The changes in cytokinins and gibberellins in xylem sap of lychee (Litchi chinensis Sonn. cv. Heh yeh) trees were investigated at the stages of leaf expansion, dormant bud (when apical leaves are dropped), 30 days before flower bud formation, flower bud formation, and full bloom of grafted field-grown lychee trees. Also; the diffusible IAA and ABA in diffusate from shoot tips were examined at the successive stages of development. High gibberellin was found in the xylem sap at the stage of leaf expansion. A constant level of IAA was maintained through the five growth stages. At 30 days before flower bud formation, ABA increased dramatically. Concurrently, total cytokinin content increased in the xylem sap, reaching a maximum during flower bud formation and full bloom. Gibberellin content in the xylem sap was at a low level 30 days before flower bud formation and through the stage of flower bud formation.
Wen-Shaw Chen, Hsueh-Wen Chang, Wen-Huei Chen and Yih-Shyan Lin
Gibberellin A3 (GA3: 1, 3, or 5 (μg/shoot), 6N-benzyladenine (BA: 1, 3, or 5 μg/shoot), or both were applied to the flowering shoots of a white hybrid Phalaenopsis orchid (Leda) when they were 2 to 3 cm (stage 1, no flower primordial long at high temperature (30 °C day/25 °C night). When flowering shoots were treated with GA3, alone, deformed flowers were more frequent with increasing GA3 concentrations. The occurrence of GA3-induced deformed flowers was prevented by BA at the same dose as GA3 when applied 4 days after GA3 treatment. BA (1, 3, or 5 μg/shoot) was also applied 4 days before (time 1) or 4 days after (time 2) GA3 (1 (μg/shoot) treatment for regulating plant characteristics. The application of BA at 1 or 5 μg/shoot to stage 1 flowering shoots at time 2 resulted in short internodes between florets, whereas BA application at time 1 had no effect. Simultaneously, BA at 1 or 5 μg/shoot applied at time 1 or time 2 to stage 2 (5 to 6 cm long, two- to three-flower primordia) flowering shoots also shortened internode length between florets as compared to GA3 alone. When a stage 1 flowering shoot was given BA (3 or 5, but not 1 μg/shoot) and then treated with GA3 4 days later, flower count was slightly reduced as compared to treating with (GA3 alone. However, a high dose of BA applied at time 1 or time 2 on stage 2 flowering shoots had no effect on flower count. Chemical names used: N-(phenylmethyl)-lH-purine-6-amine [benzyladenine (BA)], gibberellic acid (GA3).
Kuang-Liang Huang and Wen-Shaw Chen
An experiment was conducted to measure the effects of pulse treatments of BA, sucrose, and BA before, after, or with sucrose, on the vase life of cut Eustoma flowers. A BA pulse at 50 mg·L-1 before 4% sucrose promoted the longevity of cut Eustoma flowers better than other treatments. Simultaneously, sucrose, glucose, and mannose concentrations in flowers during vase periods were maintained at higher levels in double pulse treatments than in the single pulses. Ethylene production in flowers 2 days after vase treatment was highest in the BA-treated flowers; intermediate in flowers pulsed with BA before, after, or with sucrose; and lowest in sucrose-treated flowers. Although a BA pulse increased ethylene production over that of controls, it inhibited senescence in cut Eustoma flowers. Respiration in flowers pulse-treated with sucrose or with BA before, after, or with sucrose, was significantly higher than that in controls. Results suggest that the vase life of cut Eustoma flowers is improved by either BA or sucrose in vase solution and especially when BA was pulsed before the sucrose pulse. Chemical name used: N6-benzyladenine (BA).
Huai-Fu Fan, Wen Chen, Zhou Yu and Chang-Xia Du
Salt stress reduces the fresh weight, dry weight, and relative growth rate of cucumber (Cucumis sativus) seedlings and results in serious quality loss in cucumber production. Our previous study indicated that the netting-associated peroxidase (CsaNAPOD) protein in cucumber seedling roots was induced by salt stress. Here, we amplified the coding sequence of CsaNAPOD from a cDNA isolated from the roots of cucumber seedlings. Sequence analysis indicated that the coding sequence of CsaNAPOD is 1035 bp, encoding a deduced protein of 344 amino acids, with a predicated molecular weight of 37.2 kD and theoretical isoelectric point of 5.64. The deduced amino acid sequence of CsaNAPOD showed high sequence similarity to peroxidases (PODs) from other plant species. Moreover, CsaNAPOD possesses the typical sequence structures of class III PODs and indicated that CsaNAPOD belongs to this subfamily. CsaNAPOD was highly expressed in the roots and was weakly expressed in the stems and leaves of cucumber seedlings. Salt stress significantly increased the expression of CsaNAPOD in the leaves during the entire experimental period compared with the control, and the expression of CsaNAPOD in roots was reduced at 6 hours and induced at 48 and 72 hours by salt treatment. In stems, the expression of CsaNAPOD declined at 48 and 72 hours as a result of the salt treatment compared with the control. These results indicate that the expression of CsaNAPOD responded to salt stress in cucumber seedlings, and the expression patterns under salt stress in different tissues were not identical. Our research suggests that CsaNAPOD may have potential function during the plant response to salt stress.
