Wood is an important raw material and environmentally cost-effective renewable source of energy. However, the molecular biology of wood formation (i.e. secondary growth) is surprisingly understudied. A novel experimental system was employed to study the molecular regulation of secondary xylem formation in Arabidopsis. First, we demonstrate that the weight carried by the stem is a primary signal for the induction of cambium differentiation and the plant hormone, auxin, is a downstream carrier of the signal for this process. We used Arabidopsis whole-transcriptome (23 K) GeneChip analysis to examine gene expression profile changes in the inflorescent stems treated for wood formation by cultural manipulation or artificial weight application. Many of the genes up-regulated in wood-forming stems had auxin responsive cis-acting elements in their promoter region, indicating auxin-mediated regulation of secondary growth. We identified 700 genes that were differentially expressed during the transition from primary growth to secondary growth. More than 40% of the genes that were up-regulated (>5×) were associated with signal transduction and transcriptional regulation. Biological significance of these regulatory genes is discussed in light of the induction and development of secondary xylem.

Biochemical evidence reported so far suggests that rubber synthesis takes place on the surface of rubber particles suspended in the latex of Hevea brasiliensis. We have isolated and characterized a cDNA clone that encodes a protein tightly bound on a small rubber particle. We named this protein small rubber particle protein (SRPP). Prior to this study, this protein was known as a latex allergen, and only its partial amino acid sequence was reported. Sequence analysis revealed that this protein is highly homologous to the rubber elongation factor and the Phaseolus vulgaris stress-related protein. Southern and Northern analyses indicate that the protein is encoded by a single gene and highly expressed in latex. An allergenicity test using the recombinant protein confirmed that the cloned cDNA encodes the known 24-kDa latex allergen. Neither ethylene stimulation nor wounding changed the transcript level of the SRPP gene in H. brasiliensis. An in vitro rubber assay showed that the protein plays a positive role in rubber biosynthesis. Therefore, it is likely that SRPP is a part of the rubber biosynthesis machinery, if not the rubber polymerase, along with the rubber elongation factor.Rubber (cis-1,4-polyisoprene), an isoprenoid polymer with no known physiological function to the plant, is produced in about 2000 plant species with varying degrees of quality and quantity (1). Rubber is the raw material of choice for heavy duty tires and other industrial uses requiring elasticity, flexibility, and resilience. Hevea brasiliensis has been the only commercial source of natural rubber mainly because of its abundance in the tree, its quality, and the ease of harvesting. The diminishing acreage of rubber plantations and life-threatening latex allergy to Hevea rubber, coupled with an increasing demand, have prompted research interests in the study of rubber biosynthesis and the development of alternative rubber sources.In H. brasiliensis, rubber synthesis takes place on the surface of rubber particles suspended in the latex (the cytoplasm of laticifers). The laticifers are specialized vessels that are located adjacent to the phloem of the rubber tree. When severed during tapping, the high turgor pressure inside the laticifers expels latex containing 30 -50% (w/w) cis-1,4-polyisoprene. The latex can be fractionated by centrifugation into three phases: the top fraction containing mostly rubber particles, the metabolically active middle fraction (called C-serum), and the bottom fraction of mainly vacuole-like organelles called lutoids. More than 240 expressed sequence tags (ESTs) 1 have been identified from the latex of H. brasiliensis 2 Kush et al. (2) have shown differential expression of several rubber biosynthesis-related genes in latex. The rubber elongation factor (REF), an enzyme involved in rubber biosynthesis (3), is highly expressed in laticifers (4). Laticiferous cells actively translate the transcribed genes into proteins. About 200 distinct polypeptides are present in the latex of H. brasiliensis (5). Arokiaraj et al...

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Drawing on multiple cases of cross-border merger and acquisitions (CBMAs) by Chinese multinational enterprises (CMNEs), we investigate their search of strategic assets in developed economies (DEs). It is a received view that CMNEs use CBMAs to access strategic assets in DEs so as to address their latecomer disadvantages and competitive weakness. This paper aims to identify the nature of strategic assets that sought after by CMNEs and the post-CBMA integration approach, a partnering approach, adopted in enabling access to these assets. The findings reveal that CMNEs possess firm-specific assets that give them competitive advantages at home and seek for complementary strategic assets in the similar domain, but at a more advanced level. The partnering approach helps securing these strategic assets through no or limited integration, giving autonomy to target firm management team, retaining talents and creating synergy.