Ki Sun Kim

De Novo Transcriptome Analysis to Identify Anthocyanin Biosynthesis Genes Responsible for Tissue-Specific Pigmentation in Zoysiagrass (Zoysia japonica Steud.).

Zoysiagrass (Zoysia japonica Steud.) is commonly found in temperate climate regions and widely used for lawns, in part, owing to its uniform green color. However, some zoysiagrass cultivars accumulate red to purple pigments in their spike and stolon tissues, thereby decreasing the aesthetic value. Here we analyzed the anthocyanin contents of two zoysiagrass cultivars ‘Anyang-jungji’ (AJ) and ‘Greenzoa’ (GZ) that produce spikes and stolons with purple and green colors, respectively, and revealed that cyanidin and petunidin were primarily accumulated in the pigmented tissues. In parallel, we performed a de novo transcriptome assembly and identified differentially expressed genes between the two cultivars. We found that two anthocyanin biosynthesis genes encoding anthocyanidin synthase (ANS) and dihydroflavonol 4-reductase (DFR) were preferentially upregulated in the purple AJ spike upon pigmentation. Both ANS and DFR genes were also highly expressed in other zoysiagrass cultivars with purple spikes and stolons, but their expression levels were significantly low in the cultivars with green tissues. We observed that recombinant ZjDFR1 and ZjANS1 proteins successfully catalyze the conversions of dihydroflavonols into leucoanthocyanidins and leucoanthocyanidins into anthocyanidins, respectively. These findings strongly suggest that upregulation of ANS and DFR is responsible for tissue-specific anthocyanin biosynthesis and differential pigmentation in zoysiagrass. The present study also demonstrates the feasibility of a de novo transcriptome analysis to identify the key genes associated with specific traits, even in the absence of reference genome information.

Influence of photoperiod on growth and flowering of dwarf purple loosestrife

This study was conducted to compare the growth and flowering characters of a dwarf purple loosestrife and purple loosestrife (Lythrum salicaria L.), and to determine the optimal photoperiod of dwarf purple loosestrife for forcing cultivation. Dwarf purple loosestrife was grown under natural sunlight (from 08:30 to18:30 HR, 10 h) and additional artificial lighting [0, 2, 3, 4, 6, or 14 h of continual light, or night interruption of 4 h (NI)] in a greenhouse. Growth and development of dwarf purple loosestrife were promoted by 14, 16, or 24 h or NI. The number of lateral shoots and plant height were higher as daylength was extended. However, the number of nodes was not influenced by photoperiod. The number of inflorescences was 0.6, 2.9, 5.0, or 4.2 under 14, 16, or 24 h, or NI, respectively. Also, plants under NI showed more uniform flowering (86%) than those under 14 h (48%). However, plants under 10, 12, or 13 h never produced inflorescences and remained as rosettes throughout the experiment. Therefore, we concluded that dwarf purple loosestrife has a critical photoperiod, 14-h daylength and NI is the effective method to accelerate growth and flowering for forcing cultivation.

Flowering of cyclamen is accelerated by an increase in temperature, photoperiod, and daily light integral

Summary Cyclamen (Cyclamen persicum Mill.) crop production times can be reduced by increasing the greenhouse temperature, but alternative methods to accelerate crop development are desirable when energy costs for heating are high. The effects of photoperiod and increasing daily light integral (DLI) on cyclamen remain unclear. We performed experiments to examine the effect of DLI using two temperatures (16°C or 20°C) and three photoperiods (8, 12, or 16 h) delivering DLI values of 4.9, 7.3, or 9.8 mol m–2 d–1, respectively, and the effect of night interruption (NI) lighting from incandescent lamps (IL), on the flowering of cyclamen ‘Metis Purple Flame’. Plants grown at 20°C reached the visible flower bud (VB) stage earlier than plants grown at 16°C under all photoperiods. NI hastened flower bud initiation by 22 – 29 d compared with an 8-h photoperiod at both temperatures. Plants grown under the 8-h photoperiod with an NI treatment (DLI = 4.9 mol m–2 d–1) flowered at a similar time as plants grown under the 12-h photoperiod (DLI = 7.3 mol m–2 d–1). In addition, plants grown at 16°C with an NI reached the VB stage in a similar time to plants grown at 20°C with an 8-h photoperiod. Therefore, the effects of increasing the DLI, providing NI lighting, or increasing the temperature can be compared, so that growers can determine which strategies can reduce the greenhouse production time of cyclamen most cost-effectively.

