Wen-Shaw Chen

Studies on somaclonal variation in Phalaenopsis

Abstract The morphological and genetic variations in somaclones of Phalaenopsis True Lady “B79-19” derived from tissue culture were evaluated. In 1360 flowering somaclones, no apparent difference was found in the shape of the leaves, whereas flowers in some somaclones were deformed. We have demonstrated that 38 selected random primers can be used to generate amplified segments of genomic DNA and to differentiate polymorphisms of somaclonal variations in Phalaenopsis. The random amplified polymorphic DNA (RAPD) data indicated that normal and variant somaclones are not genetically identical. We also studied the banding patterns of aspartate aminotransferase (AAT) and phosphoglucomutase (PGM) in young leaves of variant and normal somaclones of Phalaenopsis. With respect to AAT, three distinct banding patterns were found in normal somaclones and only two-banded phenotypes were detected in variant somaclones. In a comparison of the banding patterns of PGM isozymes, three to four bands were detected in normal somaclones and two to three bands in variant ones.

Postharvest life of cut rose flowers as affected by silver thiosulfate and sucrose.

A pulse treatment of sucrose at 0, 20, 40, 60, 80, 100, and 120gL(superscript (-1)) in combination with 8-hydrox-yquinoline sulfate (HQS) at 200 mg L(superscript (-1)) for 10h was evaluated daily for its effect on the vase life and flower quality of cut rose flowers. The pulse treatment of sucrose at above 80gL(superscript (-1)) produced a vase life of 6 to 7 days, while at below 80gL(superscript (-1)) vase life was maintained for 4 days on average. The pulse treatment of silver thiosulfate (STS) at 0.2mM for 2h or STS for 2h followed by sucrose at 120gL(superscript (-1)) supplemented with HQS for 10h extended the vase life of cut rose flowers to about 9 and 10 days, individually. On the other hand, a pulse treatment with sucrose or distilled water in combination with HQS maintained vase life for 7 and 3 days, respectively. Flower quality of specimens treated with STS followed by sucrose in combination with HQS was better than that of those treated with STS alone. Although visual quality could be maintained for up to 13 days in STS followed by sucrose in combination with HQS, flower quality decreased notably after 10 days. The ethylene production was greatest in untreated rose flowers (about 3h after harvest) and decreased after chemical solutions treatment. The inhibition of ethylene production was greater in sucrose in combination with HQS than with STS or STS followed by sucrose along with HQS, although the effectiveness of the latter for maintaining rose vase life was better than the former.

Changes in Cytokinin levels of Phalaenopsis leaves at high temperature

The effect of high temperatures on cytokinin levels in Phalaenopsis hybrida leaves was investigated. Endogenous cytokinins were identified and quantified in Phalaenopsis leaves grown under high temperature conditions (30/25 °C day/night) using high performance liquid chromatography, bioassay and gas chromatography-selected ion monitoring-mass spectrometry. After 5 and 20 d of low temperature (25/20 °C day/night), zeatin, zeatin riboside and dihydrozeatin levels in the leaves were higher than that in leaves subjected to high temperature treatments. When Phalaenopsis leaves were exposed to low temperatures, about 76 % of the free cytokinins detected were of the zeatin-type. Glucoside cytokinins in the leaves increased significantly 5 d following high temperatures, and the rate of increase in glucoside cytokinins corresponded to the duration of high temperatures. At the same time, zeatin riboside and dihydrozeatin declined significantly following high temperature application. A significant accumulation of glucoside cytokinins, zeatin-9-glucoside, zeatin-O-glucoside, zeatin riboside-O-glucoside, and dihydrozeatin-O-glucoside was observed 20 d following high temperatures. These results suggest that high temperatures lead to an accumulation of glucoside cytokinins and a reduction of free base and riboside cytokinins.

Changes in cytokinin activities before, during and after floral initiation in Polianthes tuberosa

Abstract The contents of endogenous cytokinin in tuberose corms (Polianthes tuberosa) at vegetative, early floral initiation, and flower development stages were investigated. We also determined the influence of exogenous cytokinin treatment on the corm apex at three different growth stages in relation to floral initiation and development in tuberose. The exogenous cytokinin effectively induced floral initiation and development, especially at the early floral initiation and flower development stages. Endogenous cytokinins were higher in early floral initiation and development stages in comparison to the vegetative stage. During floral initiation stage, the zeatin and dihydrozeatin increased significantly, while the cytokinins, zeatin riboside, dihydrozeatin riboside, 6N-(δ2-isopentenyl) adenine, and 6N-(δ2-isopentenyl) adenine riboside at consistently low levels. The increase of cytokinin levels in tuberose corms during floral induction suggests a role for cytokinins in tuberose apex evocation. Moreover, these results indicate that cytokinins seem to promote the development of flower buds rather than inducing flowering in tuberose.

