Seeds are seldom obtained in the crosses between chrysanthemum cultivars and diploid wild species in Dendranthema, which seriously influences utilization of excellent genes from those wild speices. In the present study, with an aim to reveal the factors leading to infertility in the crosses between chrysanthemum cultivars and wild species, we carried out the interspecific hybridization between D. grandiflorum ‘JinlingHuangyu’and D. avandulifolium, tested pollen viability of male parent, examined germination behavior of
pollen grains on the stigmas after pollination, and observed embryo development. It was found that pollenviability of D. lavandulifolium was 11.2% just before pollination, no pollen grains germinated on the stigmas during 4 h after pollination and only 7.5 pollen grains germinated on each stigma at 8 h after pollination. At 12 h after pollination, the number reached the highest value, 16.1. At 24 h and 48 h after pollination, the number was quickly decreased to 3.2 and 2.4, respectively. In addition, most pollen grains germinated abnormally on the stigmas and many pollen tubes stayed on the stigmaspsurface and failed to enter ovaries. At 8 d after pollination, normal globular embryos were observed only in 12.0% ovaries. Thereafter, only
abnormal embryoswere observed in some ovaries, and as a consequence, no seedswere obtained in the cross. However, seed set of female parent under open pollination conditions was as high as 42.3%. These results suggest that both pre- and post-fertilization barriers, i. e. only a few germinated pollen grains on the stigmasand abnormal germination ofmost pollen grains before fertilization aswell as degeneration of a large number of embryos after fertilization, may be the main factors resulting in infertility in the cross.
Colchicines were employed to induce polyploid plantlets of Oncidium during ropagation of protocorm-like bodies ( PLB s) in liquid culture. A lot of polyploid plantlets were obtained by this technique.The results showed that the PLBs cultured in the medium contained higher concentration of colchicines got
harmed more severely and the rate of ployploid plantlets was bigger with higher concentration of colchicines or longer time of treatment . The biggest rate of polyploid plantlets regenerated from the PLBs could reach to 46.7%. The mixoploid could be produced under the condition of lower concentrations of colchicines and short time of treatment. The tetraloid plantlets were shorter and stronger and leaves changed broad and thick. The diameter of lower epidermal stomata in the tetraploid was a little bigger than the one in the diploid. The cell nucleus of leaf lower epidermal became bigger and approached to cell wall. The number of chromosomes in root tip cells of the polyploid plantlets were doubled.
Flavonoids are the main group of polyphenols in apple fruit, which have a variety of physiological activities positive to human health. Thirty-four flavonoids in apple fruit have been reported, which belong to 5 classes, flavanols, flavonols, dihydrochalcones, anthocyanins and flavanonols. The composition and concentration of flavonoids in apple fruit varied across both apple varieties and the parts of app le fruit. Usually, both the sorts and the concentration of flanonoids in app le peel are obviously more than those of flanonoids in apple flesh. The concentration of flanonoids in app le fruitmay change during its development, maturation and storage. In generally, flavonoids in apple fruit were determined by HPLC with diode array detector or UV detector, and could be characterized by HPLC-MS.