Waterlogging tolerance and wood properties of transgenic Populus alba × glandulosa expressing Vitreoscilla hemoglobin gene (Vgb)

Because overexpression of Vitreoscilla hemoglobin gene (Vgb) gene in plants can enhance tolerance to waterlogging, here Vgb was inserted into Populus alba × glandulosa to investigate its expression and effects on growth and physiological responses to waterlogging stress in the transgenic poplars. Southern blotting and RT-PCR analysis of Vgb-transgenic P. alba × glandulosa showed that the Vgb gene was integrated into the genome of the V13-81 and V13-85 transgenic lines and expressed. In greenhouse waterlogging stress tests, mortality of the transgenic poplar was significant lower than that of nontransgenic plants with increasing treatment time from 2 to 22 days. The transgenic plants had higher chlorophyll content and less chloroplast damage than in the control plants. Additionally, starch accumulation increased, and growth was enhanced in the transgenic plants, suggesting that the Vgb-expressing lines had improved energy reserves. Field trials of the transgenic poplar suggested that Vgb expression promotes growth and influences wood quality. Taken together, our results suggest that the expression of Vgb can increase the accumulation of chlorophyll and starch in the transgenic poplar, improve its ability to endure flooding, and improve growth and wood quality of the transgenic plants.