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Wang L.,Agricultural University of Hebei | Wang L.,Hebei North University | Yang M.,Agricultural University of Hebei | Akinnagbe A.,Agricultural University of Hebei | And 4 more authors.
Plant Biology | Year: 2012

Bacillus thuringiensis (Bt) Cry1Ac protein is a toxin against different leaf-eating lepidopteran insects that attack poplar trees. In the present study, the mode of migration of the Bt-Cry1Ac protein within poplar grafts was investigated. Grafting was done using Pb29 (transgenic poplar 741 with cry1Ac genes), CC71 (transgenic poplar 741 with cry3A genes), non-transgenic poplar 741 and non-transgenic Populus tomentosa, either as scion or as rootstock. In order to detect migration of Bt-Cry1Ac protein from one portion of the graft union to different tissues in the grafted plant, ELISA analysis was employed to assess the content of Bt-Cry1Ac protein in the phloem, xylem, pith and leaves of the grafted poplar. To further verify migration of Bt-Cry1Ac protein, Clostera anachoreta larvae, which are susceptible to Bt-Cry1Ac protein, were fed leaves from the control graft (i.e., graft portion that originally did not contain Bt-Cry1Ac protein). The results showed that Bt-Cry1Ac protein was transported between rootstock and scion mainly through the phloem. Migration of Bt-Cry1Ac protein in the grafted union was also evidenced in that the leaves of the control graft did have a lethal effect on C. anachoreta larvae in laboratory feeding experiments. © 2012 German Botanical Society and The Royal Botanical Society of the Netherlands.

Luttschwager D.,Leibniz Center for Agricultural Landscape Research | Ewald D.,Institute of Forest Genetics | Atanet Alia L.,Leibniz Center for Agricultural Landscape Research
Acta Physiologiae Plantarum | Year: 2016

The breeding of efficient but drought-tolerant poplar clones is very important for short-rotation planting because of frequent periods with low precipitation in Central Europe. Three clones exhibiting very different shoot–root ratios under well-watered conditions were investigated: (1) the aspen clone Großdubrau No. 1 (Populus tremula); (2) the newly bred aspen clone L316 × L9 No. 21 Thermo (P. tremula × P. tremula); (3) and the poplar clone Max2 (P. maximowiczii × P. trichocarpa). All three clones were exposed to moderate drought stress. Photosynthesis and transpiration were measured. The influences of drought on the biometrical parameters of the plants were evaluated. The intrinsic water-use efficiency (WUEintrinsic) was calculated. Height growth was decreased in stressed plants. Photosynthesis and water conductivity were significantly decreased, which is why the WUEintrinsic exhibited a greater increase in Max2 than in the aspen clones. The poplar clone Max2 showed low WUE after sufficient watering, but this parameter exhibited a greater increase under drought stress compared with the aspen clones. Max2 was characterised by intensive root growth that was diminished under stress. In contrast, both aspen clones were less adaptive to moderate drought stress. The capability to change the WUEintrinsic under different water availabilities can be considered a possible selection criterion for breeding. © 2015, Franciszek Górski Institute of Plant Physiology, Polish Academy of Sciences, Kraków.

Robischon M.,Institute of Forest Genetics | Robischon M.,Albert Ludwigs University of Freiburg | Du J.,Institute of Forest Genetics | Du J.,Zhejiang University | And 2 more authors.
Plant Physiology | Year: 2011

The secondary growth of a woody stem requires the formation of a vascular cambium at an appropriate position and proper patterning of the vascular tissues derived from the cambium. Class III homeodomain-leucine zipper (HD ZIP) transcription factors have been implicated in polarity determination and patterning in lateral organs and primary vascular tissues and in the initiation and function of shoot apical meristems. We report here the functional characterization of a Populus class III HD ZIP gene, popREVOLUTA (PRE), that demonstrates another role for class III HD ZIPs in regulating the development of cambia and secondary vascular tissues. PRE is orthologous to Arabidopsis (Arabidopsis thaliana) REVOLUTA and is expressed in both the shoot apical meristem and in the cambial zone and secondary vascular tissues. Transgenic Populus expressing a microRNAresistant form of PRE presents unstable phenotypic abnormalities affecting both primary and secondary growth. Surprisingly, phenotypic changes include abnormal formation of cambia within cortical parenchyma that can produce secondary vascular tissues in reverse polarity. Genes misexpressed in PRE mutants include transcription factors and auxin-related genes previously implicated in class III HD ZIP functions during primary growth. Together, these results suggest that PRE plays a fundamental role in the initiation of the cambium and in regulating the patterning of secondary vascular tissues. © 2010 American Society of Plant Biologists.

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