EliteTree™: an advanced biomass tree crop technology that features greater wood density and accelerated stem growth

Abstract

Due to wood's potential for large-scale commercial production of biofuels, a rapid increase in the use of wood as a source of energy is expected as policies promoting greater use of renewable energy are adopted globally. However, the economics of purpose-grown tree feedstocks for energy show that these production systems are not fi nancially viable without improvement in the base growth rate. Conventional breeding programs have produced willow and poplar clones that show potential for rapid growth, but current top-performing clones do not grow fast enough for profi table biofuel production. Genetic manipulation of secondary wall biosynthesis is the most direct path to resolving this growth barrier. To that end, we developed an innovative biomass tree crop technology, EliteTree TM , that results in greater wood density and accelerated growth of stems. This technology is built on overexpression of Gibberellin 20-oxidase to increase plant stem growth in both height and diameter and increase lignocellulosic biomass accumulation through overexpression of the transcription factor MYB46, which is a master regulator for secondary wall biosynthesis. EliteTree TM technology uses 2A-mediated bicistronic gene expression, with our proprietary utility promoter DX15, such that the genetic manipulation is limited to wood tissue, yielding transgenic poplars with xylem-specifi c coexpression of MYB46 and PdGA20ox1. The development of faster growing elite tree genotypes with increased wood density and growth rates will pave the way for truly sustainable and economically 522

Fire alters the availability of soil nutrients and accelerates growth of Eucalyptus grandis in Zambia

“…In softwoods, increased growth rate produces wider growth rings, and narrower latewood than early wood, resulting in relatively low wood density (Saranpää 2003;Sopushynskyy et al 2017). However, in hardwood plantations, including Eucalyptus spp., the effect of increased growth rate is still unclear (Saranpää 2003;Carrillo et al 2015;Ko et al 2017). In this study, slow growing trees on unburned sites had higher density than faster growing trees on burned sites, consistent with reports by King et al (2006), Sotelo Montes et al (2017, and Pretzsch et al (2018).…”

Growth of Paulownia ssp. Interspecific Hybrid ‘Oxytree’ Micropropagated Nursery Plants under the Influence of Plant-Growth Regulators

“…All those chemicals stimulated the elongation of paulownia stems in comparison with the control (Table 2). Such an effect, as well as strengthening apical dominance, is a clearly visible symptom of gibberellin application in many woody plants [17,23,37,40,41]. Gibberellins (GAs) are especially involved in heterosis for shoot growth [42,43].…”

Wood forming tissue‐specific bicistronic expression of PdGA20ox1 and PtrMYB221 improves both the quality and quantity of woody biomass production in a hybrid poplar

“…The resulting transgenic poplars showed a superior woody biomass without growth penalties. Thus, by substituting suitable transcriptional regulators as demonstrated (Ko et al ., ), our strategy can be utilized as an efficient biotechnological tool for producing the desired woody biomass and expanded to various bioenergy crops.…”

“…While most alternate energy sources produce electric energy, biomass can be converted into various forms of energy including not only electricity, but also gas and liquid energy, which can be used directly in current internal combustion engines (Albers et al, 2016;Chundawat et al, 2011;L opez-Hidalgo et al, 2017;Vanholme et al, 2013). Recently, many studies have been conducted to produce biofuels from woody biomass, which account for more than 90% of the total biomass produced on Earth (Castro et al, 2014;Crawford et al, 2016;Ko et al, 2017;Serapiglia et al, 2013;Vo et al, 2017;Zhu et al, 2010). Populus species can serve as an ideal woody biomass because of their fast growth characteristics for feedstock supply and inherent secondary cell wall characteristics with suitable cellulose to lignin ratios for utilization as a bioethanol crop (Porth and El-Kassaby, 2015).…”