.37bB
0.0
1.4 The effects of the different parts of cotyledon
on morphogenesis
The whole cotyledon was cut into three segments (tip,
middle and end) as different explants that were placed
on the same medium for inducing callus. After
seven day culturing, it can see the tip explants were
beginning to appearing signs of turning yellowish, a
few of the middle and the end explants appeared
yellowing; while the callus tissues appeared on the tip,
middle and end of cotyledons in the different extent.
After 10 days later, the outer edge of the explant callus
tissues generate the adventitious buds. Statistical
analysis showed that the differentiation rates of the
middle and the end reached 100%, but the number of
induced buds of the middle segment was ar best,
followed bu the end segements (Table 4). It had a
suggestion that the part of cutting wound in explant
would be easy to induce callus and adventitious buds,
the middle segment of cotyledons would be the best
explant to induce differentiation of tomato buds.
1.5 The effects of cotyledons placing ways on the
bud differentiation
The middle segment of the cotyledon placed on the
bud inducing medium by two different ways, face
up and back up. The face-up explants were going to
be serious yellowish, but the back-up explants grew
well after one week later. The edge of callus induced
from the back-up explants occured lots of the
adventitious buds (Table 5) while the face-up cotyledons
induced only a few buds. It is obvious that under the
same conditions, the the way of the back-up placing
should be more conducive to the induction of
adventitious buds.
Table 4 Effects of different cotyledon part on induction of adventitious buds
Cotyledon part
No. of explants
No. of callus induction Ratio of callus induction
(%)
No. of buds induction Ratio of buds
induction (%)
Leaf apex
Inter part
Leaf base
20
20
20
16.7
20.0
20.0
83.5±0.35bB
100.0±0.00aA
100.0±0.00aA
16.5
20.0
20.0
82.5±0.12bB
100.0±0.00aA
100.0±0.00aA
Table 5 Effects of different way of placement on induction of adventitious buds
Placement way
No. of explants
No. of callus induction Ratio of callus
induction (%)
No. of buds
induction
Ratio of buds
induction (%)
Face up
Face down
20
20
12.3
20.0
61.5±0.63bB
100.0±0.00aA
11.8
20.0
59.0±0.48bB
100.0±0.00aA