Genomic analysis and marker-assisted selection have long been familiar terms. Nevertheless, compared with that on other horticultural crops, genome-related research on ornamentals has been delayed because of the polyploid nature and/or highly heterozygous genetic background of many such species. With the advent of next-generation sequencing (NGS) technology in recent years, however, the situation is changing. The acquisition of comprehensive transcriptome sequences using NGS technology has been conducted in major ornamentals, and whole-genome sequences have been generated for carnation. This review discusses recent progress in the genomic analysis of carnation, including the construction of an SSR-based reference genetic linkage map, QTL analysis of carnation bacterial wilt (CBW) resistance, and the development of tightly linked markers for CBW resistance and flower type. The current state of NGS technology-based genomic research is also summarized for other major ornamentals.
Pear (Pyrus communis L.) fruit are not usually allowed to ripen on the tree. Indeed, they are harvested at the mature green stage and ripened off the tree. In this study, we examined inhibitory factors that affect the ripening of pear fruit on the tree. The relationship between ethylene and fruit abscission was investigated in ‘Bartlett’ pears. Fruit at the mature green stage produced little ethylene, but most fruit rapidly produced ethylene 2–3 days before dropping. Fruit drop was stimulated by ethylene treatment of fruit on the tree, but was delayed by treatment with 1-methylcyclopropene. We also investigated how fruit ripening on the tree was affected by a continuous supply of assimilates to the fruit via phloem transport. To suppress phloem transport, a girdling treatment was applied to the branch above the abscission zone. Fruit ripening on the tree was promoted by this girdling treatment, but the fruit dropped before softening to an edible firmness. 1-Naphthaleneacetic acid (NAA) was highly effective in suppressing fruit drop. NAA treatment alone did not induce full ripening on the tree, but fruit did ripen on the tree when the NAA and girdling treatments were combined. Two factors may explain why pear fruit do not fully ripen on the tree: the production of ethylene by the fruit during ripening on the tree does not occur until after the optimal harvest time and the continuous supply of assimilates to the fruit via phloem transport may delay ripening.
This study was performed to examine differences in cold hardiness, carbohydrate content, and β-amylase gene expression during cold acclimation and deacclimation in shoots of two peach cultivars (Prunus persica ‘Daewol’ and ‘Kiraranokiwami’). During cold acclimation (from September to November 2011), cold hardiness of the cultivars as determined by electrolyte leakage analysis increased dramatically. Maximum cold hardiness was reached at the end of December 2011 in both cultivars. During deacclimation (late January to April 2012), the cold hardiness of both cultivars decreased gradually. According to the temperatures at which 50% injury occurred (LT50), there was a noticeable difference in cold hardiness between ‘Daewol’ and ‘Kiraranokiwami’ during the deacclimation period from the end of January 2012. Cold hardiness was significantly associated with total soluble sugar, sucrose, and β-amylase gene expression in both cultivars. Sorbitol, the most abundant soluble sugar, was not associated with cold hardiness in either cultivar. Glucose and fructose contents in ‘Daewol’, which was more freezing-tolerant, were approximately double those in ‘Kiraranokiwami’ from January to February 2012. These results suggest that the conversion of sucrose to glucose and fructose might be correlated with the difference of cold hardiness during deacclimation in these peach cultivars.
To obtain basic information about doubled haploid plants in Citrus, in the present study, we investigated the morphological characteristics in doubled haploid induced by colchicine-treated axillary shoot buds of a haploid plant from ‘Banpeiyu’ pummelo [C. maxima (Burm.) Merr.]. We also evaluated the reproductive potential of the doubled haploid as a male or a female parent by crossing with some diploids. In term of the results, this doubled haploid had significantly large leaf, flower and fruit compared with those of the original haploid plant. Moreover, the doubled haploid showed higher pollen fertility (84.1% stainability and 32.9% pollen germination rate) and a larger number of seeds (47.2 developed seeds per open-pollinated fruit) than the haploid. In the reciprocal crosses between the doubled haploid and some diploids, many developed seeds were obtained. These seeds germinated normally and developed into diploid seedlings. These results show that the doubled haploid will be valuable for genetic analysis and possibly for planned breeding.