Chilling requirement for breaking dormancy and flowering in Paeonia lactiflora ‘Taebaek’ and ‘Mulsurae’

Dormant rootstocks of Paeonia lactiflora ‘Taebaek’ and ‘Mulsurae’ (native Korean cultivars) were stored at three chilling temperatures (constant 0, 5, or 10°C) for different durations (0, 3, 6, 9, or 12 weeks) to determine the chilling requirements for dormancy breaking and flowering. For both cultivars, percent sprouting, numbers of shoots and flowers, and height during flowering increased as the plants were exposed to lower chilling temperatures or longer chilling durations, whereas the time required for sprouting gradually decreased as the duration of the chilling treatment increased. However, there were no significant differences in these parameters between the two cultivars when they were chilled for 9 weeks or more. A chilling treatment at 0°C for 6 weeks [1,008 hours chill unit (CU)] produced more number of shoots and flowers and required fewer days to achieve sprouting and flowering than at 5°C for 6 weeks (706 hours CU). Temperatures of 5°C and 10°C afforded only 70% and 40%, respectively, when compared to a cumulative chill unit at 0°C. ‘Taebaek’ required more chilling to sprout consistently and achieve its potential shoot numbers than ‘Mulsurae’. Chilling for 6 weeks at 0 and 9 weeks at 5°C (1,058 hours CU) were necessary to break dormancy and to induce flowering in P. lactiflora ‘Taebaek’ and ‘Mulsurae’, respectively.

Dormancy Release and Flowering of Paeonia lactiflora 'Taebaek' by Natural Cumulative Chilling and GA3 Treatment

Dormancy breaking and flowering of Paeonia lactiflora ‘Taebaek’ were controlled by natural cumulative chilling and GA3 treatments according to the transfer date in the central region of Suwon, Korea. Shoot emergence and flowering did not occur throughout the experimental period when dormant rootstocks were transferred to a glasshouse between September 10 and October 29, in which the natural cumulative chill (NCU) unit was nearly 0 h. The number of days from the transfer date to sprouting and flowering was shortened as the transfer date was delayed. All the plants flowered normally with shoot growth when they were transferred after December 31 (1,222 h NCU). All dormant buds that were treated with GA3 sprouted, regardless of transfer date, but failed to flower due to shoot blasting and flower bud abortion when they were transferred between September 10 (0 h NCU) and November 12 (185 h NCU). Shoot blasting was 38% when they were transferred on November 26 (429 h NCU). When GA3 was applied to the plants after December 17 (876 h NCU), they flowered without blasting. Plant height and stem diameter were not affected by GA3 treatment. GA3 treatment decreased the number of days to sprouting and flowering, and increased the number of flowers, irrespective of insufficient chilling accumulation, as compared to 1,222 h NCU on December 31. According to the above results, at least 1,222 h NCU could be recommended as a practical forcing method for dormancy release, subsequent growth, and normal flowering of dormant P. lactiflora ‘Taebaek’ in a temperate climate region. The GA3 treatment played an important role in breaking dormancy and significantly increased the percentage of sprouting, accelerated the days to sprouting and promoted the flowering of P. lactiflora ‘Taebaek’ when the plants had undergone insufficient chilling accumulation.

Vegetative growth and flowering of Dianthus, Zinnia, and Pelargonium as affected by night interruption at different timings

Influences of night interruption (NI) application timings were examined on vegetative growth and flowering of Dianthus chinensis (quantitative long-day plant), Zinnia elegans (quantitative short-day plant), and Pelargonium zonale (day-neutral plant). The experiments were conducted both in a greenhouse and in a growth chamber. In both experiments, plants were grown under 9 hours photoperiod [short-day (SD) condition] or 9 hours photoperiod plus 4 hours NI with low light intensity at a photosynthetic photon flux (PPF) of 3–5 μmol m−2 s−1. The NI was employed at 18:00–22:00 HR (NI18), 22:00–02:00 HR (NI22), or 02:00–06:00 HR (NI02). Net photosynthesis of Dianthus during the NI period was determined in the growth chamber experiment. In Dianthus, node number increased more rapidly in all NI treatments regardless of the timing of NI. The height of Zinnia was shorter under NI than under SD, and those grown under NI02 were shorter than those under NI18 or NI22. In Pelargonium, leaves of the plants grown under NI02 were produced more slowly than those of the plants under NI18 and NI22. For these three species, dry weights of the plants under NI were not significantly different from those of the plants under SD. The NI had no effect on net photosynthesis of Dianthus. Flowering of Dianthus was hastened by all NI treatments, more in NI02 than in NI18 or NI22. Zinnia flowered later under NI02 than under NI22 or NI18. Flowering of Pelargonium was not affected by the NI application timing. These results indicate that NI02 was most effective in promoting flowering in Dianthus or inhibiting flowering in Zinnia. However, the NI with low light intensity at 3–5 μmol m−2 s −1 PPF had no significant effect on net photosynthesis and subsequent dry matter accumulation in these three herbaceous plants.

