Inheritance of flower characteristics and distant hybridization barriers of Torenias
Date Issued
2010
Date
2010
Author(s)
Wei, Tzu-Yao
Abstract
Wishbone flower (Torenia fournieri Linden) is one of the most important annual bedding plants in Taiwan during spring to summer. Four Taiwan-native Torenia species could be used for breeding, to meet the potential demands. However, information of possible hybridization barriers of Torenia is presently limited. This thesis studied self- and interspecific pollination between T. fournieri, T. flava Buch.-Ham. ex Benth., T. concolor Lindl., and T. benthamiana Hance. We observed 1) pollen tube growth within interspecific pistil, 2) growth of hybrid endosperm and embryo, and 3) growth of capsules after self- or interspecific pollination, to clarify hybridization barriers in Torenia. Interspecific progenies between T. fournieri and T. baillonii Godefr. were obtained, and their floral traits were investigated.
Under greenhouse conditions, pollen tubes of T. flava and T. fournieri ‘Clown Blue’ in styles of T. flava could be observed at 4 h after pollination by means of fluorescence, while no pollen tubes of T. fournieri ‘Clown Rose’ was found. Pollen tubes of T. concolor and T. benthamiana could be observed in style of T. fournieri ‘Clown White Blush’ and ‘Clown Blue’ at 4 h after pollination, but less clear for T. benthamiana.
Capsule lengths of T. fournieri ‘Clown Blue’, ‘Clown Rose’, and T. flava were measured after self- or interspecific pollination. In interspecific pollinations, capsule length did not increase at 5, 6, and 4-6 days after pollination in T. fournieri ‘Clown Blue’, ‘Clown Rose’, and T. flava, respectively. In contrast, capsule length increased after self-pollination in T. fournieri ‘Clown Blue’, ‘Clown Rose’, and T. flava for 5, 10, and 9 days, respectively, and were longer than interspecific pollinated capsules.
Capsules and seeds were harvested from T. fournieri ‘Clown’ cultivars after self- or interspecific pollination with T. flava, T. concolor, and T. benthamiana. Except when T. fournieri ‘Clown Rose’ and ‘Clown Blue’ were used as female parents, time to capsule harvest did not differ between tested interspecific pollination and self-pollination combinations. No seed was collected in most of the tested interspecific combinations, but 4 and 8 seeds per capsule were harvested when T. fournieri ‘Clown Burgundy’ and ‘Clown Violet’ were used as female parents, respectively.
Unpollinated and self-pollinated T. fournieri ‘Clown Violet’ capsules, and those cross-pollinated with T. concolor and T. benthamiana were collected at 4, 8, and 16 days after pollination (DAP) and sectioned. At 4 DAP, self-pollinated capsules had longer placenta than unpollinated ones. Ovules in unpollinated capsules were small, whereas larger ovules and more ovular growth were identified in self-pollinated and cross-pollinated capsules. Developing ovules were only located in the upper halves in capsules of T. fournieri ‘Clown Violet’ pollinated with T. benthamiana. At 8 DAP, no significant changes were observed in unpollinated capsules, but significant placental and ovular growth were identified in self- and cross-pollinated capsules. At 16 DAP, no changes were observed in unpollinated capsules, whereas embryos could be clearly observed in self-pollinated capsules and those cross-pollinated with T. benthamiana. Meanwhile, empty ovules were observed in capsules pollinated with T. concolor.
Ovules had more endosperm development in self-pollinated capsules than cross-pollinated ones. At 8 DAP, embryo sac fully occupied by endosperm were observed in self-pollinated T. fournieri. Degenerating endosperm were observed in T. fournieri cross-pollinated with T. concolor, whereas endosperm developed slower after cross-pollinated with T. benthamiana. At 16 DAP, well-developed embryo and endosperm were observed in self-pollinated T. fournieri. Degenerated endosperm and globular embryos were observed in T. fournieri cross-pollinated with T. concolor, Contrastly, embryos at torpedo or cotyledonal stages with a less developed endosperm were observed in T. fournieri cross-pollinated with T. benthamiana.
T. fournieri ‘Clown’ cultivars were used to pollinate with T. baillonii. More seeds were collected when T. fournieri ‘Clown Rose’ was used as female parent. Only few progenies were obtained when T. fournieri ‘Clown White Blush’, ‘Clown Violet’, ‘Clown Plum’, ‘Clown Blue & White’, and ‘Clown Rose’ were used as female parent. The hybrid progenies were semi-prostrate and had racemes. Corolla tube color were mainly violet, and corolla color were mainly yellow combined with red-purple patterns. Colored pattern on corolla were mainly similar to those of seed parents.
Subjects
Torenia concolor
Torenia benthamiana
Torenia flava
endosperm
embryo
Type
thesis
File(s)![Thumbnail Image]()
Loading...
Name
ntu-99-R96628131-1.pdf
Size
23.53 KB
Format
Adobe PDF
Checksum
(MD5):6e4fe70d74712891735ae9b8406c3ff9