In order to modify nutrient solution for tomatoes grown in extremely low-volume substrate (ELVS) combined with low-node-order pinching and high-density planting (LN&HD), the effects of nutrient solution concentration and supplemented K and P were investigated. Plant growth, nutrient uptake, and fruit yellow-shoulder disorder were measured in two experiments. Treatments included three nutrient solution concentration levels (0.6, 0.9, and 1.2 dS·m−1 EC) in Experiment 1 and added K or P (EC 0.9+K, EC 0.9+P) and P+K (EC 0.9+P+K) on the basis of Enshi nutrient solution at EC 0.9 dS·m−1 in Experiment 2. Tomatoes ‘CF Momotaro York’ were grown in a 250 mL pot filled with granular rockwool combined with LN&HD. A high-frequency and small-volume fertigation system was used based on the integrated solar radiation amount. In Experiment 1, mineral elemental uptake rate, plant growth and fruit yield increased with increasing nutrient solution concentration, and fruit yellow-shoulder disorder decreased. In Experiment 2, P supplementation treatments of EC 0.9+P and EC 0.9+P+K largely enhanced fruit yield, shoot weight and all nutrient uptake rates. In contrast, yield improvement was not observed at EC 0.9+K, and only K uptake was promoted in K-supplemented treatment. The fruit yellow-shoulder incidence and index tended to decrease in the following order: EC 0.9 > EC 0.9+P > EC 0.9+K > EC 0.9+P+K. In conclusion, it was effective to increase P and K concentrations of nutrient solution on the basis of Enshi nutrient solution formula (EC 0.9 dS·m−1), to maintain optimal tomato vegetative growth, achieve higher yield comparable to that with EC 1.2 dS·m−1, and produce fewer P- and K-deficiency symptoms in the case of ELVS combined with LN&HD culture by a high-frequency and small-volume application method.
The effects of lower nitrogen (N, 4 me·L−1 NO3-N) concentration on growth, fruit yield, and yellow-shoulder (YS) disorder of tomatoes (Solanum lycopersicum L.) were investigated at EC 0.9 dS·m−1 (N, 6 me·L−1 NO3-N) combined with potassium (K) supplementation. Tomatoes ‘CF Momotaro York’ were grown in extremely low-volume substrate (ELVS) combined with low-node-order pinching and high-density planting (LN&HD). An experiment with five nutrient solution treatments of Enshi formula nutrient solution at EC 0.6 and EC 0.9 dS·m−1, EC 0.6+KNO3 (in which 1 me·L−1 KNO3 was added to EC 0.6 dS·m−1), EC 0.6/0.9 (nutrient solution ranging from EC 0.6 to EC 0.9 during fruit enlargement and ripening stages) and EC 0.9+P+K (P and K concentrations increased to 4.6 and 5.8 me·L−1 in EC 0.9) was conducted. Tomatoes were grown in 250 mL pots filled with granular rock wool combined with LN&HD from Feb. 10 to May 29, 2012. The fertigation system of high frequency and small volume was based on integrated solar radiation level. Total yield and YS index at EC 0.6+KNO3 almost reached those at EC 0.9, but they were still significantly lower than those at EC 0.9+P+K. YS index decreased significantly when K concentration increased by 1 me·L−1 (2 to 3 me·L−1). The results suggest the possibility of increasing the yield when a lower-N (5.3 me·L−1) nutrient solution is applied in the ELVS culture system, if P and K concentrations are further modified to enhance the uptake. Shoot fresh weight at EC 0.6/0.9 was significantly lower than at EC 0.9, but there was no significant difference in total yield between EC 0.9 and EC 0.6/0.9. Total yield increased with increasing NO3-N uptake per plant (R2 = 0.98, P < 0.01) and YS incidence of fruit decreased with increasing K uptake per plant (R2 = 0.92, P < 0.05) during the entire growing period.
The genetic factor controlling the mode of plastid DNA (ptDNA) inheritance in Rhododendron was investigated using polymerase chain reaction-single-stranded conformation polymorphism (PCR-SSCP) analysis at the trnL–trnF intergeneric region. In the cross of R. kaempferi var. macrogemma × R. simsii, a low frequency of paternal ptDNA inheritance was observed in the progeny. In the cross of R. transiens × R. simsii, a high frequency of paternal ptDNA was observed in the progeny. When the F1 plants from R. kaempferi var. macrogemma × R. transiens were used as seed parents and were crossed with R. simsii, the pattern of ptDNA inheritance was segregated into 2 types among cross combinations at a ratio of 1:1, namely, low (2.0–11.1%) and high (32.6–66.6%) frequencies of paternal ptDNA inheritance, although the F1 plants had identical ptDNA from R. kaempferi var. macrogemma. From these results, we conclude that the mode of ptDNA inheritance is controlled by at least one major gene in the maternal nucleus.
