(491b) Progress In Biomass Trait Screening Using a High Throughput Digestibility Platform

A key step in the development of a viable lignocellulosic ethanol industry is the improvement of the plants that are to be used as biomass feedstocks.  We have previously described a high throughput cell wall digestibility platform (HTDP) to facilitate the identification and evaluation of feedstock plants.  Cell wall digestibility is assayed by the amount of free Glc and Xyl released after chemical pretreatment and incubation with a commercial cellulase mixture (Accellerase).  One key component of the HTDP is a custom-designed workstation that grinds and dispenses individual plant biomass to within 0.1 mg accuracy.  Combining this workstation with a second key component, a laboratory information management system (LIMS), provides the basis for generating a quantitative measure of cell wall digestibility on a vast number of samples. 

The results presented in this talk summarize cell wall digestibility screening projects carried out in the two years since the HTDP opened.  A collection of approximately 7,000 Brachypodium EMS mutant M2 lines have been screened.  Classes of outliers are identified and studies are underway to further characterize the mutant lines.  A collection of approximately 1,200 Arabidopsis T-DNA lines with insertions in cell wall biosynthesis-related genes have been screened for differences in cell wall digestibility.  The chemical and genetic characterization of these lines is presented.  Corn lines comprising a University of Wisconsin Diversity Set have been screened recently using corn stalk core samples.  An initial survey of outliers is presented.  Results for transgenic poplars containing knock-down insertions for decreasing the expression of the CCR gene are also presented.  The poplar screening studies compare the cell wall digestibility of the transgenic and wild type poplar in response to a variety of pretreatment conditions as well as to geographical field location.  Substantial differences in cell wall digestibility of the transgenic and wild type poplar are shown as the above parameters are varied.

In Summary, the HTDP is an extremely useful tool, demonstrating utility as a screening tool to identify improved plants from large sample populations (Brachypodium).  In addition, the HTDP is flexible to accommodate novel sampling methods (corn stalk cores).  Furthermore, once interesting plants are identified, they can be further tested in the HTDP using a number of varied pretreatment conditions (poplar).