The vascular system of plants consists of two conducting tissues, xylem and phloem, which differentiate from procambium cells. Xylem serves as a transporting system for water and signaling molecules and is formed by sequential developmental processes, including cell division/expansion, secondary cell wall deposition, vacuole collapse, and programmed cell death (PCD). PCD during xylem differentiation is accomplished by degradation of cytoplasmic constituents, and it is required for the formation of hollow vessels, known as tracheary elements (TEs). Our recent study revealed that the small GTPase RabG3b acts as a regulator of TE differentiation through its autophagic activation. By using an Arabidopsis in vitro cell culture system, we showed that autophagy is activated during TE differentiation. Overexpression of a constitutively active RabG3b (RabG3bCA) significantly enhances both autophagy and TE differentiation, which are consistently suppressed in transgenic plants overexpressing a dominant negative form (RabG3bDN) or RabG3bRNAi (RabG3bRNAi), a brassinosteroidinsensitive mutant bri1-301, and an autophagy mutant atg5-1. Wood (called secondary xylem) is the most abundant biomass produced by land plants including Populus and Eucalyptus, and therefore is considered to be one of the most cost-effective and renewable bioenergy resources. In an attempt to enhance xylem differentiation and thus to improve biomass traits in poplars, we generated transgenic poplars overexpressing the RabG3bCA form. As notable phenotypes, both stem height and diameter were increased and xylem area in vascular bundles was significantly expanded in RabG3bCA transgenic poplars compared to control plants. Taken together, these results demonstrate that RabG3b regulates xylem differentiation in both Arabidopsis and Populus. This study enhances our understanding of biological mechanisms underlying wood formation and serve as a framework to engineer the quality and quantity of wood as useful biomass.

Slaughter of cattle, pigs, and chickens has increased continuously. In particular, slaughter of chickens has been grown up about 150% in 2010 than that in 2003, that is approximately 120,000 tons. All of them are underwent consigned treatment even though those can be used as a resource and an energy source. With this regards, THR (Thermal Hydrolysis Reaction) leads to reduce water content drastically (<30% in sludge cakes). In addition, Dehydrated solid would be re-used as solid fuels (SRF) as well. In this study, We have applied THR to a plant (10 ton/day) on the basis of our lab and pilot results. Water content of sludge cakes showed with a ranges of 30 to 40% after solid-liquid separation. Dairy SRF produced 1.5 ton/day and its heat capacity for SRF has 6,500 kcal/kg. This gave the steam produced about 12 ton/day throughout the plant operation, suggesting that THR system would expect energy savings.