Improved growth in a field trial of transgenic hybrid poplar overexpressing glutamine synthetase

Abstract

Summary• In the present work the performance of transgenic poplars expressing a pine glutamine synthetase (GS) transgene was studied in natural conditions.• A field study of eight independent transgenic lines and control plants was carried out for 3 yr in the province of Granada (Spain).• Transgenic poplars reached average heights that were 21, 36 and 41% greater than control plants after the first, second and third year of growth, respectively. Transgene expression affected plant features with time resulting in increased protein, total GS and ferredoxin-dependent glutamate synthase (Fd-GOGAT) in leaves. However, neither differences in the large subunit of Rubisco (LSU) abundance nor water content were detected between lines. Furthermore, no significant differences were found in total polysaccharide and lignin content in tree trunks.• The analyses of stem diameter, and protein contents in the bark suggest that higher levels of nitrogen reserves accumulated in the stem of transgenics. Our results suggest that modification of GS1 expression may be a useful strategy to complement traditional tree breeding in short rotation plantations.

Somaclonal variations as a mean for obtaining regenerants with different growth rates in poplar (<i>Populus × berolinensis</i> Dipp.)

“…Overexpression of pine glutamine synthetase in transgenic hybrid poplar caused an increase of number of internodes and leaf area [30]. Another example of stem growth regulation by the change of the rate of internodes' production was presented in the work of Tuominen et al [31]: increased IAA content in hybrid aspen due to the inclusion of IAA-synthesizing genes from Agrobacterium tumefaciens led to the slower rate of internodes' production, whereas did not change internode's length.…”

Recombinant DNA modification of gibberellin metabolism alters growth rate and biomass allocation in Populus

“…However, under current stringent laws and regulations pertaining to genetically modified crops, studies are either restricted to greenhouse testing alone (e.g., Eriksson et al 2000;Han et al 2010;Zawaski et al 2012;Jeon et al 2015), or confined to small-scale field trials for a minimum duration of time to minimize or avoid any flowering (e.g., 3 years in Jing et al 2004; only 1 year in Kim et al 2011). Policy changes are likely to be needed to provide a more conducive environment for field trials of transgenic trees if growth rate and plant architecture-modifying transgenes, especially cisgenes and intragenes whose effects are comparable to that from conventional breeding, are to be used in breeding programs (Strauss et al 2015).…”

Improving Nitrogen Use Efficiency in Crops for Sustainable Agriculture

“…By overexpressing a pine GS1 gene in poplar, Jing et al [156] and Man et al [157] observed that the transgenic trees, which were older than five years exhibited a 41%, increase in growth rate, whereas the other phenotypic characteristics of the genetically modified plants remained similar.…”