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Liparis gigantea generally grows in subtropical broad-leaved evergreen forests and blooms during the rainy season with purple flowers. Our study focused on floral phenology and morphology, pollinators and their behavior, and pollination mechanism. Our observations showed that the population flowering period lasted for about 20 days, and the single flowering period was 5–6 days. The rate of artificial self-pollination was 100%, which indicated that L. gigantea was self-compatible. L. gigantea achieved reproduction success by attracting Mycomya sp. (Diptera, Mycetophilidae). There was no significant difference between pollination efficiency both at night and during the day (Premoval = 0.34, Pdeposition = 0.55). Data on the functional morphological characteristics of L. gigantea and the pollinators related to pollination showed a high match, with the height and width of the pollination tunnel were 3.10 ± 0.34 and 1.93 ± 0.22 mm, and the height and width of the pollinator's thorax were 5.84 ± 0.96 and 0.96 ± 0.23 mm. The forefoot of insects could be stretched and bent when visiting flowers, so that they could exactly enter and exit the flower with removing or depositing pollinia. While L. gigantea could be pollinated by Mycomya sp., it could also be self-pollinated with the aid of rain. With the assistance of raindrops, the pollinia of L. gigantea slowly slid to the stigma. And this rain-assisted self-pollination mechanism guaranteed the success of reproduction in L. gigantea, especially in the special habitat and flowering season. The results of our study indicated that L. gigantea had a complex pollination reproduction system for insect and rain pollination. [ABSTRACT FROM AUTHOR]

Dendrobium nestor is a famous orchid species in the Orchidaceae family. There is a diversity of flower colorations in the Dendrobium species, but knowledge of the genes involved and molecular mechanism underlying the flower color formation in D. nestor is less studied. Therefore, we performed transcriptome profiling using Illumina sequencing to facilitate thorough studies of the purple color formation in petal samples collected at three developmental stages, namely—flower bud stage (F), half bloom stage (H), and full bloom stage (B) in D. nestor. In addition, we identified key genes and their biosynthetic pathways as well as the transcription factors (TFs) associated with purple flower color formation. We found that the phenylpropanoid–flavonoid–anthocyanin biosynthesis genes such as phenylalanine ammonia lyase, chalcone synthase, anthocyanidin synthase, and UDP-flavonoid glucosyl transferase, were largely up-regulated in the H and B samples as compared to the F samples. This upregulation might partly account for the accumulation of anthocyanins, which confer the purple coloration in these samples. We further identified several differentially expressed genes related to phytohormones such as auxin, ethylene, cytokinins, salicylic acid, brassinosteroid, and abscisic acid, as well as TFs such as MYB and bHLH, which might play important roles in color formation in D. nestor flower. Sturdy upregulation of anthocyanin biosynthetic structural genes might be a potential regulatory mechanism in purple color formation in D. nestor flowers. Several TFs were predicted to regulate the anthocyanin genes through a K-mean clustering analysis. Our study provides valuable resource for future studies to expand our understanding of flower color development mechanisms in D. nestor. [ABSTRACT FROM AUTHOR]

• Habenaria rhodocheila is pollinated by the swallowtail butterfly Papilio helenus • H. rhodocheila is self-compatible, but depends on P. helenus for pollination • The insect proboscis length is similar to the spur length, but slightly shorter • During pollination, the pollinarium is attached to the base of the proboscis • H. rhodocheila appears adapted for specialized pollination by P. helenus Habenaria rhodocheila is different from other species in the genus as it has bright yellow-orange, orange-red or red floral colors and grows in subtropical evergreen broad-leaved forests. It is listed as a level II protected plant in China. This study focused on details of the pollination mechanism, including floral structure, the pollinator and its behavior, the pollination process, and fruit set in its natural environment compared to controlled artificial pollination. Our results showed that the flowers of H. rhodocheila are self-compatible, but rely on a pollinating agent due to the lack of an automatic self-pollination mechanism. At three sites the flowers of H. rhodocheila were frequently pollinated by a species of the swallowtail butterfly Papilio helenus L. During pollination, the butterfly inserts its proboscis into the spur aperture. The base of the proboscis then contacts the viscidia and the pollinarium sticks to the insect, followed by contact between pollinia and stigmas. The length of the proboscis of P. helenus is comparable to, but slightly shorter than the length of the floral spur. The pollination activity generally occurs between 9:30 AM to 1:30 PM daily and is especially frequent between 10:30 AM and 11:30 AM. These results suggest that the similarity between the length of the butterfly's proboscis and the length of the orchid's spur is a major factor contributing to the efficient pollination of H. rhodocheila in its natural habitat. Most species in Habenaria are moth-pollinated, whereas our research has shown that H. rhodocheila in subtropical evergreen broad-leaved forests in China is specifically adapted to butterfly pollination by P. helenus. [ABSTRACT FROM AUTHOR]