Growth adaptability analysis of BpCCR1 transgenic Betula platyphylla and selection of elite lines

  Objective  This study aims to conduct a joint analysis of the growth adaptability and stability of the 7-year-old BpCCR1 transgenic birch in 3 test locations, screen high-quality transgenic lines, provide guidance for environmental release and production experiments.

  Method  The tree height, diameter at breast height (DBH) and volume at Maoershan Experimental Forest Farm, Shidaohe Forest Farm and Experimental Forest Farm of northeastern China were measured with 21 BpCCR1 transgenic white birch and 1 wild-type white birch (WT) as the research objects. The AMMI model was used to carry out the interaction effects between the tested lines and the environment, genetic stability and growth adaptability.

  Result  The analysis of variance showed that the differences in height between lines, locations, and interactions between lines and locations were extremely significant (P < 0.01). The best lines for each test location were selected by taking the average volume plus the standard deviation of the tested plants at each test site as the selection criteria for elite transgenic lines. The elite lines selected from the Maoershan Experimental Forest Farm were FC18, FC29, FC40, whose volumes were 72.99%, 51.28%, 64.39% higher than the population average, respectively. The elite lines selected from the Shidaohe Forest Farm were FC7 and FC33, whose volumes were 73.98%, 81.51% higher than the population average, respectively. The elite lines selected from the Ecological Experiment Forest Farm were FC28 and FC29, whose volumes were 69.89% and 73.57% higher than the population average, respectively. The AMMI model was used to evaluate the stability of the height of the tested lines. The lines with better growth stability in the Maoershan Experimental Forest Farm and Ecological Experimental Forest Farm were WT, FC11, FC16, FC19, FC28, FC29 , FC30, FC31, C4. Lines with better growth stability in Shidaohe Forest Farm were FC2, FC7, FC13, FC14, FC18, FC27, FC33, FC40, FC41, C6, C10, C17, C19. 22 test lines were evaluated for stability according to IPC1 and the Dg value. The results showed that FC14, FC29, C19, FC27, FC41, WT, FC13, C4, C10, C6, FC16, FC7, FC28, FC40, C17, FC31, FC18 were high-yielding and stable-yielding lines; FC2, FC11, FC19, and FC33 were high-yielding and unstable-yielding lines; FC30 was a low- yielding and stable-yielding line.

  Conclusion  Both the sense and antisense BpCCR1 transgenes promot tree height of birch. 17 lines were selected based on their growth traits as high-yielding lines with good growth adaptation in the Maoershan Experimental Forest Farm, Shidaohe Forest Farm and Experimental Forest Farm.