The role of leaf chemistry in Melampsora medusae infection of hybrid poplar: effects of leaf development and fungicide treatment

2005 ◽  
Vol 35 (4) ◽  
pp. 763-771 ◽  
Author(s):  
Jon D Johnson ◽  
Yong Kim
Keyword(s):  
Populus Deltoides ◽  
Populus Trichocarpa ◽  
Hybrid Poplar ◽  
Gene Modification ◽  
Defense Compounds ◽  
Melampsora Medusae ◽  
Or Gene ◽  
Plastochron Index

Immature leaves of poplars are immune to Melampsora leaf rust infection, regardless of the level of resistance or susceptibility of older leaves. Leaf phenolic and protein concentrations were quantified in leaves of varying maturity (measured by leaf plastochron index, LPI) from a rust-susceptible, interspecific hybrid poplar clone, 47-174 (Populus trichocarpa Torr. & Gray × Populus deltoides Bartr. ex Marsh.). Using leaf water extracts and apoplastic solutions, concentrations of phenolics and proteins decreased as LPI increased. Urediniospore germination increased 3-fold, and hyphae elongation increased 3.5-fold as LPI increased from 1 to 11. Inoculation significantly increased concentrations from 9% (LPI 5) to over 120% (LPI 11). Application of triadimefon (Bayleton®) significantly increased the apoplastic concentrations of phenolics and proteins by 43% and 25%, respectively. In vitro urediniospore germination and hyphae elongation decreased over 7-fold and 3-fold, respectively, in these leaves, to levels comparable to immature leaves. This study has shown that defense compounds are present in immature poplar leaves that likely contribute to Melampsora medusae rust immunity, and that triadimefon application created a similar immunity in susceptible leaves. Identification of specific compounds associated with this immunity could assist in the development of resistant poplar clones through traditional breeding or gene modification.

Bt-Cry3Aa transgene expression reduces insect damage and improves growth in field-grown hybrid poplar

2014 ◽  
Vol 44 (1) ◽  
pp. 28-35 ◽  
Author(s):  
Amy L. Klocko ◽  
Richard Meilan ◽  
Rosalind R. James ◽  
Venkatesh Viswanath ◽  
Cathleen Ma ◽  
...  
Keyword(s):  
Large Scale ◽  
Populus Deltoides ◽  
Integrated Management ◽  
Populus Trichocarpa ◽  
Hybrid Poplar ◽  
Volume Growth ◽  
Field Trials ◽  
Leaf Beetle ◽  
Insect Damage ◽  
Beetle Damage

The stability and value of transgenic pest resistance for promoting tree growth are poorly understood. These data are essential for determining if such trees could be beneficial to commercial growers in the face of substantial regulatory and marketing costs. We investigated growth and insect resistance in hybrid poplar expressing the cry3Aa transgene in two field trials. An initial screening of 502 trees comprising 51 transgenic gene insertion events in four clonal backgrounds (Populus trichocarpa × Populus deltoides, clones 24-305, 50-197, and 198-434; and P. deltoides × Populus nigra, clone OP-367) resulted in transgenic trees with greatly reduced insect damage. A large-scale study of 402 trees from nine insertion events in clone OP-367, conducted over two growing seasons, demonstrated reduced tree damage and significantly increased volume growth (mean 14%). Quantification of Cry3Aa protein indicated high levels of expression, which continued after 14 years of annual or biannual coppice in a clone bank. With integrated management, the cry3Aa gene appears to be a highly effective tool for protecting against leaf beetle damage and improving yields from poplar plantations.

scholarly journals Defining hybrid poplar (Populus deltoides × Populus trichocarpa) tolerance to ozone: identifying key parameters

2009 ◽  
Vol 32 (1) ◽  
pp. 31-45 ◽  
Author(s):  
A. RYAN ◽  
C. COJOCARIU ◽  
M. POSSELL ◽  
W. J. DAVIES ◽  
C. N. HEWITT
Keyword(s):  
Populus Deltoides ◽  
Populus Trichocarpa ◽  
Hybrid Poplar

scholarly journals The Transcriptional Response of Hybrid Poplar (Populus trichocarpa x P. deltoids) to Infection by Melampsora medusae Leaf Rust Involves Induction of Flavonoid Pathway Genes Leading to the Accumulation of Proanthocyanidins

