Construction of EVA/chitosan based PEG-PCL micelles nanocomposite films with controlled release of iprodione and its application in pre-harvest treatment of grapes.

A novel nanocomposite poly(ethylene-co-vinyl acetate) (EVA) film with controlled in vitro release of iprodione (ID) was prepared. Chitosan (CS) was used as the reinforcement which enhances the water and oxygen permeability of films. ID loaded poly(ethylene glycol)-poly(ε-caprolactone) (PEG-PCL) (IPP) micelles were used as the drug carrier which endows the films with antifungal and controlled release ability. IPP micelles with spherical shape and uniform size were obtained, and the maximum encapsulation efficacy (EE) was 91.17 ± 5.03% by well controlling the feeding amount of ID. Incorporation CS could improve the oxygen and moisture permeability of films, and the maximum oxygen permeability (OP) and water vapor transmission rate (WVTR) were 477.84 ± 13.03 cc/(m2·d·0.1 MPa) and 8.60 ± 0.25 g m-2 d-1, respectively. After loading IPP micelles, the films showed an improved antifungal ability and temperature-sensitive drug release behavior, and were found to enhance the quality of grapes by pre-harvest spraying.

Species identification of medicinal pteridophytes by a DNA barcode marker, the chloroplast psbA-trnH intergenic region.

Medicinal pteridophytes are an important group used in traditional Chinese medicine; however, there is no simple and universal way to differentiate various species of this group by morphological traits. A novel technology termed "DNA barcoding" could discriminate species by a standard DNA sequence with universal primers and sufficient variation. To determine whether DNA barcoding would be effective for differentiating pteridophyte species, we first analyzed five DNA sequence markers (psbA-trnH intergenic region, rbcL, rpoB, rpoC1, and matK) using six chloroplast genomic sequences from GeneBank and found psbA-trnH intergenic region the best candidate for availability of universal primers. Next, we amplified the psbA-trnH region from 79 samples of medicinal pteridophyte plants. These samples represented 51 species from 24 families, including all the authentic pteridophyte species listed in the Chinese pharmacopoeia (2005 version) and some commonly used adulterants. We found that the sequence of the psbA-trnH intergenic region can be determined with both high polymerase chain reaction (PCR) amplification efficiency (94.1%) and high direct sequencing success rate (81.3%). Combined with GeneBank data (54 species cross 12 pteridophyte families), species discriminative power analysis showed that 90.2% of species could be separated/identified successfully by the TaxonGap method in conjunction with the Basic Local Alignment Search Tool 1 (BLAST1) method. The TaxonGap method results further showed that, for 37 out of 39 separable species with at least two samples each, between-species variation was higher than the relevant within-species variation. Thus, the psbA-trnH intergenic region is a suitable DNA marker for species identification in medicinal pteridophytes.

Identification of Dendrobium species by a candidate DNA barcode sequence: the chloroplast psbA-trnH intergenic region.

DNA barcoding is a novel technology that uses a standard DNA sequence to facilitate species identification. Although a consensus has not been reached regarding which DNA sequences can be used as the best plant barcodes, the psbA-trnH spacer region has been tested extensively in recent years. In this study, we hypothesize that the psbA-trnH spacer regions are also effective barcodes for Dendrobium species. We have sequenced the chloroplast psbA-trnH intergenic spacers of 17 Dendrobium species to test this hypothesis. The sequences were found to be significantly different from those of other species, with percentages of variation ranging from 0.3 % to 2.3 % and an average of 1.2 %. In contrast, the intraspecific variation among the Dendrobium species studied ranged from 0 % to 0.1 %. The sequence difference between the psbA-trnH sequences of 17 Dendrobium species and one Bulbophyllum odoratissimum ranged from 2.0 % to 3.1 %, with an average of 2.5 %. Our results support the notion that the psbA-trnH intergenic spacer region could be used as a barcode to distinguish various Dendrobium species and to differentiate Dendrobium species from other adulterating species.