cDNA Fragment Cloning of L-Galactono-1,4-Lactone Dehydrogenase andIt＇s Expression in Different Organs of R. roxburghii Tratt

A 855 bp cDNA encoding L-galactono-1,4-lactone dehydrogenase (GalLDH) fragment was cloned from fruit of R. roxburghii Tratt by the method of RT-PCR, on the basis of the homologous genes of Arabidopsis thaliana, cauliflower, sweet potato, strawberry, etc. in GenBank. Sequence analysis showed 79-92% identity in nucleotide sequence and 75-87% identity in amino acid sequence to that of strawberry and Arabidopsis thaliana, etc. Northern blot showed that the expression of GalLDH was significantly different in different organs. The transcription level of GalLDH in fruit was significantly higher than that in leaf, stem and root respectively. Furthermore, this expression mode was highly correlated with AsA levels.

DMAP-Catalyzed [4＋2] Cycloaddition of α,β-Unsaturated Carboxylic Acids with Ketones for Synthesis of ,β-Unsaturated δ-Lactones （pages 397–400）

The DMAP-catalyzed [4＋2] cycloaddition of α,β-unsaturated carboxylic acids with ketones furnishing α,β-unsaturated δ-lactones in good yields （up to 80%） is described, which is the first example of remote -C（sp^3）-H activation of α,β-unsaturated carboxylic acids facilitated by DMAP, a pyridine-based catalyst.

Alterations in Ascorbic Acid Levels by Transformation of the L-galactono-1,4-lactone Dehydrogenase Gene in Solanum tuberosum

L-galactono-1, 4-lactone dehydrogenase(GLDH) is an important enzyme that catalyzes the last step of the ascorbate biosynthetic pathways in plants. A full-length c DNA clone encoding GLDH was isolated from potato(Solanum tuberosum L. ‘Favorita') leaf and subcloned into a binary vector, p BI121, to construct sense and antisense recombinant plant expression vectors. The recombinants were introduced into potato via Agrobacterium-mediated transformation, and plants were confirmed as transgenic using PCR and quantitative real-time PCR. Two anti-sense potato lines(G1 and G2) and three sense lines(G3, G4 and G5) were obtained. The GLDH activity of G4 and G5 were increased in vivo. Moreover, the ascorbic acid(As A) and dehydroascorbate(DHA) contents were up-regulated in both leaves and tubers. However, the shoots of G1 were suppressed and its leaves were deformed. Additionally, the As A contents in G1 leaves and tubers decreased by 28.8% and 10.3%, respectively. The GLDH activity in leaves treated with L-galactono-1,4- lactone(L-Gal L) increased in all lines, as did the As A and DHA contents. These results indicate that GLDH activity plays an important role in regulating the As A level as well as the growth and development of potato plants.

Chemical Constituents from Fruits of Rosa davidii

From the fruit of Rosa davidii Crep., eleven compounds were isolated and identified by spectral evidence, viz. 2 alpha, 3 beta, 19 beta -trihydroxyl-olean-12-en-28-oic acid (1), 2 alpha, 3 beta -dihydroxyl-urs-28 (13)-lactone (2), arjunic acid (3), euscaphic acid (4), 2 alpha, 3 beta -dihydroxyl-urs-12-en-28-oic acid (5), oleanolic acid (6), kaempferol (7), tiliroside (8), quercetin (9), daucosterol (10) and beta -sitosterol (11). Among them, 1 and 2 were new compounds.

ESTERIFICATION ON ZEOLITES

Primary, secondary, and tertiary alcohols and polyols were esterified with carboxylic acidin the presence of HY zeolite. Yield of ester of primary alcohol is over 80 per cent, andthat of sec- and tert-alcohols, 40-50 per cent generally.γ-Lactone was synthesized byrearrangement of α- or β-octylenic to tridecylenic acid with HY zeolite.