After herbicide resistance in major crop species, the first target area for GM crop development was that of protection against plant pests.283 Although tolerance of modern herbicides is usually located in the amino acid sequences of a handful of target genes in biosynthetic pathways, plants have multiple inducible mechanisms to fight back against microbial pathogens:284 [44]

Wheat is prone to attack by the rust pathogens, Puccinia graminis and P. tritici; stem and leaf rusts are considered to be major constraints to wheat production world­wide.285 More immediately alarming from the perspective of Iogen’s dependence on wheat biomass is that new and highly infectious variants of the pathogen have been noted in Africa for some years, with newspaper reports in the first quarter of 2007 describing its spread into Asia. A single gene (Sr2) has been identified as a broad — spectrum resistance locus for more than 80 years; recently, this gene (or two tightly linked genes) confer resistance and the associated dark pigmentation traits, pseudo­black chaff.286 Stem rust-susceptible barley has been transformed into a resistant form by an Agrobacterium plasmid containing the barley resistance gene, RpgP; a single copy of the gene is sufficient to confer resistance against stem rust.287

Of the abiotic stresses that plants experience, drought is a serious limiting factor on growth and productivity even in the Northern Hemisphere, and cereal crops are highly prone to fluctuating yield depending on seasonal rainfall and average tempera­tures in the growing season; to be dependent on a monoculture crop such as wheat (for starch or straw) runs the risk of uncertain prices as well as variable feedstock availability. With the evolution of domesticated cereal species over millennia, genetic diversity has been lost; using the natural genetic diversity of wild species is an invalu­able resource because wild types harbor very broad ranges of tolerance characteris­tics; other exploitable traits include those for salt tolerance (allowing saline water to be the source of irrigation) and, especially if global temperatures increase because of global warming, flowering times and other growth parameters more typical of Medi­terranean regions for transfer to cultivars grown further north.288 Drought appears to exert physiological effects via oxidative stress signaling pathways, a property shared with freezing, heat, and salinity stresses; protein kinases are often associated with signaling pathways and expression of a protein kinase gene (NPK1) from tobacco in maize protects kernel weights when the water supply is reduced.289