|其他题名||Studies on cytology,reproductive biology and pollen morphology of Petrocosmea (Gesneriaceae) from China
|其他摘要||Petrocosmea (Oliv.) belongs to the family Gesneriaceae. Up to now, litreautre and researches related to Petrocosmea are limited both from home and abroad. The thesis includes investigation and introduction of the genus Petrocosmea from the wild especially from southwesten China. Preliminary studies on cytology, reproductive biology and pollen morphology of the genus Petrocosmea and some species from other genera were conducted. The main progresses are briefly summarized as follows:
1. Resource investigation，introduction and cultivation
The genus Petrocosmea mainly distributes in Yunnan, China and most of the species grow in the crevices of cliffs. Most plants in the genus prefer shady and humid habitat, where mosses，ferns and shrubs are commonly found. Based on growth observation of plants introduced from the wild, most species of Petrocosmea are growing well even in infertile soil and crevice. However, species from the genus Petrocosmea are usually obeserved growing in a very small area in the wild. It is obvious that human activities can have a huge negative impact on the plants’ habitat. It is suggested that effective conservation action should be taken.
2. Preliminary studies on breeing system
Researches of breeding system on two endemic species of Petrocosmea to Yunnan were conducted. The studies including floral morphology, pollen viability, stigma receptivity, hand pollination and out-crossing index. P. sericea and P. minor bloom in the period between July and October when cultivated in the green house. On the 6th day after the anther of P. sericea crazed, the highest percentage of pollen viability was observed. On the 6th day after full blossom, the stigma of P. sericea showed receptivity. On the 5th day after the anther of P. minor crazed, the highest percentage of pollen viability was noticed. On 9 to 10 days after full blossom, the stigma of P. minor showed receptivity. Afterwards, the stigma P. minor became non-receptive until the flower was withered. According to Dafni(1992), the out-crossing index of the two species is 4, which means they are partially self-compatile and need pollinators sometimes. No fruit was produced after hand pollination.
3. Reproductive biology
(1) Cutting propagation
A result of nearly 100% rooting rate of cutting propagation showed in 12 species of Petrocosmea. In winter, cuttings were less affected by diseases but had a relatively low rooting speed.
(2) Tissue culture
Tissue culture was conducted on two endemic species of Petrocosmea to Yunnan. The results indicated that the most effective disinfection method for P. sericea was 70% ethanol 10s+0.1%HgCl25min; P. coerulea 70% ethanol 10s+0.1%HgCl24min. The progress of inducing adventitious buds were extremely slow, giving a hint to us that there probably be some inhibit factors.
4. Cytological studies
The chromosome numbers of twelve species of the genus Petrocosmea Oliver from China are reported, of which seven are reported for the first time. The results are highly consistent within Petrocosmea, and the chromosome numbers of all the species observed here are 2n=34. The chromosomes of the twelve species are relatively small in size. Satellites are observed from time to time.
5. Pollen morphological studies
Pollen of 38 species out of 23 genera was examined using scanning electron microscopy. Compared with other genus, there was little difference between species relating to aperture types, exinetypes and grain size, which indicating that Petrocosmea is a naturally defined genus.
The results of pollen morphological studies showed that reticulate was the most commonplace exine sculpture patterns among Gesneriaceae, as well as perforate and foveolate. The main differences were observed through exine sculpture patterns and coluprate. Besides, the same species from different population had different exine sculpture patterns.|
季慧. 国产石蝴蝶属植物的细胞学、繁殖生物学和花粉形态的研究[D]. 昆明植物研究所. 中国科学院昆明植物研究所,2008.