2007 ◽  
Vol 20 (7) ◽  
pp. 816-831 ◽  
Author(s):  
Manoela Miranda ◽  
Steven G. Ralph ◽  
Robin Mellway ◽  
Rick White ◽  
Michele C. Heath ◽  
...  
Keyword(s):  
Leaf Rust ◽  
Induced Defense ◽  
Populus Trichocarpa ◽  
Condensed Tannin ◽  
Hybrid Poplar ◽  
Transcriptional Response ◽  
Phytochemical Analysis ◽  
Defense Genes ◽  
Melampsora Medusae ◽  
Genes Encoding

The transcriptional response of hybrid poplar (Populus trichocarpa × P. deltoids) to poplar leaf rust (Melampsora medusae) infection was studied using the Populus 15.5K cDNA microarray. Pronounced changes in the transcriptome were observed, with approximately 20% of genes on the array showing either induction or repression of transcription within the 9-day infection timecourse. A small number of pathogen-defense genes encoding PR-1, chitinases, and other pathogenesis-related proteins were consistently upregulated throughout the experimental period, but most genes were affected only at individual timepoints. The largest number of changes in gene expression was observed late in the infection at 6 to 9 days postinoculation (dpi). At these timepoints, genes encoding enzymes required for proanthocyanidin (condensed tannin) synthesis were upregulated dramatically. Phytochemical analysis confirmed that, late in the infection, proanthocyanidin levels increased in infected leaves. Strongly M. medusae-repressed genes at 9 dpi included previously characterized wound- and herbivore-induced defense genes, which suggests antagonism between the tree responses to insect feeding and M. medusae infection. In this highly compatible plant-pathogen interaction, we postulate that the biotrophic pathogen evades detection and suppresses early host responses.

scholarly journals A sex-specific role for androgens in angiogenesis

2010 ◽  
Vol 207 (2) ◽  
pp. 345-352 ◽  
Author(s):  
Daniel P. Sieveking ◽  
Patrick Lim ◽  
Renée W.Y. Chow ◽  
Louise L. Dunn ◽  
Shisan Bao ◽  
...  
Keyword(s):  
Serum Levels ◽  
Dependent Manner ◽  
Androgen Treatment ◽  
Androgen Exposure ◽  
Androgen Sensitivity ◽  
Males And Females ◽  
Or Gene

Mounting evidence suggests that in men, serum levels of testosterone are negatively correlated to cardiovascular and all-cause mortality. We studied the role of androgens in angiogenesis, a process critical in cardiovascular repair/regeneration, in males and females. Androgen exposure augmented key angiogenic events in vitro. Strikingly, this occurred in male but not female endothelial cells (ECs). Androgen receptor (AR) antagonism or gene knockdown abrogated these effects in male ECs. Overexpression of AR in female ECs conferred androgen sensitivity with respect to angiogenesis. In vivo, castration dramatically reduced neovascularization of Matrigel plugs. Androgen treatment fully reversed this effect in male mice but had no effect in female mice. Furthermore, orchidectomy impaired blood-flow recovery from hindlimb ischemia, a finding rescued by androgen treatment. Our findings suggest that endogenous androgens modulate angiogenesis in a sex-dependent manner, with implications for the role of androgen replacement in men.

scholarly journals ERα-Targeting PROTAC as a Chemical Knockdown Tool to Investigate the Estrogen Receptor Function in Rat Menopausal Arthritis

2021 ◽  
Vol 12 ◽  
Author(s):  
Li Duan ◽  
Xiao Xu ◽  
Limei Xu ◽  
Caining Wen ◽  
Kan Ouyang ◽  
...  
Keyword(s):  
Estrogen Receptor ◽  
Estrogen Receptor Alpha ◽  
Gene Knockouts ◽  
Matrix Metabolism ◽  
Or Gene ◽  
Genetic Compensation ◽  
Embryonic Death

