Hybrid Lily Research Articles

Isolation and identification of MYB transcription factors (MYB19Long and MYB19Short) involved in raised spot anthocyanin pigmentation in lilies (Lilium spp.)

Although anthocyanin color patterns on flowers are among the most attractive characteristics, the genetic mechanisms through which color patterns are developed are not well understood, especially for color patterns associated with altered petal structure. Lilium species and cultivars often develop raised spots, where the interior surfaces of tepals increase to develop bumps with accompanying anthocyanin accumulation. The aim of this study was to identify transcription factors regulating pigmentation of the bumps. We identified two R2R3-MYB genes, MYB19Long and MYB19Short, in Lilium leichtlinii, L. lancifolium, and Asiatic hybrid lily cultivars. Their amino acid sequences were similar; however, part of the C-terminal region was triplicated in MYB19Long. Spatial and temporal expression profiles in lilies were strongly associated with anthocyanin biosynthesis gene expression in the bumps, and some defects were found in these genes in L. lancifolium ‘Pure Gold’ that developed colorless bumps. Thus, both MYB19Long and MYB19Short were likely to be involved in the bump pigmentation. MYB19Long had a stronger ability to stimulate target gene expression than MYB19Short, and expression levels of MYB19Long were greater than those of MYB19Short in lily tepals; thus, the ability to biosynthesize anthocyanin pigments was greater for MYB19Long than for MYB19Short. Among the F1 population, MYB19Short expression was found only in the tepals of F1 plants that developed bumps, although all of the F1 plants possessed the MYB19Short gene, indicating that MYB19 expression followed bump development. These findings helped to elucidate the genetic mechanisms underlying raised spot development.

Transcriptome Analysis of Carbohydrate Metabolism Genes and Molecular Regulation of Sucrose Transport Gene LoSUT on the Flowering Process of Developing Oriental Hybrid Lily 'Sorbonne' Bulb.

The quality of Lily cut flower was determined by the quality of bulbs. During the process of vernalization and flower bud differentiation, sugar massively accumulated in the bulb, which influenced the bulb development. However, the details of sugar genes’ regulation mechanism for these processes were not fully understood. Here, morphological physiology, transcriptomes and gene engineering technology were used to explore this physiological change. Seventy-two genes of 25 kinds of sugar metabolism-related genes were annotated after re-analyzing transcriptome data of Oriental hybrid lily ‘Sorbonne’ bulbs, which were generated on Hiseq Illumina 2000. The results showed that these genes were closely related to lily bulb vernalization and development. Combining gene expression pattern with gene co-expression network, five genes (Contig5669, Contig13319, Contig7715, Contig1420 and Contig87292) were considered to be the most potential signals, and the sucrose transporter gene (SUT) was the focus of this study. Carbohydrate transport pathway and genes’ regulation mechanism were inferred through a physiological and molecular test. SUT seemed to be the sugar sensor that could sense and regulate sugar concentration, which might have effects on other genes, such as FT, LFY and so on. LoSUT2 and LoSUT4 genes were cloned from Oriental hybrid lily ‘Sorbonne’ by RACE, which was the first time for these genes in Oriental hybrid lily ‘Sorbonne’. The physiological properties of these proteins were analyzed such as hydrophobicity and phosphorylation. In addition, secondary and tertiary structures of proteins were predicted, which indicated the two proteins were membrane proteins. Their cellular locations were verified through positioning the experiment of the fluorescent vector. They were highly expressed in cells around phloem, which illustrated the key role of these genes in sugar transport. Furthermore, transient expression assays showed that overexpressed LoSUT2 and LoSUT4 in Arabidopsis thaliana bloomed significantly earlier than the wild type and the expression of FT, SOC1 and LFY were also affected by LoSUT2 and LoSUT4, which indicated that LoSUT2 and LoSUT4 may regulate plants flowering time.

Cloning and Functional Characterization of a Flavonoid Transport-Related MATE Gene in Asiatic Hybrid Lilies (Lilium spp.).

