591 SummarySolanum tuberosum is a frost-sensitive species incapable of cold acclimation. A brief exposure to frost can significantly reduce its yields, while hard frosts can completely destroy entire crops. Thus, gains in freezing tolerance of even a few degrees would be of considerable benefit relative to frost damage. The S . tuberosum cv. Umatilla was transformed with three Arabidopsis CBF genes ( AtCBF1-3 ) driven by either a constitutive CaMV35S or a stress-inducible Arabidopsis rd29A promoter. AtCBF1 and AtCBF3 overexpression via the 35S promoter increased freezing tolerance about 2 ° C, whereas AtCBF2 over-expression failed to increase freezing tolerance. Transgenic plants of AtCBF1 and AtCBF3 driven by the rd29A promoter reached the same level of freezing tolerance as the 35S versions within a few hours of exposure to low but non-freezing temperatures.Constitutive expression of AtCBF genes was associated with negative phenotypes, including smaller leaves, stunted plants, delayed flowering, and reduction or lack of tuber production.While imparting the same degree of freezing tolerance, control of AtCBF expression via the stress-inducible promoter ameliorated these negative phenotypic effects and restored tuber production to levels similar to wild-type plants. These results suggest that use of a stressinducible promoter to direct CBF transgene expression can yield significant gains in freezing tolerance without negatively impacting agronomically important traits in potato.

These authors contributed equally and are considered co-first authors.

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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

Heracleum moellendorffii Hance is a non-woody forest plant widely used in China, Korea, and Japan because of its various therapeutic properties. However, the genetic details of the carotenoid pathway (CP), xanthophyll pathway (XP), and apocarotenoid pathway (AP) genes have not been studied. Thus, the CP, XP, and AP genes of H. moellendorffii were detected and analyzed. A total of fifteen genes were identified, of which eight, four, and three belonged to CP, XP, and AP, respectively. All identified genes possessed full open reading frames. Phylogenetic characterization of the identified gene sequences showed the highest similarity with other higher plants. Multiple alignments and 3D dimensional structures showed several diverse conserved motifs, such as the carotene-binding motif, dinucleotide-binding motif, and aspartate or glutamate residues. The results of real-time PCR showed that the CP, XP, and AP genes were highly expressed in leaves, followed by the stems and roots. In total, eight different individual carotenoids were identified using HPLC analysis. The highest individual and total carotenoid content were achieved in the leaves, followed by the stems and roots. This study will provide more information on the gene structure of the CP, XP, and AP genes, which may help to increase the accumulation of carotenoids in H. moellendorffii through genetic engineering. These results could be helpful for further molecular and functional studies of CP, XP, and AP genes.