Chilling requirement for dormancy release of variegated Solomon’s seal

Dormancy release of variegated Solomon’s seal (Polygonatum odoratum Druce var. pluriflorum Ohwi for. variegatum Y.N.Lee) was studied by varying the transferring date from the field to greenhouse and by cold storage in order to identify their precise chilling requirement. Bud emergence and flowering did not occur throughout the experiment when dormant rhizomes were transferred until a calendar date November 22, 2009, in which natural cumulative chill unit (NCU) was 75 h. Days to sprouting, flowering, and flower abscission were shortened with delayed transferring dates. Percent sprouting and flowering showed an increasing tendency since rhizomes were transferred on December 7 (= 241 h NCU), but emergence date was not uniform. However, uniform percent sprouting was maintained since rhizomes were transferred on December 22 (= 492 h NCU). No or 1 week of cold storage at 0 or 5°C did not induce sprouting, which meant bud dormancy was not released when rhizomes were stored ≤ 1 week. When they were stored for more 2 weeks at 0 or 5°C, percent sprouting was increased to ≥ 91% in the heated greenhouse. Cumulative chill unit (CCU) was 336 h at 0°C and 225 h at 5°C. However, bud emergence date after 2 weeks of cold storage was not uniform at both storage temperatures, whereas bud emergence after 4 weeks of cold storage at 0°C was more uniform than that at 5°C. Therefore, at least 492 h NCU, 4 weeks of cold storage at 0°C (= 672 h CCU), or 6 weeks at 5°C (= 675 h CCU) is recommended for forcing and normal growth afterward of variegated Solomon’s seal.

Effects of irrigation frequency on root formation and shoot growth of spray chrysanthemum cuttings in small jute plugs

Abstract Small plugs of organic, fibrous material (jute) were used as a propagation medium for spray chrysanthemum cuttings instead of the more conventional, pre-fertilized compressed peat blocks. A complete nutrient solution was supplied to the jute plugs by means of ebb-and-flow irrigation. Four different irrigation frequencies (IF) were compared, i.e. 96, 24, 6 and 1 day−1. During the root initiation stage, the irrigation treatments had little effect on the cuttings. Once a new root system had been generated, a strong positive correlation between IF and growth was observed. Shoots of rapidly growing cuttings contained relatively high levels of nutrients and low non-structural carbohydrate levels and had a high turgor. These results demonstrate that during propagation from cuttings, growth may be limited by the availability of water and minerals. In the case of chrysanthemum cuttings in small jute plugs, factors limiting growth can be overcome by frequent irrigation with a complete nutrient solution.

Non-deep simple morphophysiological dormancy in seeds of Thalictrum rochebrunianum, an endemic perennial herb in the Korean Peninsula

The aims of this study were to determine the requirements for dormancy break and germination and to characterize the type of seed dormancy of T. rochebrunianum. Ripe seeds (achenes) were collected in late Sept. To determine the temperature requirements for embryo growth and germination in the field, the seeds were sown in field soil. Every 1 or 2 weeks, the seeds were exhumed, and the phenology of embryo growth, germination and seedling emergence were investigated. In the laboratory, effects of temperature and GA3 treatment on embryo growth and germination were also investigated to characterize the type of seed dormancy. Seeds had underdeveloped embryos, which were about 20% of the size of those in fully matured seeds. In natural conditions, embryo growth and germination occurred in early and late March next year, respectively, and embryos in the seeds of this species had to grow to a critical length before germination was possible. Thus, the seeds had morphological dormancy (MD). When tested at the time of dispersal, few seeds germinated after 4 weeks of incubation at 25/15°C. Therefore, the seed dormancy type for T. rochebrunianum seemed to be morphophysiological. Embryos in the seeds grew rapidly at warm temperature conditions following cold stratification at low temperatures. After 4–12 weeks of cold stratification at 1°C or 5°C, the seeds germinated rapidly during an incubation at 25/15°C. Cold stratification requirements could be substituted by GA3 treatment in seeds of T. rochebrunianum. After 1000 mg·L-1 GA3 treatment, high percentages (≥ 80%) of the seeds germinated after 4 weeks of incubation at 15/6, 20/10, and 25/15°C. Consequently, seeds of T. rochebrunianum could be characterized as expressing non-deep simple morphophysiological dormancy (MPD). The cold stratification requirements for dormancy break enabled the seeds to produce seedlings at the beginning of the growing season in natural conditions.

Anti-inflammatory effects of flavonoids in Korean Chrysanthemum species via suppression of inducible nitric oxide synthase and cyclooxygenase-2 in LPS-induced RAW 264.7 macrophages

This study was conducted to compare flavonoids and anti-inflammatory effects in Korean Chrysanthemum species. Leaf samples were identified using HPLC/MS with five flavonoids: luteolin-7-O-rutinoside, luteolin-7-O glucoside, apigenin-7-O-glucoside, apigenin, and acacetin-7-O-rutinoside. Leaf extracts from four taxa dose-dependently suppressed LPS-stimulated NO production significantly (p<0.05) inhibited production of LPS-induced PGE2 compared with controls. The extracts reduced the LPS-induced expressions of inducible NO synthase and cyclooxygenase-2 and inhibited LPS-induced tumor necrosis factor-α and interleukin-6 production for anti-inflammatory effects.