As the vase life of cut flowers is one of the most commercially important characteristics, genetic improvement of this trait is very desirable. Therefore, we started a breeding research program in 1992 to improve the vase life of flowers in carnation (Dianthus caryophyllus L.) using conventional cross-breeding techniques. We repeatedly crossed and selected promising progeny for three generations, from 2003 to 2010, in order to select lines that exhibit extremely long vase life and low ethylene sensitivity. In 2010, we finally selected a line, 806-46b, with both ultra-long vase life and ethylene resistance out of 50 progeny derived from a cross between 606-65S and 609-63S. The mean vase life of line 806-46b was 27.1 days (444% the value of a control cultivar, ‘White Sim’) at 23°C and 70% RH under a 12-h photoperiod, without chemical treatment, which was the longest vase life among the 6 cultivars and 7 lines tested. Line 806-46b also showed reduced ethylene sensitivity. The response time to 10 μL·L–1 ethylene of this line was 21.8 h, whereas that of ‘White Sim’ was 5.8 h. Line 806-46b did not show brownish discoloration of petal edges during senescence, which was a typical senescence symptom of other selected lines with low ethylene production, when the flower lost its ornamental value. Instead, its petals exhibited gradual reduction of surface turgor by moisture loss as senescence proceeded. This unique senescence pattern is shared by our previously reported line 532-6 with an ultra-long vase life. Line 806-46b showed extremely low ethylene production at senescence, which was also true after ACC treatment. Exogenous ethylene treatment to flowers of this line induced ethylene production without petal wilting, indicating that autocatalytic ethylene production functions normally.
This paper presents an evaluation of the effectiveness of removing air pollutants by installing green vertical walls filled with potted plants. Most people in urban areas spend 80–90% of their lives indoors, indicating the significance of indoor air quality. Carbon dioxide (CO2) and formaldehyde (HCHO) are the most common sources of indoor pollution; their levels can be reduced by using potted plants, which provide the additional benefit of beautification. In accordance with our previous study, for this purpose, we used bird nest fern (Asplenium nidus Linn.), which has a high rate of transpiration and is easy to grow indoors. Upon using 3 treatments involving the release of CO2, HCHO, or CO2 + HCHO, the experimental results showed that bird nest fern can reduce the concentration of CO2 from 2000 ppm to a safe 800 ppm at an average of 1.984 ppm·h−1 (per pot). By contrast, the concentration of HCHO was reduced from 2 ppm to the safe level of 0.1 ppm, at an average of 0.003 ppm·h−1 (per pot). Regarding temperature and humidity, the results showed a decrease of 2°C indoors and an increase of 10% relative humidity. These results show that bird nest fern has high rates of CO2 and HCHO removal, reduces temperature, and raises relative humidity.
A new acetylated anthocyanin was extracted from the red-purple flowers of Saintpaulia ‘Tomoko’ with 5% HOAc-H2O or 5% formic acid-H2O, and determined to be peonidin 3-O-[6-O-(4-O-(acetyl)-α-rhamnopyranosyl)-β-glucospyranoside] (1), by chemical and spectroscopic methods. In addition, two known acetylated cyanidin glycosides, cyanidin 3-O-[6-O-(4-O-(acetyl)-α-rhamnopyranosyl)-β-glucospyranoside] (2) and cyanidin 3-O-[2-O-(β-xylopyranosyl)-6-O-(acetyl)-β-glucopyranoside] (3), were also identified in the red-purple flowers and grayed-purple leaves of S. ‘Tomoko’, respectively. These three anthocyanins have not been reported hitherto in plant tissues in the genus Saintpaulia.
Understanding the control of anthocyanin biosynthesis is beneficial to genetic improvement for floral production in Dendrobium orchids. Full-length cDNA of CHS, CHI1, CHI2, F3H, DFR, ANS, F3'5'H, and FLS was isolated from Dendrobium hybrids with purple, peach, white and greenish white flowers. Analysis of the deduced amino acid sequences and gene expression levels of the eight genes suggested potential causes of color variation among the hybrids. Peach hybrid (SC) was likely due to changes in anthocyanin production from cyanidin to pelargonidin through mutations in F3'H, and the low color intensity was likely derived from the low expression levels of CHI1 and CHI2. In addition, white hybrid (RW) was likely caused by several mutations in F3H and/or high expression levels of FLS, an enzyme that converts color flavonoid intermediates into colorless flavonols. Simultaneous loss of F3H, DFR, and ANS expression observed in another white hybrid (JW) indicated that an alteration of anthocyanin regulatory controls was likely the cause of white coloration. Furthermore, analysis of hybrid mutants bearing pale and dark flowers demonstrated the influence of the expression of anthocyanin genes on the intensity of flower colors. Data obtained from this work could contribute to new strategies for future orchid breeding.