Previous studies have suggested that multidrug and toxic compound extrusion (MATE) proteins might be involved in flavonoid transportation. However, whether MATE proteins are involved in anthocyanin accumulation in Lilium is unclear. Here, a flavonoid transport-related MATE candidate gene, LhDTX35, was cloned from the Asiatic hybrid lily cultivar ‘Tiny Padhye’ by rapid amplification of 5’ and 3’ cDNA ends (RACE) and found to encode 507 amino acids. BLASTx results indicated that LhDTX35 showed high homology to the DTX35 genes of other species. Bioinformatics analysis predicted that the protein encoded by LhDTX35 possessed 12 typical transmembrane segments and had functional domains typical of the MATE-like superfamily. Phylogenetic analysis grouped LhDTX35 in the same clade as the DTX35 of other species. Notably, the expression pattern of LhDTX35 was positively correlated with floral anthocyanin accumulation in ‘Tiny Padhye’. A subcellular localization assay showed that the protein encoded by LhDTX35 was plasmalemma localized but not nuclear, indicating that the LhDTX35 gene may function as a carrier protein to transport anthocyanins in Lilium. Functional complementation of the Arabidopsis DTX35 gene demonstrated that LhDTX35 could restore silique-infertility and the anthocyaninless phenotype of an Arabidopsis DTX35 mutant. These results indicated that LhDTX35 might be involved in anthocyanin accumulation in Lilium.

Overexpression of LiTPS2 from a cultivar of lily (Lilium ‘Siberia’) enhances the monoterpenoids content in tobacco flowers

Lily, a famous cut flower with highly fragrance, has high ornamental and economic values. Monoterpenes are the main components contributing to its fragrance, and terpene synthase (TPS) genes play critical roles in the biosynthesis of monoterpenoids. To understand the function of TPS and to explore the molecular mechanism of floral scent in cultivar Lilium ‘Siberia’, transcriptomes of petal at different flowering stages and leaf were obtained by RNA sequencing and three unigenes related to TPS genes were selected for further validation. Quantitative real-time PCR showed that the expression level of LiTPS2 was greater than that of the other two TPS genes. Phylogenetic analysis indicated that LiTPS2 belonged to the TPSb subfamily, which was responsible for monoterpenes synthesis. Subcellular localization demonstrated that LiTPS2 was located in the chloroplasts. Furthermore, functional characterization showed that LiTPS2 utilized both geranyl pyrophosphate (GPP) and farnesyl pyrophosphate (FPP) to produce monoterpenoids such as linalool and sesquiterpenes like trans-nerolidol, respectively. Ectopic expression in transgenic tobacco plants suggested that the amount of linalool from the flowers of transgenic plants was 2–3 fold higher than that of wild-type plants. And the emissions of myrcene and (E)-β-ocimene were also accumulated from the flowers of LiTPS2 transgenic lines. Surprisingly, these three compounds were the main fragrance components of oriental lily hybrids. Our results indicated that LiTPS2 contributed to the production of monoterpenes and could effectively regulate the aroma of Lilium cultivars, laying the foundation for biotechnological modification of floral scent profiles.

Cloning and Characterization of a Tryptophan–Aspartic Acid Repeat Gene Associated with the Regulation of Anthocyanin Biosynthesis in Oriental Hybrid Lily

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.

Investigation of the morphological and cytogenetic variations of an intraspecific Asiatic lily hybrid using 5S and 18S rDNA probes

This study aimed to determine the morphological and cytogenetic differences in an intraspecific Asiatic F1Lilium hybrid. The results indicated that leaf color and shape, flower morphology including color, spot size on petal, and filament color in the F1 hybrid showed significant variations as compared to parents, while days to flowering were similar to those of the parents. Moreover, stem height, leaf number, and leaf width showed distinct variations. Interestingly, the intraspecific F1 progeny obtained from Asiatic lily parents showed higher pollen viability. In addition, FISH results revealed significant variation in the number of 18S rDNA and 5S rDNA loci identified in both parents and the F1 progeny. The female (2n = 4x = 48) parent had 12 loci of 18S rDNA, whereas the male (2n = 2x = 24) parent and the F1 (2n = 3x = 36) had 8 and 11 loci of 18S rDNA, respectively. Moreover, the F1 progeny had 9 loci of 5S rDNA compared with the 7 and 4 loci identified in the female and male parents, respectively. All 5S rDNA signals were observed on the long arm in both the female parent and the F1; however, one 5S rDNA signal was observed on the short arm in the male parent. Therefore, this study demonstrated that the distribution of ribosomal DNA was greatly different in the F1 progeny than that of parents.

