Analysis of the Genotype Interaction of Four-Year-Old Populus euramericana Using the BLUP-GGE Technique

Poplar is a commercially globalized tree species that provides energy and economic and ecological support. To evaluate the twelve hybrid Populus euramericana genotypes developed in China, a total of six locations were selected for the current study, comprising four climatic types and three kinds of soil. The objective of this study was to characterize the early stages of Populus euramericana growth and to test the locations; to identify good genotypes for stable and high yield; and to offer practical experience and technical assistance for further breeding of Populus euramericana. The main research methods included the statistical description of tree heights and diameter at breast height (DBH), the establishment of a mixed effect model to analyze the genotype and environmental interaction effect (G × E), the use of best linear unbiased prediction (BLUP) values as GGE biplots to achieve visual screening, and the calculation of genetic parameters. Results show that the genotype effect (G), the environmental effect (E), and the G × E interaction is significant; the BLUP value has a strong correspondence with the observed value; the goodness of fit of all biplots can explain more than 85% of the variation; the broad-sense heritability of tree height and DBH is 0.13 and 0.3, respectively; and the type-B correlation is 0.36 and 0.65. In addition, G5, G7, G4, and G9 are excellent genotypes with high yield and stability; using the tree height and DBH of these four genotypes can achieve genetic gains of 3.35% and 0.81%. The conclusions of this study are as follows: the rank-change and scale-effect interactions were distinct; G, E, and G × E all had a significant effect on the growth of poplar trees during their early stage; G4, G5, G7, and G9 genotypes have favorable development characteristics; and N146 is an excellent source of paternal genetics.

Analysis of Genotype-Interaction of a 4-Year-Old Populus euramericana Using BLUP-GGE Technique

Poplar is a globalized commercial tree species that supports humanity's economy, energy, and ecology. To evaluate the twelve hybrid Populus euramericana genotypes developed in China, a total of six locations were selected for the test, comprising four climatic types and three soil kinds. The objective of this study is to characterize the early stages of Populus euramericana growth and test locations; to identify good genotypes for stable and high yield that may be encouraged; and to offer practical experience and technical assistance for further breeding of Populus euramericana. Main research methods include the statistical description of tree heights and diameter at breast heights[DBH], the establishment of a mixed effect model to analyze the genotype and environmental interaction effect [G×E], the use of best linear unbiased prediction[BLUP] values as GGE biplots to achieve visual screening, and the calculation of genetic parameters. Results show that the genotype effect [G], the environmental effect [E], and the G×E is significant; the BLUP value has a strong correspondence with the observed value; the goodness of fit of all biplots can explain more than 85% of the variation; broad-sense heritability of tree height and DBH is 0.13 and 0.3, type-B correlation is 0.36 and 0.65; G5, G7, G4 and G9 are excellent genotypes with high yield and stability; using these four genotypes tree height and DBH can get 3.35% and 0.81% genetic gains.The study concludes as follows: Rank-change interaction and scale-effect interaction were distinctly occurred. The G, E, and G×E all had a significant effect on the growth of poplar trees during their early stage. G4, G5, G7, and G9 genotypes have favorable development characteristics. N146 is a great source of paternal genetics.

The Effects of Magnetic Treatment On Seedling Growth, Nitrogen Metabolism, And Mineral Nutrient Contents In Populus×Euramericana 'Neva' Under Cadmium Stress

Background: The potted experiment was carried out to investigate the mechanism of nutrient metabolism and seedling growth caused by magnetic treatment (MT) following exposure to cadmium (Cd) stress. One-year-old seedlings of Populus×euramericana 'Neva' were treated with different Cd(NO3)2 solutions for 30 days. Properties of seedling growth and root morphology were promoted by MT under Cd exposure.Results: Contents of ammonium (NH4+-N), nitrate (NO3--N), and total nitrogen (TN) in leaves, also NH4+-N and TN in roots, were increased by MT combined with Cd-stress, although NO3--N content was decreased. Activities of nitrate reductase (NR), nitrite reductase (NiR), glutathione reductase (GR), and glutamate synthase (GOGAT) in leaves and activities of NR, GS and GOGAT in roots were stimulated by MT; conversely, NiR activity in roots was inhibited. MT improved the synthesis of cysteine (Cys) and glutamine (Gln) in leaves and reduced the contents of glutamic acid (Glu) and glycine (Gly), while contents of Cys, Glu, Gln, and Gly were increased in roots. (4) The contents of Ca, Mg, Fe, Mn, Zn and Cu were increased by MT under Cd stress in leaves, whereas content of K was reduced. In roots, contents of K, Ca, and Fe were increased by MT under Cd-stress, but the contents of Na, Mg, Mn, Zn, and Cu were decreased.Conclusions: Magnetization could regulate the uptake of mineral nutrients by roots and translocation from the roots to aboveground parts by affecting the root morphology. MT could also improve nitrogen assimilation and the synthesis of free amino acids by stimulating the activities of key enzymes.

