The identity of Ceropegia hirsuta in Thailand has been questioned. Although this plant is quite similar to the original C. hirsuta from India, being entirely hirsute, with yellowishshaded flowers, a curved, funnel-shaped corolla tube, and broad corolla lobes shorter than the corolla tube, there are several clear differences in morphological traits between the materials collected in Thailand and the type and further specimens collected in India. Moreover, C. hirsuta s.s. is restricted to Peninsular India. In this study, using molecular phylogenetic analysis based on DNA sequence data for ITS (nuclear) and trnT-L, trnL, and trnL-F (all cpDNA) markers, and classical morphology-based delineation, we demonstrate that the plant from Thailand represents a species on its own clearly separated from C. hirsuta s.s. as well as from all other known congeners. Therefore, we here describe it as a new species, C. citrina.A detailed description, illustrations, and photographs are provided, together with a comparison of morphological traits of C. citrina, C. hirsuta and another Thai species, C. foetidiflora. We also provide characterization of floral volatile compounds and pollinators.Our study emphasizes that morphological convergence may lead to errors in taxonomic treatment within the genus Ceropegia, and that phylogenetic relationships are largely congruent with geographic distribution.

The preparation of water-blown rigid polyurethane (RPUR) foams using bio-based polyols from sesame seed oil and pumpkin seed oil has been reported. Polyols synthesis involved two steps, namely, hydroxylation and alcoholysis reaction. FTIR, NMR, and ESI-MS were used to monitor the process of the synthesized polyols and their physicochemical properties were determined. The resulting polyols have OH number in the range of 340–351 mg KOH/g. RPUR foams blown with water were produced from the reaction of biopolyols with commercial polymeric methylene diphenyl diisocyanate (PMDI). The proper PUR formulations can be manipulated to produce the desired material applications. These seed oil-based RPUR foams exhibited relatively high compressive strength (237.7–240.2 kPa) with the density in the range of 40–45 kg/m3. Additionally, the cell foam morphology investigated by scanning electron microscope indicated that their cellular structure presented mostly polygonal closed cells. The experimental results demonstrate that these bio-based polyols can be used as an alternative starting material for RPUR production.

Possession of flowers that trap fly pollinators is a conservative trait within the genus Ceropegia, in which pollination systems can be generalized or highly specialized. However, little is known about the role of plant–pollinator interactions in the maintenance of species boundaries. This study examined the degree of plant–pollinator specialization and identified the parameters responsible for specificity among four co-occurring Ceropegia species with overlapping flowering times. All investigated plant species were functionally specialized on pollination by Chloropidae and/or Milichiidae flies and each Ceropegia species was, in turn, ecologically highly specialized on only two pollinating fly morphospecies, though one plant species appeared more generalist. Species-specific fly attraction was due to the differences between plant species in floral scents, floral morphology, colour patterns, and presence of other functional structures, e.g., vibratile trichomes, which were shown to contribute to pollinator attraction in one study species. The combination of these olfactory and visual cues differentially influenced pollinator preferences and thus hindered heterospecific visitation. Furthermore, a pollinator exchange experiment also highlighted that species integrity is maintained through efficient ethological isolation (pollinator attraction). The mechanical isolation mediated by the fit between floral morphology and size and/or shape of fly pollinators appears less pronounced here, but whether or not the morphological match between male (pollinium) and female (guide rails) reproductive organs can impede hybridization remains to be investigated.

Possession of flowers that trap dipteran pollinators is a phylogenetically conserved trait within the genus Ceropegia, in which pollination systems can be generalized or highly specialized. However, little is known about the role of plant–pollinator interactions in maintaining reproductive isolation between plant species. This study examined the degree of specificity in plant-pollinator interactions and identified the mechanisms responsible for specificity among four synchronopatric species of Ceropegia. These species showed significant differences in floral scents, floral morphology, colour patterns, and presence of other functional structures, e.g., vibratile trichomes, whose essential role in fly attraction was experimentally demonstrated here. Similarity in chemical compositions of the floral scents to that of crushed Cletus trigonus bugs living in the same habitat suggests kleptomyiophily in at least some of the species studied. This is the first study to empirically demonstrate that mechanical isolation plays no discernable part in floral isolation in Ceropegia, but instead that a combination of olfactory and visual cues differentially influenced pollinator preferences and hindered heterospecific visitation, ensuring specificity through pollinator constancy, thereby driving ethological isolation among these congeneric sympatric species. We also showed experimentally that specificity was not maintained outside these plants’ native range, where other fly species occur.

In addition to white jasmine rice, Thailand has many native-colored rice varieties with numerous health benefits and the potential to become a global economic crop. However, the chemical characteristics of aromatic substances in native-colored rice are still mostly unknown. This study aimed to identify the key volatile aroma compounds and the biosynthetic pathways possibly involved in their formation in Thai native-colored rice varieties, and thus leading to the search for potential genetic markers for breeding colored rice with better aromatic properties. Twenty-three rice varieties in four categories: aromatic white, aromatic black, non-aromatic black, and non-aromatic red, were investigated (n=10 per variety). Seed husks were removed before the analysis of rice volatile aromas by static headspace gas chromatography–mass spectrometry. Untargeted metabolomics approach was used to discover the key volatile compounds in colored rice. Forty-eight compounds were detected. Thirty-eight of the 48 compounds significantly differed among groups at p<0.05, 28 of which at p<0.0001, with the non-aromatic black and red rice containing much lower content of most volatile constituents than the aromatic black and white rice. Focusing on the aromatic black rice, the samples appeared to contain high level of both compound groups of aldehydes (3-methylbutanal, 2-methylbutanal, 2-methylpropanal, pentanal, hexanal) and alcohols (butane-2,3-diol, pentan-1-ol, hexan-1-ol). Biosynthetically, these distinctive black-rice volatile compounds were proposed to be formed from the metabolic degradation of branched-chain amino acids (L-leucine, L-isoleucine and L-valine) and polyunsaturated fatty acids (linoleic acid and α-linolenic acid), involving the branched-chain aminotransferases and keto-acid decarboxylases and the 9-lipoxygonases and 13-lipoxygeases, respectively. The proposed degradative pathways of amino acids and fatty acids were well agreed with the profiles key volatile compounds detected in the Thai native-colored rice varieties.