Transcriptomic and proteomic analysis reveals mechanisms of low pollen-pistil compatibility during water lily cross breeding

BackgroundIn water lily (Nymphaea) hybrid breeding, breeders often encounter non-viable seeds, which make it difficult to transfer desired or targeted genes of different Nymphaea germplasm. We found that pre-fertilization barriers were the main factor in the failure of the hybridization of Nymphaea. The mechanism of low compatibility between the pollen and stigma remains unclear; therefore, we studied the differences of stigma transcripts and proteomes at 0, 2, and 6 h after pollination (HAP). Moreover, some regulatory genes and functional proteins that may cause low pollen-pistil compatibility in Nymphaea were identified.ResultsRNA-seq was performed for three comparisons (2 vs 0 HAP, 6 vs 2 HAP, 6 vs 0 HAP), and the number of differentially expressed genes (DEGs) was 8789 (4680 were up-regulated), 6401 (3020 were up-regulated), and 11,284 (6148 were up-regulated), respectively. Using label-free analysis, 75 (2 vs 0 HAP) proteins (43 increased and 32 decreased), nine (6 vs 2 HAP) proteins (three increased and six decreased), and 90 (6 vs 0 HAP) proteins (52 increased and 38 decreased) were defined as differentially expressed proteins (DEPs). Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analyses revealed that the DEGs and DEPs were mainly involved in cell wall organization or biogenesis, S-adenosylmethionine (SAM) metabolism, hydrogen peroxide decomposition and metabolism, reactive oxygen species (ROS) metabolism, secondary metabolism, secondary metabolite biosynthesis, and phenylpropanoid biosynthesis.ConclusionsOur transcriptomic and proteomic analysis highlighted specific genes, incuding those in ROS metabolism, biosynthesis of flavonoids, SAM metabolism, cell wall organization or biogenesis and phenylpropanoid biosynthesis that warrant further study in investigations of the pollen-stigma interaction of water lily. This study strengthens our understanding of the mechanism of low pollen-pistil compatibility in Nymphaea at the molecular level, and provides a theoretical basis for overcoming the pre-fertilization barriers in Nymphaea in the future.

White with partially pink flower color in Lilium cernuum var. album is caused by transcriptional regulation of anthocyanin biosynthesis genes

Lilium cernuum is among the most important wild species used for the breeding of Asiatic hybrid lilies. Two flower-color types are included in L. cernuum: the entire tepals are pink in the selected common type, whereas var. album flowers develop white tepals with partially pink regions. To understand the mechanisms creating the white with partially pink tepals, expression of genes related to anthocyanin biosynthesis was investigated. Although the amounts of anthocyanin pigments were considerably lower in the tepals of var. album than in those of the common type, they both expressed the identical LcMYB12 transcription factor gene. We found this gene to positively regulate the expression of anthocyanin biosynthesis genes in the transient assay (agroinfiltration) using tobacco leaves. Expression levels of LcMYB12 and anthocyanin biosynthesis genes were lower in var. album than in the common type. Thus, down-regulation of LcMYB12 expression is likely to be the main reason for the creation of the white with partially colored tepals. The var. album also possessed a non-functional allele of LcMYB12, LcMYB12-del, in which the C-terminal region was truncated. However, the segregation analysis conducted using F1 plants derived from the crosses between the common type and var. album indicated that LcMYB12-del expression was not correlated with tepal colors. Lilium cernuum developed tiny spots at the base of its tepals. In addition to LcMYB12, LcMYBSPLATTER was expressed at the spot-containing tepal region. Because the LcMYBSPLATTER sequence was very similar to the sequence of LhMYBSPLATTER (formerly LhMYB12-Latvia) regulating the pigmentation at splatter-type anthocyanin spots, LhMYBSPLATTER in Asiatic hybrid lilies is likely to have been derived from L. cernuum.

QTLs position of some important ornamental traits in recently developed OO lily population.

