Researchers Evaluate the Agronomic Performance of Transgenic Populus deltoides Trees for Biofuel Production

Recalcitrance, one of the major barriers to the development of lignocellulosic feedstock, can be reduced by targeting genes involved in cell wall biosynthesis. However, this can have unintended consequences that compromise the agronomic performance under field conditions. West Virginia University now reports the results of a field trial of transgenic Populus deltoides lines that had previously demonstrated reduced recalcitrance without yield penalties under greenhouse conditions.

Survival and productivity of the trial were excellent in the first year, and there were no evidence of any reduced performance of the transgenic lines. Traits related to yield, crown architecture, herbivory, pathogen response, and frost damage showed few significant differences between target gene transgenics and wild types.

However, lines overexpressing the DUF231 gene, a putative O-acetyltransferase, showed early bud flush and marginally increased height growth. Meanwhile, lines overexpressing the DUF266 gene, a putative glycosyltransferase, had significantly decreased stem internode length and slightly higher volume index. Finally, lines overexpressing the PFD2 gene, a putative member of the prefoldin complex, had a slightly reduced volume index.

This field trial demonstrates that these cell wall modifications, which decreased cell wall recalcitrance under laboratory conditions, did not seriously compromise first-year performance in the field. This bodes well for the potential utility of these lines as advanced biofuels feedstock.