Abscisic acid affects floral initiation in Polianthes tuberosa

Summary Application of 5 or 25 μg abscisic acid (ABA) per plant to the upper part of corms of Polianthes tuberosa L. (cv. Double) at the vegetative stage inhibited floral initiation and plant height, especially when ABA at 25 μg per plant was applied. The contents of endogenous free ABA in corms decreased significantly at the floral initiation stage, and remained at a low level at flower development stage as compared with the vegetative stage. However, no significant changes in bound ABA levels were observed at three different growth stages of corm development. These results suggest that the dramatic reduction in the free ABA content in corm tissues are correlated with floral initiation and flower development in P. tuberosa.

Vase life of Eustoma grandiflorum as affected by aluminum sulfate

A floral preservative solution containing aluminum sulfate at 150 mg L^(-1) under 25℃, extended cut eustoma (Eustoma grandiflorum Shinn. cv. Hei Hou) vase life. The vase life was about 15 days for cut flowers supplied with aluminum sulfate, whereas the vase life of the water controls was only 8 days. The fresh weight of cut eustoma flowers treated with aluminum sulfate continued to increase up to 8 days after vase treatment, then declined thereafter. By contrast, the fresh weights of cut eustoma flowers in water controls began to reduce at the 6th day after vase treatment. The water loss from cut eustoma flowers treated with aluminum sulfate was lower than that of water controls during vase period, and the reverse was true for water uptake.

Changes in free and conjugated indole-3-acetic acid during early stage of flower bud differentiation in Polianthes tuberosa

Tuberose (Polianthes tuberosa L. cv. Double) corms at the vegetative, early floral initiation, and flower bud differentiation stages were assayed for free indole-3-acetic acid (IAA), esterified IAA, and peptidyl IAA. The corms in the vegetative stage contained higher free IAA than those from the early floral initiation stage. Free IAA in corm tissues increased 2.7-fold at flower bud differentiation as compared to the vegetative stage. In the vegetative corms, a marked promotion of leaf differentiation was recorded. In contrast, corms from the early floral initiation stage contained less free IAA, whereas esterified IAA and peptidyl IAA increased dramatically. It is concluded that the level of free IAA in vegetative corms is correlated with leaf differentiation, and that the early floral initiation stage is correlated with a reduction in free IAA and an increase in IAA conjugates in the corms. Moreover, increases in free IAA and decreases in IAA conjugates in the floral differentiation stage, as compared to the early floral initiation stage, indicates that free IAA is correlated with flower development.

Improvement of postharvest vase life and flower bud opening in Polianthes tuberosa using gibberellic acid and sucrose

Pulsing with gibberellic acid followed by continuous sucrose treatment enhanced flower longevity and flower bud opening in cut Polianthes tuberosa L. cv. Double. Pulsing with gibberellic acid at 10 or 20 mg/L plus 8-hydroxyquinoline sulfate (200 mg/L) for 24 h followed by continuous sucrose treatments (4 or 8%) plus 8-hydroxyquinoline sulfate extended the vase life and significantly promoted flower bud opening as compared with the 8-hydroxyquinoline sulfate controls. A pulse with a higher concentration of gibberellic acid (50 mg/L) followed by sucrose solutions did not increase vase life or enhance flower bud opening greater than those pulsed with gibberellic acid at 10 or 20 mg/L followed by 8-hydroxyquinoline sulfate. A gibberellic acid (10, 20 or 50 mg/L) pulse followed by 8-hydroxyquinoline sulfate holding solution had little effect on longevity and flower bud opening in comparison to 8-hydroxyquinoline sulfate controls. Similarly, continuous sucrose treatment at 4 or 8% without a gibberellic acid-pulsed treatment also showed little effect on vase life and flower bud opening. Cut P. tuberosa treated with a gibberellic acid pulse followed by 8-hydroxyquinoline sulfate produced more ethylene than those treated with 8-hydroxyquinoline sulfate alone. Ethylene production from flowers pulsed with gibberellic acid followed by sucrose was low when compared with controls or those pulsed with gibberellic acid alone. Cut stems continuously placed in solutions containing sucrose produced less ethylene than those without sucrose. It is suggested that a gibberellic acid pulse at 10 mg/L followed by continuous sucrose treatment at 4% be recommended to growers for extending the vase life and enhancing flower bud opening in cut P. tuberosa.

The synergistic effect of maleic acid hydrazide (1.2-dihydro-3,6-pyridazinedione) and sucrose on vase life of cut roses

Continuous postharvest treatment of cut rose flowers (Rosa hybrida L. cv. Diana) with maleic acid hydrazide (1.2-dihydro-3,6-pyridazinedione, MH) at 560.5 8-hydroxyquinoline sulfate (HQS) at 388.4 HQS, MH + HQS or sucrose + HQS treatments. The longevity of flowers in MH + sucrose in combination with HQS was extended for 18 days after vase treatments, whereas the longevity of cut flowers was only 4, 6 and 8 days for HQS, MH + HQS and sucrose + HQS, respectively. Cut roses treated with MH + sucrose + HQS in vase solution exhibited greater water uptake and less water loss than those in HQS. The concentrations of various sugars in petals were highest in the sucrose + HQS treatment, and MH + sucrose + HQS > MH + HQS > HQS. Ethylene production was significantly lower in sucrose + HQS or MH + sucrose + HQS treatments in comparison to MH + HQS, or HQS.