Manipulating Stature in Biofuel Crops
Using genetic information from Arabidopsis to increase yield in biofuel crops
Project Investigator: Michael Neff, WSU
January, 2008 Progress Report
We use Arabidopsis, an easy-to-grow plant with a fully sequenced genome, to better understand how plants use light as a source of information and how the signaling pathways activated by light interact with plant hormone pathways to influence a plant’s height. With regard to the brassinosteroid hormones, we know that elevating levels of these hormones in Arabidopsis leads to larger plants with larger fruits. Reducing levels of these hormones in rice generates semi-dwarf plants with increased seed yields, possibly by changing the leaf angle and reducing lodging. We have identified enzymes in Arabidopsis and rice that can be manipulated to increase or decrease levels of these hormones. However, we have not yet identified similar genes in wheat, barley and Camelina, the first two being targets for cellulosic ethanol feed stock and the latter a potential source of biodiesel.
We have identified candidate genes from wheat and barley. These will be over-expressed in Arabidopsis to identify those which are involved in modulating levels of brassinosteroid hormones, an approach that we successfully used to identify the brassinosteroid-inactivating enzyme from rice. The identification of such brassinosteroid-inactivating or biosynthesis enzymes from wheat and barley will ultimately lead to targets for breeding approaches to alter stature and yield via the manipulation of the endogenous levels of these growth-promoting hormones.
For example, we may be able to generate plants with elevated levels of brassinosteroids by identifying varieties or mutants that have enhanced activity of key brassinosteroid biosynthesis enzymes and/or reduced activity of enzymes involved in brassinosteroid inactivation. If the plant architectural modifications caused by the elevated levels of brassinosteroids in wheat and barley are similar to those in Arabidopsis, it is anticipated that these wheat varieties would be larger with increased straw yield for cellulosic ethanol.
In contrast, we may be able to generate semi-dwarf plants with reduced levels of brassinosteroids by identifying varieties or mutants that have reduced activity of key brassinosteroid biosynthesis enzymes and/or enhanced activity of enzymes involved in brassinosteroid inactivation. If the plant architectural modifications caused by the reduced levels of brassinosteroids in wheat and barley are similar to those in rice, it is anticipated that these varieties would have increased grain size and yield.
Camelina is a close relative of Arabidopsis and is easily transformed with Arabidopsis DNA. Therefore, we may be able to directly manipulate brassinosteroid levels and stature in Camelina by over-expressing key biosynthesis or inactivating enzymes from Arabidopsis. With increased knowledge of the Camelina genome, we may ultimately be able to identify similar genes in this oil seed crop. Camelina plants with increased seed yield will be the goal of these studies.
Heading using the h3tag
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