A new full-length cDNA encoding strictosidine synthase (designated as OjSTR, GenBank Accession No. 1087598), which catalyzes a committed step in camptothecin biosynthetic pathway, was isolated from young leaves of Ophiorrhiza japonica for the first time. OjSTR was 1,258 bp and contained a 1,062 bp open reading frame encoding a deduced protein of 353 amino acid residues. Sequence analyses showed that OjSTR had high homology with other STRs from some TIA-producing plants. Phylogenetic tree analysis showed that OjSTR had closest relationship with STR from O. pumila. Tissue expression pattern analysis revealed that OjSTR constitutively expressed in all the tested tissues at different levels, which was high in flower, moderate in leaf and root, low in stem. Expression profiles under plant defense signals such as methyl jasmonate and salicylic acid were investigated, and the results revealed that expression of OjSTR was all induced, implying that OjSTR was high elicitor responsive.

An efficient in vitro plant regeneration system from leaves of Ophiorrhiza japonica Blume was established for the first time. Callus formation rate was more than 90.4 % from leaf segments on Murashige and Skoog (MS) supplemented with either α-naphthaleneacetic acid (NAA) alone or in combination with 6-benzyladenine (BA). The highest shoot regeneration (78.9 %) was achieved on MS medium containing 2.0 mg dm -3 BA and 0.2 mg dm -3 NAA, with an average of 9.4 shoots developed per leaf segment. Shoot regeneration was also improved when the leaf explants were cultured in MS basal medium supplemented with 0.5 % (m/v) polyvinylpyrrolidone (PVP). The leaf explants from seedlings with age of about 18 -27 d showed the highest shoot regeneration. The regenerated shoots were rooted on half-strength basal MS medium supplemented with 0.5 mg dm -3 indole-3-butyric acid (IBA), which averagely produced 24.8 roots per shoot. The plantlets were transferred to soil, where 100 % survived after 1 month of acclimatization.

The effect of introduction of the Zephyranthes grandiflora agglutinin gene (zga) to tobacco on its anti-pest ability for peach-potato aphids was investigated. PCR analysis confirmed that the zga gene was integrated into the plant genome. The results from semi-quantitative RT-PCR and real-time PCR assays revealed that the zga gene was expressed at various levels in the transgenic plants. A bioassay with aphids indicated that transgenic plants conferred enhanced resistance to aphids. Compared with the controls, the average number of aphids fed with transgenic plants during a 20-day assay evidently decreased by 70.4% in leaf disc bioassay and 77.9% in whole plant bioassay. The average number of nymph was significantly reduced by 36.4% on zga-expressing plants in leaf disc bioassay and 35.6% in whole plant bioassay. The report indicated that the introduction of zga gene to tobacco plants is a useful method to improve its anti-pest ability for aphids.

The aphid is one of the most serious pests that causes damage to crops worldwide. Lectins from Araceae plant had been proved useful to control the aphid. Herein, the full-length cDNA of Monstera deliciosa agglutinin (mda) gene was cloned and then introduced into tobacco and the influence of the expression of mda in transgenic tobacco against peach-potato aphids (Myzus persicae) was investigated. Among 92 regenerated plants, 59 positive tobacco lines were obtained. Real-time PCR assays and aphid bioassay test revealed that there is a positive correlation between the expression level of mda and the inhibitory effect on peach-potato aphids. The average anti-pests ability of mda transgenic tobacco was 74%, which was higher than that of other reported lectins from Araceae plant. These results indicated that MDA is one of promising insect resistance proteins selected for the control of peach-potato aphids.

In this paper we report on the molecular cloning, sequencing and partially characterisation of a lectin from bulb of the Chinese medicinal plant Zephyranthes grandiflora. The full-length cDNA of Z. grandiflora bulb lectin (ZGBL) consisted of 986 bp and contained a 576 bp ORF encoding a 191 amino acid protein. Bioinformatics analysis results clearly indicate that ZGBL belongs to the monocot mannose-binding lectin family, which contains 3 putative mannose-binding sites per subunit. RT-PCR analysis results indicate that ZGBL is constitutively expressed in all the tested tissue types including root, bulb, leaf and flower. Interestingly, ZGBL is more closely related to the Orchidaceae rather than the Amaryllidaceae family on molecular evolution.