AaABCG20 transporter involved in cutin and wax secretion affects the initiation and development of glandular trichomes in Artemisia annua.

Glandular trichomes are specialized structures found on the surface of plants to produce specific compounds, including terpenes, alkaloids, and other organic substances. Artemisia annua, commonly known as sweet wormwood, synthesizes and stores the antimalarial drug artemisinin in glandular trichomes. Previous research indicated that increasing the glandular trichome density could enhance artemisinin production, and the cuticle synthesis affected the initiation and development of glandular trichomes in A. annua. In this study, AaABCG12 and AaABCG20 were isolated from A. annua that exhibited similar expression patterns to artemisinin biosynthetic genes. Of the two, AaABCG20 acted as a specific transporter in glandular trichomes. Downregulating the expression of AaABCG20 resulted in a notable reduction in the density of glandular trichome, while overexpressing AaABCG20 resulted in an increase in glandular trichome density. GC-MS analysis demonstrated that AaABCG20 was responsible for the transport of cutin and wax in A. annua. These findings indicated that AaABCG20 influenced the initiation and development of glandular trichomes through transporting cutin and wax in A. annua. This glandular trichome specific half-size ABCG-type transporter is crucial in facilitating the transportation of cutin and wax components, ultimately contributing to the successful initiation and development of glandular trichomes.

Examination of camptothecin and 10-hydroxycamptothecin in Camptotheca acuminata plant and cell culture, and the affected yields under several cell culture treatments

Camptothecin and its derivatives are monoterpenoid indole alkaloids exhibiting significant anti-tumor actions. With the aim of improving the production of these pharmaceuticals, the contents of camptothecin and 10-hydroxycamptothecin in different tissues including roots, stems, leaves, young flower buds, opening flowers, fading flowers and seeds from Camptotheca acuminata, were investigated. The young flower buds had the highest alkaloid concentrations (camptothecin, 2.46 mg/g of dry weight; 10-hydroxycamptothecin, 1.41 mg/g of dry weight). Callus showed lower concentrations but it should also be considered as a potential source of these pharmaceuticals. In the present study, the growth rate of Camptotheca acuminata cells in culture did not correlate with contents of camptothecin and 10-hydroxycamptothecin. Alkalo id accumulation by cells under various treatments (heavy metal ions, UV-B), methyl-jasmonate, abscisic acid, salicylic acid and hydrogen peroxide was examined, and the most notable effects appeared in the cells induced by UV-B light (which showed an 11-fold increase in camptothecin concentration) and by salicylic acid (which showed a 25-fold increase in 10-hydroxycamptothecin concentration). These results are significant in the context of the production of both pharmaceuticals.

Genomic cloning and characterization of a PPA gene encoding a mannose-binding lectin from Pinellia pedatisecta

A gene encoding a mannose-binding lectin, Pinellia pedatisecta agglutinin (PPA), was isolated from leaves of Pinellia pedatisecta using genomic walker technology. The ppa contained an 1140-bp 5'-upstream region, a 771-bp open reading frame (ORF) and an 829-bp 3'-downstream region. The ORF encoded a precursor polypeptide of 256 amino acid residues with a 24-amino acid signal peptide. There were one putative TATA box and six possible CAAT boxes lying in the 5'-upstream region of ppa. The ppa showed significant similarity at the nucleic acid level with genes encoding mannose-binding lectins from other Araceae species such as Pinellia ternata, Arisaema heterophyllum, Colocasia esculenta and Arum maculatum. At the amino acid level, PPA also shared varying homology (ranging from 40% to 85%) with mannose-binding lectins from other plant species, such as those from Araceae, Alliaceae, Iridaceae, Lillaceae, Amaryllidaceae and Bromeliaceae. The cloning of the ppa gene not only provides a basis for further investigation of PPA's structure, expression and regulation mechanism, but also enables us to test its potential role in controlling pests and fungal diseases by transferring the gene into tobacco and rice in the future

Molecular cloning and characterization of a novel mannose-binding lectin cDNA from Zantedeschia aethiopica

Using RNA extracted from Zantedeschia aethiopica young leaves and primers designed according to the conservative regions of Araceae lectins, the full-length cDNA of Z. aethiopica agglutinin (ZAA) was cloned by rapid amplification of cDNA ends (RACE). The full-length cDNA of zaa was 871 bp and contained a 417 bp open reading frame (ORF) encoding a lectin precursor of 138 amino acids. Through comparative analysis of zaa gene and its deduced amino acid sequence with those of other Araceae species, it was found that zaa encoded a precursor lectin with signal peptide. Secondary and three-dimensional structure analyses showed that ZAA had many common characters of mannose-binding lectin superfamily and ZAA was a mannose-binding lectin with three mannose-binding sites. Southern blot analysis of the genomic DNA revealed that zaa belonged to a multi-copy gene family