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March, 2007
Plant
Breeding
Volume 126 Issue 2 Page 169 - April 2007
Heterosis in yield, endotoxin expression and some
physiological parameters in Bt transgenic cotton
H. Z. Dong, W. J. Li, W. Tang, Z. H. Li, D. M. Zhang (2007)
Plant Breeding 126 (2), 169–175.
doi:10.1111/j.1439-0523.2007.01321.x
ABSTRACT
Although heterosis in cotton has
been studied for many decades, very little is known about the
performance of hybrids derived from Bt transgenic cotton
parents. In order to known better the heterosis performance,
yield and endotoxin expression in 20 hybrids (F1) and their Bt
transgenic parents were examined from 2002 to 2003 (Experiment
1), and the dynamics of source, sink and their ratios in a
well-performing hybrid H01 were investigated in 2004 and 2005
(Experiment 2). Results in Experiment 1 showed an average
mid-parent heterosis of 21.3% and an over check heterosis of
7.6% in lint yield. Considerable heterosis was also detected in
boll numbers, boll size and Bt protein content. Of the 20
hybrids, H01 (K0215 × K643) exhibited the greatest heterosis in
yield and Bt protein content in 2002 and 2003, while lint yields
of H01 were increased 12.6% and 9.1% in 2004, and 11.7% and 8.9%
in 2005, compared with K0215 and K643 in Experiment 2,
respectively. Significant heterosis for dry matter accumulation
and dry matter allocation to reproductive organs and ratio of
fruiting forms/total plant (w/w) were also detected in H01.
Sources (leaf area, leaf area index, leaf dry weight per plant
and diurnal performance of photosynthesis), sinks (number of
fruiting nodes, fruiting forms and dry weight of fruiting forms
per plant) and the flow from source to sink were significantly
enhanced in H01 relative to its parents. Both total N and Bt
protein in H01 were higher than those in its parents.
Significant correlation was also found between total N and Bt
protein in the main-stem leaves (R2 = 0.877**). It is concluded
that there existed considerable heterosis in yield, yield
components and endotoxin expression in some Bt transgenic
hybrids. Yield advantage of hybrid cotton (F1) over parents can
be attributed to improved source, sink and flow, while the
enforced expression of Bt genes in hybrid cotton appeared to be
due to the enhanced nitrogen level in plants.
RELATED ARTICLE
Source:
CropBiotech Update
Heterosis in Bt
cotton hybrids analyzed
In two separate experiments
conducted by Chinese researchers, hybrids derived from Bt cotton
parents showed increased heterosis in many characters. This
means that hybrids from Bt transgenic cotton parents maybe
valuable for commercial utilization.
The experiments, conducted in Shandong Cotton Research Center in
China, utilized four commercial Bt cotton varieties as male
parents and five commercial varieties as female parents. The
mid-parent heterosis observed in the Bt cotton hybrids was 21.3%
in lint yield. There are also considerable heterosis detected in
boll numbers, boll size and Bt protein content.
The researchers believe that the enhanced endotoxin expression
in terms of Bt protein concentration in Bt hybrids is due to
over-expression of heterozygous transgenes - Bt genes that are
in different chromosomes of the hybrids. The heterosis in other
characters was also explained to be influenced by the increased
leaf area and the improved flow capacity of photosynthates at
late stage of growth and development of the hybrids.
Source:
http://www.blackwell-synergy.com/doi/abs/10.1111/j.1439-0523.2007.01321.x.
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