Lilium L. is a perennial ornamental bulbous species, belonging to Liliaceae family, which consists of about 100 species. One of the most important hybrids in Lilium L. is the Oriental hybrid lily. Different cross combinations have been done in the lily family such as AA (Asiatic × Asiatic), AL (Asiatic × Longiflorum), and OT (Oriental × Trumpet). The OO (Oriental × Oriental) combination is a new one. SSR and AFLP markers were used to overlap each other and the genetic linkage groups were created according to the haploid number of lily chromosomes (12 linkage groups). In this experiment, the final F1 population, which creates a genetic linkage group, was 100 individuals. For map construction, JOINMAP 4.0 software by treating segregation data of markers as a CP (out breeder full-sib family) model was used. After evaluation of ornamental traits, MapQTL 4.0 software was also used to find possible QTLs on these linkage maps. A total of 940 primers were tested and the best ones, which were 172 primer pairs (96 AFLP and 76 SSR markers), were used for map construction and the total of 616 loci (465 loci for AFLP marker and 151 loci for SSR marker) were scored. The entire mapped length was 2144.2cM. 8 QTLs were obtained for flower number which is an important trait in lily. Each QTL locus explained the phenotypic variation of 2.4-89.5%. The highest amount of LOD (35.21) was found in LG-F1P2 for FN4 QTL. For leaf number, one-QTL was mapped with LOD of 7.08 between 2 markers on the LG-M10 of maternal maps. The QTL for petal length was placed on the LG-F1P2 of the F1 hybrid maps on the E-CGC/M-CGC-4 primer combination. The petal width QTLs also were mapped on the E-CGC/M-CGC-4. Qualitative locus named LN was mapped on the LG-M10 of the maternal maps. PW2 QTL was also localized on the LG-F4 of the paternal maps. In this experiment, 5 QTLs also were mapped for spot number in all F1 hybrids and paternal and maternal maps, and spot size. Moreover, one QTL with the length of 51cM was measured on the LG-M8 of the maternal maps. Plant height QTL with the LOD of 12.54 was mapped on the primer combination of E-CGC/M-CGC-4 on the LG-F1P2 of the F1 hybrid maps.

Effect of light condition and height of flower harvesting on bulb and bulblet production in Asiatic hybrid lily

Effect of light condition and height of flower harvesting on bulb and bulblet production in Asiatic hybrid lily

The complete chloroplast genome of a rare species in Korea, Lilium Dauricum Ker Gawl

Lilium dauricum Ker Gawler is a wild lily species that belongs to section Sinomartagon and is one of the ancestors of the Asiatic hybrid lilies. Unique traits such as disease resistance and early flowering make L. dauricum a desirable resource for interspecific hybridization. However, in Korea, the natural resources of L. dauricum are being exhausted by excessive exploitation and require urgent conservation. In this study, the complete chloroplast genome of L. dauricum was generated using Illumina paired-end sequencing technology, and its structure was compared with that of other Lilium species. The chloroplast genome was 152,063 bp long, with a typical quadripartite structure including a pair of inverted repeat regions (26,492 bp) separated by a large (81,485 bp) and small (17,584 bp) single-copy (SC) region. The genome encodes 131 different genes, including 85 protein-coding genes, 38 tRNA genes, and 8 rRNA genes. A phylogenetic analysis strongly supported the relationship of L. dauricum with other members of Sinomartagon and Martagon lilies.

Transcriptional Regulatory Network of GA Floral Induction Pathway in LA Hybrid Lily.