Analyses of Microstructure and Dynamic Deposition of Cell Wall Components in Xylem Provide Insights into Differences between Two Black Poplar Cultivars

The chemical composition of the cell wall varies between species and even within the same species, and impacts the properties of the cell wall. In this study, the dynamic chemical compositions of the xylem cell walls of two black poplar cultivars, Populus × euramericana ‘Zhonglin46’ and Populus × euramericana ‘Neva,’ were investigated in situ using stimulated Raman scattering microscopy (SRS). Meanwhile, the pectin structural features were examined using immunofluorescence methods. The results showed that Neva displayed faster thickening of the fiber cell walls than Zhonglin46 did, and it had a greater cell wall thickness in mature xylem. A faster deposition speed of lignin and cellulose during xylem maturation was revealed in Neva. Significantly higher lignin contents were found in the mature xylem of Neva compared with those of Zhonglin46, while no obvious differences in cellulose deposition in mature xylem were observed between the two cultivars. The patterns of pectin deposition during xylem maturation were similar in the two cultivars, but more pectin was found in the mature xylem of Neva than in that of Zhonglin46. The chemical deposition patterns account for the anatomical feature differences between the cultivars. These results provide valuable insights into the chemical deposition and anatomical differences between cultivars, and they might be helpful in understanding the wood growth processes and facilitating the utilization of different poplar cultivars.

Cloning and overexpression of PeWRKY31 from Populus × euramericana enhances salt and biological tolerance in transgenic Nicotiana

Background As important forest tree species, biological stress and soil salinization are important factors that restrict the growth of Populus × euramericana. WRKYs are important transcription factors in plants that can regulate plant responses to biotic and abiotic stresses. In this study, PeWRKY31 was isolated from Populus × euramericana, and its bioinformation, salt resistance and insect resistance were analyzed. This study aims to provide guidance for producing salt-resistant and insect-resistant poplars. Results PeWRKY31 has a predicted open reading frame (ORF) of 1842 bp that encodes 613 amino acids. The predicted protein is the unstable, acidic, and hydrophilic protein with a molecular weight of 66.34 kDa, and it has numerous potential phosphorylation sites, chiefly on serines and threonines. PeWRKY31 is a zinc-finger C2H2 type-II WRKY TF that is closely related to WRKY TFs of Populus tomentosa, and localizes to the nucleus. A PeWRKY31 overexpression vector was constructed and transformed into Nicotiana tabacum L. Overexpression of PeWRKY31 improved the salt tolerance and insect resistance of the transgenic tobacco. Transcriptome sequencing and KEGG enrichment analysis showed the elevated expression of genes related to glutathione metabolism, plant hormone signal transduction, and MAPK signaling pathways, the functions of which were important in plant salt tolerance and insect resistance in the overexpressing tobacco line. Conclusions PeWRKY31 was isolated from Populus × euramericana. Overexpression of PeWRKY31 improved the resistance of transgenic plant to salt stress and pest stress. The study provides references for the generation of stress-resistant lines with potentially great economic benefit.

Bacterial Canker Disease on Populus × euramericana Caused by Lonsdalea populi in Serbia

Populus × euramericana (Dode) Guinier clone (cl.) “I-214” is a fast-growing interspecific hybrid between Eastern cottonwood (P. deltoides Bartr. ex Marsh) and European black poplar (Populus nigra L.). Populus × euramericana was introduced into Serbia in the 1950s and has become one of the most widely grown poplar species. In September 2019, cankers were observed on stems and branches of P. × euramericana cl. “I-214” trees in a two-year-old poplar plantation in the province of Vojvodina, Serbia. The canker tissue was soft and watery, and a colorless fluid that smelled rotten flowed from the cracks in the bark, suggesting possible bacterial disease. After two weeks, diseased trees experienced crown die-back and oozing of foamy, odorous exudates and this study aimed to identify the causal agent of the disease. Canker margins and exudates were collected from 20 symptomatic trees. The associated bacterium was isolated and identified using biochemical characteristics, phylogenetic analyses based on 16S rRNA gene sequences, and multilocus sequence analyses (MLSA) based on partial sequencing of three housekeeping genes (gyrB, infB, and atpD). The pathogen was identified as Lonsdalea populi. Pathogenicity tests were conducted on rooted cuttings of P. × euramericana cl. “I-214” in an environmental test chamber and demonstrated that the isolated bacterial strain was able to reproduce symptoms of softened, water-soaked cankers and exudation. To the best of our knowledge, this is the first report of L. populi causing bacterial canker disease on P. × euramericana cl. “I-214” in Serbia and in southeastern Europe (SEE). It is also the first report of a bacterial disease on hybrid poplars, including P. × euramericana in this country and in SEE. If the disease spreads into new areas, selection for L. populi resistance may need to be integrated into future poplar breeding programs.