The Economics of Rapid Multiplication of Hybrid Poplar Biomass Varieties

Background: Poplar (Populus spp.) hybridization is key to advancing biomass yields and conversion efficiency. Once superior varieties are selected, there is a lag in commercial use while they are multiplied to scale. Objective: The purpose of this study was to assess the influence of gains in biomass yield and quality on investment in rapid propagation techniques that speed the time to commercial deployment. Material and Methods: A factorial experiment of propagation method and hybrid variety was conducted to quantify the scale-up rate of in vitro and greenhouse clonal multiplication. These data were used in modeling the internal rate of return (IRR) on investment into rapid propagation as a function of genetic gains in biomass yield and quality and compared to a base case that assumed the standard method of supplying operational varieties in commercial quantities from nurseries as hardwood cuttings, capable of yields of 16.5 Mg ha−1 year−1. Results: Analysis of variance in macro-cutting yield showed that propagation method and varietal effects as well as their interaction were highly significant, with hedge propagation exceeding serial propagation in macro-cutting productivity by a factor of nearly 1.8. The Populus deltoides × P. maximowiczii and the Populus trichocarpa × P. maximowiczii varieties greatly exceeded the multiplication rate of the P. × generosa varieties due to their exceptional response to repeated hedging required to initiate multiple tracks of serial propagation. Analyses of investment into rapid propagation to introduce new material into plantation establishment followed by a 20-year rotation of six coppice harvests showed that gains in biomass yield and quality are warranted for a commitment to rapid propagation systems. The base case analysis was generally favored at yields up to 18 Mg−1 year−1 dependent on pricing. The rapid multiplication analysis proved superior to the base case analysis at the two highest yield levels (27.0 and 31.5 Mg ha−1 year−1,) at all price levels and at yields of 22.5 Mg−1 year−1, dependent on price and farm location. Conclusion: Rapid multiplication is a reliable method to move improved plant material directly into operations when valued appropriately in the marketplace.

Contribution of Matrix, Fusion, Hemagglutinin, and Large Protein Genes of the CAM-70 Measles Virus Vaccine Strain to Efficient Growth in Chicken Embryonic Fibroblasts

ABSTRACT Attenuated live vaccines of measles virus (MV) have been developed from clinical isolates by serial propagation in heterologous cells, mainly chicken embryonic cells. The safety and effectiveness of these vaccines have been well established. However, the molecular mechanism of their attenuation remains a subject of investigation. The CAM-70 MV vaccine strain was developed from the Tanabe strain by serial propagation in chicken embryonic cells. In the present study, we assessed the contribution of each gene in the CAM-70 strain to efficient growth in chicken embryonic fibroblasts (CEF). We used a cloned MV IC323 based on the wild-type IC-B strain and generated a series of IC323s that possess one or more of the CAM-70 genes. Then, we examined the infection of CEF and CEF expressing human signaling lymphocyte activation molecule with the recombinant MVs. Our results demonstrated that MV needs to adapt to CEF at both the entry and postentry steps and that the CAM-70 matrix protein gene plays an important role in adaptation to CEF at the early stage of the virus replication cycle. The CAM-70 large protein gene was responsible for the efficient transcription and replication in CEF, and the CAM-70 hemagglutinin and fusion protein genes were responsible for efficient entry. Investigations focusing on these genes might elucidate unknown molecular mechanisms underlying the attenuation of MV.

Effects of serial propagation, donor age, and genotype on Chamaecyparis nootkatensis physiology and growth traits

Clonal replicates of Chamaecyparis nootkatensis (D. Don) Spach rooted cuttings (ramets) originating from pruned donor hedges (ortets) were grown for 3 years in a completely randomized common garden in southwestern British Columbia. Ramets were cut when ortets were 3, 7, 11, and 15 years old; selected ramets were also serially propagated for one, two, or three cycles, 4 years apart. Serial propagation and physiological and chronological aging effects of ortets on ramets were evaluated for photosynthetic and gas exchange parameters, rooting, height, biomass, and cold hardiness. Genotypic variation typically exceeded treatment differences. Excepting several genotypes, serial propagation had no significant effect on aging for pruned plants. Some genotypes had crooked or plagiotropic growth. These differences strengthened with ortet age, but serial propagation effects varied with genotype. Rooting success was similar across treatments. Detrimental effects of ortet aging were detected only at age 15. Clonal rooting differences were obscured by age 7; 15-year-old material had the lowest rooting success and smallest individuals. Serially propagated ramets from 15-year-old ortets had smaller shoots. No consistent trends were caused by age or serial propagation for other traits. Serial propagation can successfully mass produce tested elite yellow-cedar planting stock up to age 15.

Serial passage of the opportunistic pathogen Aspergillus flavus through an insect host yields decreased saprobic capacity

To study the early stages of the effect of host restriction on pathogen evolution, we subjected the opportunistic fungus Aspergillus flavus to a serial propagation scheme, whereby insect-virulent conidia were selected for repeated passage through an insect host (Galleria mellonella larvae) for 5 generations. Of the 35 lineages promulgated through this scheme, there were no consistent changes in virulence, which was measured by percent mortality of the larvae. There were, however, increases in the number of conidia on the insect cadavers (9 of 35 lineages) and decreases in the number of days between death and the appearance of fungal growth on the cadavers (4 of 35 lineages). Notably, most of the lineages (28 of 35 lineages) demonstrated a statistically significant decrease in the diameter of the colonies subcultured onto artificial media, indicating a decreased ability to grow saprobically. Conversely, most of the A. flavus cultures successively grown on agar media (9 of 10 lineages) exhibited no change in colony diameter after 15 rounds of subculturing. Propagation of the opportunist A. flavus through the insect host G. mellonella resulted in a diminished capacity to grow on an alternate substrate, while maintaining or increasing its ability to use the host as a nutrient supply.Key words: Aspergillus flavus, insect pathogen, Galleria mellonella, serial propagation, emerging diseases.