Background: The LA hybrid lily ‘Aladdin’ has both excellent traits of Longiflorum hybrids and Asiatic hybrids—such as big and vivid flower, strong stem, high self-propagation coefficient, and shorter low temperature time required to release bulb dormancy in contrast to Oriental hybrids. A genome-wide transcriptional analysis using transcriptome RNA-Seq was performed in order to explore whether there is a gibberellin floral induction pathway in the LA hybrid lily. Subsequently, gene co-expression network analysis was used to analyze the possible interactions of key candidate genes screened from transcriptome data. At the same time, a series of physiological, biochemical, and cultivation tests were carried out. Results: The content of five endogenous hormones changed sharply in the shoot apex during the treatment of 200 mg/L exogenous gibberellin and the ratio of ABA/GA3 dropped and stayed at a lower level after 4 hours’ treatment from the higher levels initially, reaching a dynamic balance. In addition, the metabolism of carbohydrates in the bulbs increase during exogenous gibberellin treatment. A total of 124,041 unigenes were obtained by RNA-seq. With the transcriptome analysis, 48,927 unigenes and 48,725 unigenes respectively aligned to the NR database and the Uniprot database. 114,138 unigenes, 25,369 unigenes, and 19,704 unigenes respectively aligned to the COG, GO, and KEGG databases. 2148 differentially expression genes (DEGs) were selected with the indicators RPKM ≥ 0, FDR ≤ 0.05 and |log2(ratio)| ≥ 2. The number of the upregulated unigenes was significantly more than the number of the downregulated unigenes. Some MADS-box genes related to flowering transformation—such as AGL20, SOC1, and CO—were found to be upregulated. A large number of gibberellin biosynthesis related genes such as GA2ox, GA3ox, GA20ox, Cytochrome P450, CYP81, and gibberellin signal transduction genes such as DELLA, GASA, and GID1 were significantly differentially expressed. The plant hormones related genes such as NCED3 and sugar metabolism related genes such as α-amylase, sucrose synthase hexokinase, and so on were also found expressing differentially. In addition, stress resistance related genes such as LEA1, LEA2, LEA4, serine/threonine protein kinase, LRR receptor-like serine/threonine protein kinase, P34 kinase, histidine kinase 3 and epigenetic related genes in DNA methylation, histone methylation, acetylation, ubiquitination of ribose were also found. Particularly, a large number of transcription factors responsive to the exogenous gibberellin signal including WRKY40, WRKY33, WRKY27, WRKY21, WRKY7, MYB, AP2/EREBP, bHLH, NAC1, NAC2, and NAC11 were found to be specially expressing. 30 gene sequences were selected from a large number of differentially expressed candidate genes for qRT-PCR expression verification (0, 2, 4, 8, and 16 h) and compared with the transcriptome expression levels. Conclusions: 200mg/L exogenous GA3 can successfully break the bulb’s dormancy of the LA hybrid lily and significantly accelerated the flowering process, indicating that gibberellin floral induction pathway is present in the LA lily ‘Aladdin’. With the GCNs analysis, two second messenger G protein-coupled receptor related genes that respond to gibberellin signals in the cell were discovered. The downstream transport proteins such as AMT, calcium transport ATPase, and plasma membrane ATPase were also discovered participating in GA signal transduction. Transcription factors including WRKY7, NAC2, NAC11, and CBF specially regulated phosphorylation and glycosylation during the ubiquitination degradation process of DELLA proteins. These transcription factors also activated in abscisic acid metabolism. A large number of transcription factors such as WRKY21, WRKY22, NAC1, AP2, EREB1, P450, and CYP81 that both regulate gibberellin signaling and low-temperature signals have also been found. Finally, the molecular mechanism of GA floral induction pathway in the LA hybrid lily ‘Aladdin’ was constructed.

Morphological characterization of interspecific lily hybrids with multiple flower stalks derived from Lilium concolor Salisb. var. mutsuanum Makino

Lilium concolor Salisb. var. mutsuanum Makino can produce multiple flower stalks from the same bulb, and our ultimate goal is to develop new lily cultivars with this unique trait. Interspecific crosses of L. concolor var. mutsuanum and the Asiatic lily hybrid 'Avignon' were carried out with intrastylar pollination and ovule culture, and 49 hybrid strains were acquired. In this study, morphological characterization of the flowering of 46 hybrid strains was performed in the third year after acclimation. Fifteen hybrid strains produced one stalk per bulb, 10 hybrid strains produced two stalks per bulb and five hybrid strains produced three stalks per bulb, and the strains with the most stalks per bulb had nine stalks. The hybrid strains with a large number of stalks per bulb had lower plant height, thinner stalks, and fewer flowers per stalk. There was no significant correlation between the number of stalks per bulb and the number of flowers per bulb or flower diameter. The average flower diameter was approximately 10 cm. A positive correlation was found between the stalk diameter and number of flowers per stalk; the thicker the stalk, the more flowers set.

