UDP-glucose 4-epimerase (UGE; EC 5.1.3.2) is an enzyme that plays an essential role in the interconverts UDP-D-glucose (UDP-Glc) and UDP-Dgalactose (UDP-Gal). Five members of the Chinese cabbage (Brassica rapa) UDP-glucose 4-epimerase gene family, designated BrUGE1 to BrUGE5, have been cloned and characterized. Quantitative PCR shows that the BrUGE1and BrUGE4 mRNA are most abundant among other BrUGE genes, accounting for more than 55% of total BrUGE transcripts in most of the tissues examined. All genes showed organ specific expression pattern, two of which (BrUGE1 and 4) actively responded after Pectobacterium carotovorum subsp. carotovorum infection, while four genes (BrUGE-1, -3, -4 and -5)were shown to respond considerably against salt, drought and abscisic acid (ABA) treatments. To better understand the function of the UGE gene, we constructed a recombinant pART vector carrying the BrUGE1 gene under the control of the CaMV 35S promoter and nos terminator and transformed using Agrobacterium tumefaciens. We then investigated BrUGE1 overexpressing rice lines at the physiological and molecular levels under biotic and abiotic stress conditions. Bioassay of T3 progeny lines of the transgenic plants in Yoshida solution containing 120 mM Nacl for 2 weeks, confirmed that the BrUGE1 enhances salt tolerance to transgenic rice plants. Also T3 progeny lines of the transgenic plants, when exposed to infection caused by Xanthomonas oryzae pv oryzae, showed tolerance to bacterial blight. These results showed that BrUGE1 can be used as potential genetic resource for engineering Brassica with multiple stress resistance.

Comparative time-course expression analyses were carried out to analyze the expression levels of 60 soybean WRKY genes during abiotic stress in order to search for the stress-inducible WRKY genes. Five GmWRKY(Glycine max WKRY) genes having the significant differential expression in response to the drought stress and abscisic acid(ABA) hormone application were further investigated for their expression profiles with various stresses such as drought, high salinity, cold and with ABA treatments by the quantitative real-time PCR analyses. In this research, the full-length cDNAs of five GmWRKY were isolated for the further studies. Five GmWRKY proteins were tested for their transcription activation in the yeast assay system. GmWRKY3 proteins showed the very high transcriptional activities and the other two GmWRKY proteins displayed moderate levels of transactivation while the remaining two GmWRKY proteins lacked transactivation in yeast. Subcellular localization of five GmWRKY proteins was analyzed via the green fluorescent protein-GmWRKY fusion protein in tobacco plant cell and all of GmWRKY proteins were targeted to the nucleus. In order to analyze the function of GmWRKY genes in plant, 35S:GmWRKY overexpression(OE) transgenic Arabidopsis were generated. Root growth and germination rates in transgenic OE plants were investigated in the media supplemented with mannitol, NaCl or ABA compared with that of wild-type(WT) plants. The 35S:GmWRKY42 transgenic Arabidopsis displayed reduced tolerance to drought stress compared to the WT. The results of this systematic analysis of the GmWRKY family responsive to abiotic stress will provide novel tools and resources for the development of improved drought tolerant transgenic soybean cultivars

The plant cell wall is an extracellular matrix, which can be viewed as a multifunctional subcellular compartment involving many fields of research: growth and development, plant-pathogen interactions, stress, cell-to-cell signaling, metabolic processes, biomaterials and biofuels, and many others. Given its importance, much of the research effort has been directed toward investigating the plant cell walls containing plant cell wall proteins, which are essential constituents of plant cell walls and play essential roles in many biological processes, and yet there is still not a distinct repertoire of the plant cell wall proteins. Several functional screen procedures including a yeast secretion trap, an Agrobacterium-mediated transient expression assay and a subcellular localization study, have been recently optimised to confirm secretion and localization of an ever-growing list of plant cell wall proteins. These functional screen approaches collectively provide a powerful suite of means to identify and characterize a dynamic and complex plant cell wall proteome. Thus, the potential outcomes of plant cell wall functional genomics will enable plant breeding programs to develop new strategies for improvement of crop quality.

Dehydrins (LEA Dll proteins) are one of the typical families of plant proteins that accumulate in response to dehydration, cold stress, abscisic acid, or during seed maturation. A 1.3-kb cDNA was cloned from a cDNA expression library of 5-day-old germinating maize scutellums under drought stress. The deduced protein sequence indicated a dehydrin gene encoding SK3 LEA protein typically expressed during cold acclimation, but not by drought stress in barley and wheat. Thus, it was named maize DEHYDRIN2 (ZmDhn2). It accumulates rapidly and highly in drought-stressed scutellum and leaf tissues at any stage, but not under cold stress. ZmDhn2 gene was transformed into Arabidopsis thaliana for functional analysis under drought condition. From electrolyte leakage test, no significant difference showed between wild type and transformants under normal growth condition, but the leakage level of electrolyte in wild type plants was about 3 times as high as that in the transformed plants under drought stress. It suggests that ZmDHN2 playa role in increasing drought tolerance.