Table of Contents

RISK ASSESSMENT NEWS

Field-Evolved Resistance in Corn Earworm to Cry Proteins in Transgenic Corn and Its Implications
P. Dilip Venugopal and Galen P. Dively

Crops engineered with genes from the soil bacterium Bacillus thuringiensis (Bt) to express specific proteins with insecticidal properties (Cry proteins) are a major tool to manage agricultural insect pests. However, with widespread use of genetically engineered crops, insect resistance to these proteins is a major threat to the Bt technology. In this article we discuss factors contributing to the evolution of resistance in corn earworm to transgenic corn expressing Cry1Ab and Cry1A.105/Cry2Ab2 proteins. Further, we describe the implications of corn earworm resistance for resistance monitoring, regulatory policies, further research, and the sustainability of the pyramided Bt technology.

PLANT RESEARCH NEWS

CRISPR/Cas9 for Excising Chromosomal Fragments: A Viable Tool for Eliminating Marker Genes from Transgenic Plants
Vibha Srivastava

Genetic engineering involves plant cell transformation, selection, and regeneration of transgenic plants. Both conventional genetic engineering and homology-directed recombination transformation methods involve selection of the transformed events through tissue culture, and therefore, are reliant on selection marker genes (SMGs). The removal of SMGs from transgenic plants is encouraged by scientific panels and agencies regulating genetically engineered crops. We have evaluated the efficiency of using CRISPR/Cas9 to excise marker genes, and have shown that dual-targeting by CRISPR/Cas9 in rice leads to precise excision of marker gene, which can be easily detected by PCR.

Second Generation Maize Hybridization Technology Has Potential to Improve Food Security and Agricultural Sustainability
Jim Gaffney and Bo Shen

Nitrogen is often a limiting factor of maximum yield potential in maize production. It is also one of the most expensive inputs for farmers. In developing countries, a combination of highly weathered tropical soils with low organic matter, low nitrogen, and use of older open-pollinated varieties and poor quality hybrids severely limit maize productivity for smallholder farmers. Improvements in nitrogen use efficiency and hybrid seed systems will reduce further the environmental footprint of maize production while enabling continual productivity gains, especially for farmers in tropical countries.