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Molecular Plant Breeding 2010, Vol.1 No.2
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1.2 Field resistance of the improved lines to
lepidopteron insects
It is clear from table 1 that the most of the improved
9311 and Fuhui 838 lines which separately have
cry1Ac,
cry1C*
and
cry2A*
genes got excellent resistance to the
target leaffolders, and only 9311 (
cry2A*
) got a little
damage. Especially in the improved lines Fuhui 838
(LX111), Fuhui 838 (LX183) and Fuhui 838 (LX124),
there were no damaged situations in the whole growth
period. The above results bring into correspondence
with the reports (Tang et al., 2006; Chen et al.,
2005).While, the controls suffered some damage about
10 percents by the leaffolders, though the natural pests
were not too much in Wuhan of centered China in 2009.
Table 1 The damage investigation of leaf folders in the different lines
Names of progenies Genotype
Different folded leaves
Numbers of leaves/
Plants
Folded leaves (%)
None
1
-
3
3
-
5
5
-
8
Full
9311
None
√
70
10
9311(LX21)
1Ac √
70
0
9311(LX7)
1C*
√
70
0
9311(LX64)
2A*
√
70
1.5
Fuhui 838
None
√
50
10
Fuhui838 (LX111) 1Ac
√
50
0
Fuhui (LX83)
1C*
√
50
0
Fuhui 838 (LX124)
2A*
√
50
0
Note: √ means that the damaged leaves
1.3 The agronomic performance of the selected
homozygous lines
The improved homozygous lines got good performance
in the agronomic traits, and many improved lines have
more advantages than the negative controls in the
different agronomic traits, such as LX83 (Fuhui
838/
1C*
), the line got some improvements comparing
to the controls in yield related traits, such as grains per
plant, yield per plant, grains per tillers (Table 2).
2 Discussion
Rice germplasm 9311 and Fuhui 838 are two
elite parent lines widely used for two and three-line
indica
hybrid rice in China respectively; both of them
have excellent combining ability. While the
lepidopteran pests are causing increasing damages to
rice, which have negative effects to their performance.
In this study, three
Bt
genes,
cry1Ac
,
cry1C*
and
c
ry2A*
, were introgressed into 9311 and Fuhui 838.
Some new improved lines which both had excellent
resistance to the target pests and good agronomic traits
were obtained by marker-assist selection and
pheotyping assays.
It is obvious from assays of insect-resistant in the field
that the resistance of the improved lines to the target
pests got great improvement after the three
Bt
genes
were integrated into the plants. The lines with
cry1Ac
and
cry1
C* had strong resistance, whereas, the lines
with c
ry2A*
got
a little damage which would not
bring any obvious negative effects. The above results
show no differences with the previous reports (Tang
et al., 2006; Chen et al., 2005). Therefore, the three
Bt
genes could be used in the future application for
Bt
hybrid rice.
Regarding the agronomic performance, the basic
agronomic traits did not show any differences with the
controls, 9311 and Fuhui 838. In the natural
infestation, the agronomic traits of many improved
lines had some advantages comparing to the negative
controls, but some lines did not show any better
performance in many agronomic traits. As this result,
we confer that there are two followed reasons. One is
that, the weather in Wuhan, 2009 was cooler than
normal years, so the natural infestation was not severe
in Wuhan, 2009; The other is that the main harm
period of the leaffolders was after the heading stages,
and many agronomic traits, especially the yield related
traits, showed no obvious differences between the
improved lines and negative controls.