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Anthocyanins are major pigments responsible for the color of lily (Lilium sp.) flowers. Anthocyanin synthesis is part of the flavonoid metabolic pathway. Numerous transcription factors, including R2R3-MYBs, basic helix-loop-helix (bHLH), and tryptophan–aspartic acid repeat (also known as WD40 or WD repeat) proteins, known to regulate flavonoid biosynthesis have been identified in various plant species. However, there is limited information available on WD repeat proteins in lilies. In this study, we identified a WD repeat gene in the Oriental hybrid lily ‘Sorbonne’ (Lilium hybrid WD repeat, LhWDR). LhWDR contains no introns, and has a 1100–base pair open reading frame, encoding a putative protein of 370 amino acids. LhWDR was found to be localized in the cytoplasm of transgenic Arabidopsis thaliana root cells. Expression patterns of LhWDR in different organs and at different periods of lily tepal growth revealed that the expression levels of this gene are closely associated with anthocyanin accumulation. A yeast two-hybrid assay demonstrated that full-length LhWDR interacts with the 420 N-terminal amino acids of Lilium hybrid bHLH2. Interestingly, overexpression of LhWDR in A. thaliana led to an upregulation of the dihydroflavonol 4-reductase gene, which is an important structural gene downstream of the anthocyanin pathway. These results indicate that the WD repeat protein LhWDR might interact with a bHLH transcription factor to regulate anthocyanin biosynthesis.
Lilium cultivars have a wide range of variation in floral scent phenotypes. Using gas chromatography–mass spectrometry (GC/MS) analyses of volatile emissions during the night, the floral scent compositions of 35 lily cultivars from seven different hybrid groups were studied. The results showed that there was a positive correlation between volatile emission levels and scent intensities. Nonscented lily cultivars belonging to Asiatic hybrids hardly emitted volatiles, light-scented Longiflorum × Asiatic hybrids emitted low levels of volatiles, and scented lily cultivars (belonging to Oriental, Trumpet, Longiflorum, Longiflorum × Oriental, and Oriental × Trumpet hybrids) emitted significantly high levels of volatiles. In general, the scent compositions of lily cultivars were similar within the same hybrid group, and the differences among hybrid groups reflect their pedigree. Monoterpenoids and benzenoids dominated the floral scents of most volatile-emitting lily cultivars, whereas monoterpenoids alone dominated the floral scents of some volatile-emitting lilies. Although various scent compounds were released from volatile-emitting lily cultivars, the dominant scent compounds were focused on three monoterpenoids [1.8-cineole, linalool, and (E)-β-ocimene] and one benzenoid (methyl benzoate). The scent traits of lily cultivars could be traced back to their parents.
Wintersweet (Chimonanthus praecox) is one of the most popular winter-blooming species. Effective vegetative propagation is necessary for commercial usage and protection of wintersweet. In the current study, the four factors, namely hormone type (A), hormone concentration (B), soaking duration (C), and medium (D), were assessed using an L16 (44) orthogonal test design. The hormone types include ABT (A1), α-naphthalene acetic acid (NAA) (A2), indole butyric acid (IBA) (A3), and indole-3-acetic acid (IAA) (A4); the hormone concentrations include 100 mg·L−1 (B1), 500 mg·L−1 (B2), 1000 mg·L−1 (B3), and 1500 mg·L−1 (B4); the soaking durations include 5 seconds (C1), 5 minutes (C2), 30 minutes (C3), and 3 hours (C4); and the mediums include perlite: peat in the ratios 1:0 (D1), 2:1 (D2), 1:1 (D3), and 1:2 (D4). The results showed that hormone and proper medium could significantly improve the cutting survival, rooting, and sprouting, whereas poor factor combinations, especially high hormone concentrations combined with long soaking durations may be threatened to the cuttings and rooting. In actual experiments, we successfully obtained an excellent rooting percentage (62.22%) of wintersweet from treatment No. 5 (A2B1C2D3), which is perlite and peat (1:1) as the medium and soaking the cuttings in 100 mg·L−1 NAA for 5 minutes as the hormone treatment. This combination can already meet the requirements for commercial production. A range analysis showed that the medium and hormone concentration were the most important factors affecting the cutting of wintersweet. An analysis of variance also showed that the medium and hormone concentration can significantly or extremely significantly affect most cutting indicators. Moreover, our results revealed that an orthogonal design method is an effective tool for establishing an improved technique for cutting propagation.