Morphological and genetic diversity among wild population of Lilium rubellum in Japan

Lilium rubellum Baker is distributed in the north part of Honshu, the main island of Japan. It is belongs to section Archelirion and have been used as important parent species of Oriental hybrid lily cultivars. This species has pink coloured tepals with red coloured spots. However their genetic diversity has not been analysed. We performed morphological and microsatellite (SSR) analysis. We used 145 individual from 12 populations for morphological analysis and 185 individuals from 12 populations for SSR analysis. These results indicated that L. rubellum has genetic differences among populations.

Comparison of Defensive Enzyme Activities in the Leaves of Seven Oriental Lily Hybrids after Inoculation with Botrytis elliptica

Plant resistance characteristics are closely related to changes in the activities of self-defense enzymes after infection. Despite significant differences in the resistance of different lily (Lilium sp.) cultivars to leaf blight (Botrytis elliptica), few studies of their resistance physiology exist. This study explored changes in the resistance-related enzyme activity of several lily cultivars after leaf blight inoculation. Seven oriental lily cultivars (Lilium hybrids) with obvious differences in resistance were used as experimental materials. After inoculation with B. elliptica, the activities of four defense enzymes, superoxide dismutase (SOD), catalase (CAT), phenylalanine ammonia-lyase (PAL), and peroxidase (POD), were determined according to the light absorption values at different wavelengths after their reactions. The results showed that the activities of SOD and CAT differed between the highly resistant and highly susceptible hybrids. Before inoculation, SOD activity was relatively low in all cultivars. However, after inoculation, the SOD activity increased sharply in the resistant cultivars. In the moderately resistant cultivars, the SOD activity did not change drastically. In the susceptible cultivars, the SOD activity initially showed slight increases or decreases and then increased. CAT activity showed reactions similar to those of SOD. Some changes in PAL and POD activity occurred after inoculation, but no significant correlations were present between these trends and resistance characteristics. In addition, no significant changes in enzyme activities were found in the control plants of the seven cultivars during the testing period. Overall, the resistance of Lilium oriental hybrids to B. elliptica is related to SOD and CAT activity but does not show much of a relationship with PAL and POD activity. Studying the physiological metabolic pathways of SOD and CAT appears to be an important direction in research to elucidate resistance to B. elliptica in Lilium oriental hybrids.

Growth Characterization and Cytogenetic Analysis of Three FA Interspecific Hybrid Lilies Bred from Korea

Growth Characterization and Cytogenetic Analysis of Three FA Interspecific Hybrid Lilies Bred from Korea

An R2R3-MYB transcription factor ODORANT1 regulates fragrance biosynthesis in lilies (Lilium spp.)

Flower fragrance is an important character for economic and ecological reasons. Lilies (Lilium spp.), important ornamental crops, mainly emit benzenoids/phenylpropanoids and terpenoids. Oriental hybrid lilies emit a strong fragrance, while Asiatic hybrid lilies often emit a weak fragrance. To delineate the genetic backgrounds that regulate volatile benzenoid/phenylpropanoid production in lilies, we isolated an R2R3-MYB transcription factor similar to Petunia × hybrida ODORANT1 (ODO1) from Oriental and Asiatic hybrid lilies. An identified gene, named Lilium hybrid ODO1 (LhODO1), could upregulate the expression of shikimate pathway genes and phenylalanine ammonia lyase (PAL) genes in transgenic petunia plants. The expression of LhODO1 in the Oriental hybrid lily ‘Casa Blanca’ exhibited a diurnal rhythm, which was highest at 16:00 and lowest at 4:00, and was attuned to the expressional rhythms of shikimate pathway and PAL genes. These diurnal changes in gene expression preceded changes in the production of endogenous volatile compounds. Expression of LhODO1 was specific to tepals, which are major sources of floral scent, and began at anthesis. These results indicate that LhODO1 plays a key role in the regulation of volatile benzenoid/phenylpropanoid production in lilies. In addition, LhODO1 may be responsible for the different fragrance intensities observed between the Oriental and Asiatic hybrid lilies, because LhODO1 expression was high in the Oriental hybrid lily cultivars but very low in wild lilies in sections Sinomartagon and Daurolirion, which are parental species of Asiatic hybrid lilies.