Pablo Bolaños-Villegas, Shih-Wen Chin and Fure-Chyi Chen
The development of new cultivars in Doritaenopsis Guillaum. & Lami orchids is often hindered by factors such as low seed count in hybrids. Cytological study may offer the ability to develop new hybrids by revealing cultivars with good chromosome pairing and high pollen viability, which are somewhat difficult to obtain under current breeding programs. Cross pollination, pollen viability, and chromosomal behavior during meiosis were analyzed to reveal the relation between seed fertility and capsule set in Doritaenopsis hybrids. The number of mature capsules harvested and their relative seed content were used as indices of crossing availability. The results of meiosis were evaluated according to pollen viability detected by fluorescein diacetate and quantification of sporad types by acid fuchsin staining. Chromosome number and pairing at meiosis were observed in root tips or in samples of pollen mother cells. A positive relation was found among high seed set, high frequency of viable tetrads, high degree of chromosome pairing, and low frequency of chromosomal aberrations such as inversions and translocations. On the basis of these factors, three types of hybrids could be distinguished. In type one hybrids, chromosomes paired as bivalents, pollen mother cells divided into tetrads, and capsule setting occurred after pollination of pollen acceptors. In type two hybrids, chromosomes remained mainly as univalents that developed into micromeiocytes, pollen mother cell division was disrupted, and seed recovery was low after pollination. Type three hybrids showed chromosomes paired mostly as multivalents, chromosome bridges, pollen mother cell division with massive failure, and little fertility. In Doritaenopsis orchids, high pollen viability and high fertility depends on a high frequency of normal tetrads, and low seed set in cross-pollination is predicted with micronuclei in the end products of meiosis. The occurrence of chromosomal aberrations may suggest a process of genome differentiation that could compromise breeding efforts if not taken into consideration.
Yi-Lun Liao, Wen-Shin Lin and Shu-Yun Chen
Hongmei Xia, Wenbin Zhen, Dongyang Chen and Wen Zeng
Taking out and opening the ordinary multilayer fruit paper bag for fruit bagging is labor intensive, costly, not efficient, and potentially dangerous to the operator’s health. There is a high demand to develop a mechanical device for the operation in Chinese orchards. A novel supplying device based on the manual operated fruit bag case was proposed. The open hand of the supplying device operates like a farmer’s hand that can continuously take out a multilayer fruit paper bag one by one, and open it fully from its inside. Mechanism configuration and dimension parameter of the open hand were designed based on preliminary tests. The operation functionality of the supplying device prototype at different driving trajectories and speed was investigated in the study. The laboratory experimental data indicated that driving trajectory was an extremely significant factor for efficiently taking out and opening the fruit bag without sliding off and damage. Driving speed had a beneficial effect on reducing supplying time. With the synchronous driving trajectory and allowable high moving speed, the developed supplying device could achieve more than 90% opening success rate and less than 2-second opening time. The study showed the potential of the developed mechanical supplying device for fruit bagging with ordinary multilayer fruit paper bags.
Yau-Wen Yang, Pai-Yean Tai and Ying Chen
There are two evolutionary pathways in the genus of Brassica, one is rapa/oleracea lineage and the other is nigra lineage. Based on the morphological characteristics and nuclear RAPD or RFLP markers, genus Raphanus was thought more closely related to nigra lineage than to rapa/oleracea lineage (Song et al., 1990; Thormann et al., 1994). RFLP data of both chloroplast and mitochondria revealed that Raphanus is more closely related to rapa/oleracea lineage (Palmer and Herbon, 1988; Warwick and Black, 1991; Pradhan et al., 1992). We have previously demonstrated that Raphanus sativus is more closely related to nigra lineage using nuclear intergenic spacer between 5S rDNA and internal transcribed spacer region between 18S and 25S rDNA. In this study, we analyzed DNA sequences from different regions of chloroplast and showed that Raphanus sativus was closely related to rapa/oleracea lineage than to nigra lineage. These results suggest that Raphanus sativus is a hybrid between B. rapa/oleracea and B nigra lineages as proposed by Song et al (1990). The split time between these two lineages and the divergent time of Raphanus was also determined based on these chloroplast DNA sequences.
Fure-Chyi Chen, Wan-Ling Wu, Chun-Hua Pan, Irwin Yau-Yuan Chu and Yau-Wen Yang
Molecular markers by random amplified polymorphic DNAs were used to evaluate the genetic variation among different Oncidium accessions. It is possible to distinguish different registered Oncidium hybrids, including Gower Ramsey, Sweet Sugar, and Taka using nine random primers. Furthermore, variation was also detected within different cultivars derived from same hybrids. For example, several cultivars of Gower Ramsey could be distinguished based on molecular markers. Based on dendrogram, the investigated cultivars were clustered into several groups. Onc. Gower Ramsey and its selected cultivars were in one group. Onc. Sweet Sugar, Onc. Taka and Onc. Sharry Baby `Sweet Fragrance' were clustered in separate groups.