Figure 2.

Shoot and root growth in CKX2 compared to wild-type (WT) poplar. A and B, No morphological differences were observed between wild-type (A) and transgenic poplar plants (B) upon visual inspection after 3 months of growth in the greenhouse. C–E, In greenhouse, overexpression of the CKX2 gene in roots of poplar gave similar shoot growth (C and D) but significantly enhanced root growth (E) when compared to wild type. Asterisks (*) represent significant differences in dry root biomass between transgenic and wild-type plants in greenhouse according to Student's t test with the pooled variance at P < 0.05. F, No statistically significant differences in stem biomass index (estimated using height × diameter²) were observed between transgenic and wild-type plants after 3 years of growth (2013–2016) in the field according to Student’s t test with the pooled variance at P = 0.05. Bars = ses.