A novel adenylate isopentenyltransferase 5 regulates shoot branching via the ATTTA motif in Camellia sinensis.

BACKGROUND: Shoot branching is one of the important agronomic traits affecting yields and quality of tea plant (Camellia sinensis). Cytokinins (CTKs) play critical roles in regulating shoot branching. However, whether and how differently alternative splicing (AS) variant of CTKs-related genes can influence shoot branching of tea plant is still not fully elucidated. RESULTS: In this study, five AS variants of CTK biosynthetic gene adenylate isopentenyltransferase (CsA-IPT5) with different 3' untranslated region (3' UTR) and 5' UTR from tea plant were cloned and investigated for their regulatory effects. Transient expression assays showed that there were significant negative correlations between CsA-IPT5 protein expression, mRNA expression of CsA-IPT5 AS variants and the number of ATTTA motifs, respectively. Shoot branching processes induced by exogenous 6-BA or pruning were studied, where CsA-IPT5 was demonstrated to regulate protein synthesis of CsA-IPT5, as well as the biosynthesis of trans-zeatin (tZ)- and isopentenyladenine (iP)-CTKs, through transcriptionally changing ratios of its five AS variants in these processes. Furthermore, the 3' UTR AS variant 2 (3AS2) might act as the predominant AS transcript. CONCLUSIONS: Together, our results indicate that 3AS2 of the CsA-IPT5 gene is potential in regulating shoot branching of tea plant and provides a gene resource for improving the plant-type of woody plants.

Suites of terpene synthases explain differential terpenoid production in ginger and turmeric tissues.

The essential oils of ginger (Zingiber officinale) and turmeric (Curcuma longa) contain a large variety of terpenoids, some of which possess anticancer, antiulcer, and antioxidant properties. Despite their importance, only four terpene synthases have been identified from the Zingiberaceae family: (+)-germacrene D synthase and (S)-ß-bisabolene synthase from ginger rhizome, and α-humulene synthase and ß-eudesmol synthase from shampoo ginger (Zingiber zerumbet) rhizome. We report the identification of 25 mono- and 18 sesquiterpene synthases from ginger and turmeric, with 13 and 11, respectively, being functionally characterized. Novel terpene synthases, (-)-caryolan-1-ol synthase and α-zingiberene/ß-sesquiphellandrene synthase, which is responsible for formation of the major sesquiterpenoids in ginger and turmeric rhizomes, were also discovered. These suites of enzymes are responsible for formation of the majority of the terpenoids present in these two plants. Structures of several were modeled, and a comparison of sets of paralogs suggests how the terpene synthases in ginger and turmeric evolved. The most abundant and most important sesquiterpenoids in turmeric rhizomes, (+)-α-turmerone and (+)-ß-turmerone, are produced from (-)-α-zingiberene and (-)-ß-sesquiphellandrene, respectively, via α-zingiberene/ß-sesquiphellandrene oxidase and a still unidentified dehydrogenase.

Production of marker-free disease-resistant potato using isopentenyl transferase gene as a positive selection marker.

The use of antibiotic or herbicide resistant genes as selection markers for production of transgenic plants and their continuous presence in the final transgenics has been a serious problem for their public acceptance and commercialization. MAT (multi-auto-transformation) vector system has been one of the different strategies to excise the selection marker gene and produce marker-free transgenic plants. In the present study, ipt (isopentenyl transferase) gene was used as a selection marker gene. A chitinase gene, ChiC (isolated from Streptomyces griseus strain HUT 6037) was used as a gene of interest. ChiC gene was cloned from the binary vector, pEKH1 to an ipt-type MAT vector, pMAT21 by gateway cloning and transferred to Agrobacterium tumefaciens strain EHA105. The infected tuber discs of potato were cultured on hormone- and antibiotic-free MS medium. Seven of the 35 explants infected with the pMAT21/ChiC produced shoots. The same antibiotic- and hormones-free MS medium was used in subcultures of the shoots (ipt like and normal shoots). Molecular analyses of genomic DNA from transgenic plants confirmed the integration of gene of interest and excision of the selection marker in 3 of the 7 clones. Expression of ChiC gene was confirmed by Northern blot and western blot analyses. Disease-resistant assay of the marker-free transgenic, in vitro and greenhouse-grown plants exhibited enhanced resistance against Alternaria solani (early blight), Botrytis cinerea (gray mold) and Fusarium oxysporum (Fusarium wilt). From these results it could be concluded that ipt gene can be used as a selection marker to produce marker-free disease-resistant transgenic potato plants on PGR- and antibiotic-free MS medium.

Farnesyl protein transferase inhibitors and other therapies targeting the Ras signal transduction pathway.

The year 2000 will be a significant date for the field of Ras-related therapies since numerous agents will have Phase II clinical efficacy data maturing to provide proof of principle for this cancer treatment strategy. These data will also provide an important milestone for the cancer research community since these molecules represent a small vanguard of oncology drug discovery projects predicated on molecular targets. We can only hope that these agents are a successful harbinger for the formidable number of targeted therapies that will be entering development pipelines in the coming years.