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For many crops, yield is the primary trait in breeding programs. Yet, till recently, the understanding of yield at the molecular level has been very limited. Probably the most important reason for this lack of the molecular understanding of yield is the difficulties to investigate yield in model organisms such as Arabidopsis, and in the lab or greenhouse environment that is available to most plant molecular biologists. Also, experimental systems that have contributed greatly to the molecular understanding of many biological processes in plants have been of little aid in the study of yield. For example, reverse genetics approaches rely on specific screens for either loss or gain-of-function phenotypes in a particular trait of interest. In the case of yield, loss-of-function would be manifested as growth deficiency, a phenotype that is obviously shared by all essential genes, whether or not directly involved in yield. Gain-of-function would be visible by a yield improvement. Yet, the relative yield increase that may be expected in such a case is probably below the detection/resolution limit of the experimental systems used by plant molecular biologists. Also, plant growth and the contribution of plant growth to harvestable yield are continuous processes, which makes it more difficult to apply time-course based transcriptome and proteome analyses.
Driven by the profound conviction that 'yield-enhancement' genes do exist in plants, CropDesign has built a platform that should lead to the identification of such genes. This platform was named TraitMillTM, and it uses rice as a model plant, rather than Arabidopsis. Amongst the world most important staple food are cereals such as rice, wheat and corn, and there is little doubt that rice will function as a much better model for studying yield in cereals than a dicot plant such as Arabidopsis. Furthermore, as for Arabidopsis, the full genome sequence of rice is publicly available, thus greatly facilitating the cloning and classification of genes and gene families. And while, in contrast to Arabidopsis, the genetic transformation of rice still requires a tissue culture step (which adds considerable complexity to the study of a quantitative trait such as yield, see further), transformation efficiency is in general higher than for other cereal crops.
To enable the identification of 'yield-enhancement'genes, the TraitMillTM platform needs to meet a few...