Yoshinori Nakao

Changes in indole-3-acetic acid and abscisic acid concentrations during development of the Ginkgo biloba L. ovule

SummarySeasonal changes in the concentrations of indole-3-acetic acid (IAA) and abscisic acid (ABA) in the endosperm and integument of the ovule of Ginkgo biloba L. were analysed by GC-MS using [d5]-IAA and [d6]-ABA as internal standards. The concentration of IAA in the endosperm increased rapidly during the period of rapid growth, and was closely correlated with the growth rate of the ovule. The concentration of IAA in the integument was much lower than that in the endosperm, but also changed similarly. The concentration of ABA in the endosperm showed a peak after the cessation of rapid growth, and decreased during the fertilization period. The concentration of ABA in the integument also increased after the cessation of rapid growth, though slowly.

In vitro induction of autotetraploid of Roman chamomile (Chamaemelum nobile L.) by colchicine treatment and essential oil productivity of its capitulum

Chamomile is well-known medicinal plant, comprise of ca. 100 species or varieties, cultivated in Europe, Asia, Australia, and North and South America (Hikawa 1998; Franke and Schilcher 2005). Two of these species, the annual herbaceous German chamomile (Matricaria recutita L., syn. Chamomilla recutita L.) and the perennial Roman chamomile (Chamaemelum nobile L., syn. Anthemis nobilis L.) are the most economically important in the production of essential oils that are used for pharmaceuticals and cosmetics (Franke and Schilcher 2005). The composition of essential oils is quite different between these two species. The major components of essential oil of German chamomile are sesquiterpenoids such as chamazulene, bisabolol, and its oxide, while those of Roman chamomile are hemiterpenoids such as angelic acid and its esters, and monoterpenoids like α-pinene (Omidbaigi et al. 2004; Franke and Schilcher 2005). It is of interest to breed to increase essential oil productivity in both species because of their low oil yield by steam distillation ca. 0.2~1.5% (v/w) (Hikawa 1998). Chromosome doubling is a powerful breeding method for increasing the productivity of secondary metabolites. To date, several plants have been successfully bred to increase production of secondary metabolites by chromosome doubling. For example, the productivity of tropane alkaloids has been increased to 122.5% in tetraploid plants compared to diploids in Hyoscyamus niger (Lavania and Srivastava 1991). In Artemisia annua, tetraploid hairy roots produced up to six times more sesquiterpene artemisinin than the diploid original (Jesus-Gonzalez and Weathers 2003). Moreover, enhanced productivities of essential oil as a secondary metabolite in tetraploid herbal plants have been reported, e.g., caraway (Dijkstra and Speckmann 1980) and Japanese peppermint (Janaki-Ammal and Sobti 1962). In German chamomile, tetraploid plants have also been bred since 1960s because tetraploid plants were well known for their large-sizedmorphology and increased productivity of essential oils (Franke and Schilcher 2005). However, the productivity of essential oil by tetraploid plants and the establishment of efficient formation of tetraploid plants in Roman chamomile remain unreported. In this paper, we tried to establish an efficient chromosome doubling system in Roman chamomile by using an in vitro culture system. We also characterized the morphological phenotypes of mature regenerated tetraploid plantlets. In addition, the content and composition of essential oils in those plants are discussed.

Anatomical and histological changes in developing silverberry (Elaeagnus multiflora var. gigantea L.) fruit

Summary The growth of silverberry (Elaeagnus multiflora var. gigantea L.) fruit, including the calyx tube, which becomes edible, and the ovary wall was investigated in relation to their cell structure. Samples of flowers at anthesis to mature fruits were collected each week from mature trees growing in Japan, replicated over two seasons. Anthesis-to-fruit maturity took 6 – 7 weeks. Cell division in the parenchyma of the calyx tube terminated approx. 3 weeks after anthesis in late April, coinciding with the appearance of tannin cells. Cell division in the ovary wall was not observed after anthesis. Examination of transverse sections of the calyx tube revealed that the sizes of the eight vascular bundles, radially distributed at regular intervals, increased as the fruit developed. Vascular tissues in the calyx tube and ovary did not branch into other tissues. Cells in the outer periphery of the vascular bundles in the calyx tube expanded more than cells in the inner portion. Parenchymal cells of the calyx tube that enlarged laterally during fruit growth became succulent, juicy, and coloured. Changes in the overall diameter and weight of fruit over time were sigmoidal, although the adjacent exterior portion of the vascular bundle in the calyx tube formed a hard shell at maturity. Cells in the ovary wall remained soft throughout fruit growth. Hence, growth and development of the edible calyx tube and the well-developed vascular system were distinctive and unique features of fruit of this species.