Production of pollenless triploid lily hybrids from Lilium pumilum DC. × ‘Brunello’

Embryo rescue was employed to create four pollenless Asiatic triploid lily hybrids, ‘PB1’, ‘PB2’, ‘PB3’ and ‘PB4’, from the cross of Lilium pumilum DC. (2n = 2x = 24) and the Asiatic lily cultivar ‘Brunello’ (2n = 4x = 48). Cytological observation confirmed that all four hybrids were triploid (2n = 3x = 36) and that the progeny and their parents all shared the 3B karyotype. Some abnormal behavior was observed in the triploid hybrids during pollen mother cell meiosis, including chromosome bridges, lagging chromosomes, micronuclei and unequal separation. The hybrids ‘PB1’ and ‘PB2’ had malformed anthers that were pollenless and could not release pollen grains, but the other two hybrids, ‘PB3’ and ‘PB4’, had a few pollen grains in anthers that were almost normal in shape. The stem diameter, leaf index, inner perianth length, outer perianth length and flower diameter of the four hybrids were all intermediate between the respective traits of the parents. However, plant height, stem diameter and flower number per plant were superior in hybrid plants compared to both parents. Flower color, hairs on bud, flower direction and tepal shape showed wide segregation among the hybrids. Hybrid ‘PB2’ was also fragrant. The four triploid hybrids can be used as garden plants directly or as new genetic resources for breeding pollenless lily cultivars.

Mechanisms suppressing carotenoid accumulation in flowers differ depending on the hybrid groups of lilies (Lilium spp.)

White is among the most important flower color hues in floricultural plants. Accumulation of visible pigments, including carotenoids, is restricted in white flowers. Mechanisms that suppressed carotenoid accumulation were evaluated in lily (Lilium spp.) tepals. Carotenoid content reduced with the development of flower buds in white and pink (caused by anthocyanins) tepals of lilies. As the enzyme carotenoid cleavage dioxygenase 4 (CCD4) degrades carotenoids and is responsible for white flower development in some plant species, the CCD4 gene was isolated in lilies and its expression profiles were investigated: one day before anthesis when tepals became white, CCD4 was expressed in Asiatic and Oriental hybrid lilies, but was expressed only at low levels in L. × formolongi and L. longiflorum (a longiflorum group). Next, carotenoid biosynthesis genes were isolated and their expression was evaluated. Expression of most of the biosynthesis genes was seen in Asiatic hybrid lilies; however, expression of phytoene synthase (PSY) and β-ring hydroxylase (HYB) genes was downregulated in the longiflorum group, and expression of several genes, including PSY and ε-ring hydroxylase, was suppressed in Oriental hybrid lilies. Thus, the mechanisms that suppress carotenoid accumulation might be different among the lily groups: Suppression of PSY and HYB expression was the major mechanism in the longiflorum group lilies, elevated expression of CCD4 was mainly responsible in Asiatic hybrid lilies, and both biosynthesis gene suppression and upregulation of CCD4 were involved in Oriental hybrid lilies.

Compare to ultrastructure of root of resistant and susceptible oriental lily clones by Fusarium oxysporum f. sp. lilii

The production of lily bulbs and flowers is under serious threat from basal rot of the bulbs caused by the soil-borne fungus Fusarium oxysporum f.sp. lilii. Oriental lily hybrid ‘Casa Blanca’ resistant clones to Fusarium oxysporum f.sp. lilii was available by toxin screening. To explore disease-resistance based on the cytology, colonization processes in the resistant oriental lily clones following inoculation with Fusarium oxysporum f.sp. lilii were studied prepared by transmission electron microscopy for ultra section preparation. Samples of susceptible clones and selected resistant clones were collected before inoculation and 3–6 days after inoculation and processed following conventional procedures. Before inoculation, from the ultrastructure of the cells and tissues, more starch grains in selected resistant somaclones and less starch grains in susceptible somaclones. After inoculation, from the ultrastructure of the cells and tissues, selected disease-resistant clone mainly in terms of resistance to extension mechanism is better than susceptible somalclones. Less number of hyphae found in disease-resistant clone cells. Resistant clone cells have a large number of degradable material and secretion, thus preventing fungus extension ability stronger. All of these results showed that Fusarium oxysporum after the invasion of disease-resistant clones is greatly hindered further expansion of the process.