Proteolytic targeting chimeras (PROTACs) is a rapid and reversible chemical knockout method. Compared with traditional gene-editing tools, it can avoid potential genetic compensation, misunderstandings caused by spontaneous mutations, or gene knockouts that lead to embryonic death. To study the role of estrogen receptor alpha (ERα) in the occurrence and progression of menopausal arthritis, we report a chemical knockout strategy in which stable peptide-based (PROTACs) against ERα to inhibit their function. This chemical knockdown strategy can effectively and quickly inhibit ERα protein in vivo and in vitro. In the rat menopausal arthritis model, this study showed that inhibiting estrogen function by degrading ERα can significantly interfere with cartilage matrix metabolism and cause menopausal arthritis by up-regulating matrix metalloproteinase (MMP-13). The results of this study indicate that ERα is a crucial estrogen receptor for maintaining cartilage metabolism. Inhibition of ERα function by PROTACs can promote the progression of osteoarthritis.

scholarly journals The Effects of Initial Spacing and Rectangularity on the Early Growth of Hybrid Poplar

2008 ◽  
Vol 23 (4) ◽  
pp. 189-196 ◽  
Author(s):  
Wayne D. Johnstone
Keyword(s):  
Populus Deltoides ◽  
Populus Trichocarpa ◽  
Hybrid Poplar ◽  
Early Growth ◽  
Row Spacing ◽  
Individual Tree ◽  
Tree Diameter ◽  
Initial Spacing ◽  
The Individual ◽  
Plantation Spacing

Abstract Hybrid poplar (Populus trichocarpa Torr. and Gray × Populus deltoides Marsh.) plantations, at two locations in southern British Columbia, were examined 9 years after planting, to determine the effects of plantation spacing on individual-tree and per-hectare growth and development. At both locations, spacing had a direct, significant effect on virtually all of the individual-tree characteristics examined. For a given amount of growing space per tree, rectangularity (within-row/between-row spacing ratios) had no significant effect on individual-tree diameter, height, or total bole volume. Virtually all of the per-hectare characteristics examined were not significantly affected by spacing at either location.

Phenotypic variation in growth and biomass distribution for two advanced-generation pedigrees of hybrid poplar

2005 ◽  
Vol 35 (8) ◽  
pp. 1779-1789 ◽  
Author(s):  
Stan D Wullschleger ◽  
T M Yin ◽  
S P DiFazio ◽  
T J Tschaplinski ◽  
L E Gunter ◽  
...  
Keyword(s):  
Genetic Control ◽  
Phenotypic Variation ◽  
Populus Deltoides ◽  
Populus Trichocarpa ◽  
Hybrid Poplar ◽  
Biological Research ◽  
Total Biomass ◽  
Biomass Distribution ◽  
Coarse Roots ◽  
Fractional Distribution

To assess the genetic control of biomass distribution in trees, phenotypic variation in the distribution of dry mass to stems, branches, leaves, coarse roots, and fine roots was examined in two hybrid poplar (Populus trichocarpa Torr. & A. Gray (T) × Populus deltoides Bartr. ex Marsh. (D)) families grown under field conditions. Family 331 was an inbred F2 (TD × TD) pedigree, whereas family 13 was an outbred backcross BC1 (TD × D) pedigree. Fractional distribution of total whole-tree biomass to shoots and roots during their establishment year averaged (±SD) 0.62 ± 0.09 and 0.38 ± 0.09, respectively, across 247 genotypes in family 331, and 0.57 ± 0.06 and 0.43 ± 0.06, respectively, across 160 genotypes in family 13. In contrast, fractional distribution of total biomass in 2-year-old trees was 0.79 ± 0.04 to shoots and 0.21 ± 0.04 to roots. Allometric analysis indicated that as trees increased in age, biomass was preferentially distributed to stems and branches, whereas distribution to roots declined. Quantitative trait loci (QTL) analysis for family 13 indicated 31 QTL (likelihood of odds >2.5) for traits measured. The percent phenotypic variation explained by any single QTL ranged from 7.5% to 18.3% and averaged 11.2% across all QTL. These results show that aboveground and belowground patterns of biomass distribution are under genetic control. This finding has wide-ranging implications for carbon sequestration, phytoremediation, and basic biological research in trees.

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