Glyphosate resistant crops have been widely adopted by North and South
American farmers. However, the adoption of glyphosate resistant crops in
China has been hampered by several factors, including labor markets and the
residual effects of glyphosate in transgenic plants.

Chengzhen Liang from the Chinese Academy of Agricultural Sciences reported
the co-expression of codon-optimized forms of GR79 EPSPS and
N-acetyltransferase (GAT) genes in cotton. Two co-expression cotton lines,
GGCO2 and GGCO5, exhibited five times more resistance to glyphosate with a
10-fold reduction in glyphosate residues.

The GGCO2 line was then used in a hybridization program to develop new
glyphosate resistant cotton varieties. Field trials consisted of three
growing seasons showed that pGR79-pGAT transgenic cotton lines had the same
agronomic performance as conventional varieties, but were cheaper to produce
per hectare.

The strategy to pyramid these genes offers an attractive approach for
engineering and breeding of highly resistant low-glyphosate-residue cotton
varieties.



[onlinelibrary.wiley.com]