Application of Brachypodium to the genetic improvement of wheat roots

Authors: CHOCHOIS, VINCENT - Commonwealth Scientific And Industrial Research Organisation (CSIRO); Vogel, John; WATT, MICHELLE - Commonwealth Scientific And Industrial Research Organisation (CSIRO)

Submitted to: Journal of Experimental Botany
Publication Type: Review Article
Publication Acceptance Date: 1/26/2012
Publication Date: 3/30/2012
Citation: Chochois, V., Vogel, J.P., Watt, M. 2012. Application of Brachypodium to the genetic improvement of wheat roots. Journal of Experimental Botany. 63:3467-3474.

Interpretive Summary: This paper describes the potential of the model grass Brachypodium distachyon to be used to study grass roots. The aim of such research is to develop knowledge that can be used by plant breeders to create higher yielding cultivars of cereal grains like wheat and barley. It is desirable to use a model system to study roots because of the inherent difficulties associated with studying roots due to their underground location and complex interactions with their environment. In this context it is noteworthy that due to its small size, a mature Brachypodium root system can be grown in manageable sized pots without crowding. Significantly, despite its small size, Brachypodium root architecture and development is very similar to wheat. Other advantages of Brachypodium include its small genome size, sequenced genome and a wealth of experimental resources.

Technical Abstract: This paper describes the potential of the model grass Brachypodium distachyon to be used to study grass roots. The aim of such research is to develop knowledge that can be used by plant breeders to create higher yielding cultivars of cereal grains like wheat and barley. It is desirable to use a model system to study roots because of the inherent difficulties associated with studying roots due to their underground location and complex interactions with their environment. In this context it is noteworthy that due to its small size, a mature Brachypodium root system can be grown in manageable sized pots without crowding. Significantly, despite its small size, Brachypodium root architecture and development is very similar to wheat. Other advantages of Brachypodium include its small genome size, sequenced genome and a wealth of experimental resources. To meet the demands of a larger and more affluent global population, wheat yields must double this century with less irrigation, fertilizer, and land. Modeling and experiments consistently demonstrate a large potential for increasing wheat productivity by improving root systems, however application of research to new varieties is slow because of the inherent difficulties associated with working under ground. This paper makes the case for the use of the model grass Brachypodium distachyon (Brachypodium) to simplify root research and accelerate the identification of genes underlying wheat root improvement. Brachypodium is a small temperate grass with many genomic, genetic and experimental resources that make it a tractable model plant. Brachypodium and wheat have very similar root anatomies which are distinct from rice root anatomy that is specialized to help it overcome anaerobic conditions associated with submerged roots. As a dicotyledonous plant, Arabidopsis has an even more divergent root system that features a tap root system and cambia with secondary growth, both of which are lacking in the grasses. The major advantage of Brachypodium is its small stature that allows the adult grass root system to be phenotyped. This will facilitate the identification of genes in adult roots that greatly influence yield by modulating water uptake during flowering and grain development. A summary of the advantages of Brachypodium for root studies is presented including data describing the adult root system architecture to depth and root growth during grain development. Routes to translate discoveries from Brachypodium to wheat are also discussed.