- 學位論文
臺灣草苺染色體倍增及其與栽培種草苺之種間雜交
Studies on Chromosome Doubling of Fragaria hayatae Makino and Interspecific Hybridization with Fragaria ×ananassa Duch.
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摘要
臺灣草苺(Fragaria hayatae Makino)為原生於臺灣之二倍體草苺，因果實較小，如欲利用，必須育出含臺灣草苺基因的多倍體，或將臺灣草苺與八倍體栽培種草苺F. ×ananassa Duch.進行正反交，期能得到五倍體雜交後代，以便進一步獲得十倍體之個體。為達此目的，本文初步進行臺灣草苺與栽培種草苺之種間雜交，以及臺灣草苺染色體倍增。 F. hayatae與F. ×ananassa互交之組合中，以臺灣草苺為母本雜交者結果率較高，以栽培種草苺為父本之單果，獲得種子數較多，而種間雜交獲得後裔不易。為提高雜交後代之存活率，進行臺灣草苺與雜交之種子的發芽試驗。臺灣草苺種子以濕冷層積處理者最早發芽，播種30天後，濕冷層積與對照處理者皆超過90%發芽率。雜交種子以濕冷層積與刻傷處理後萌芽率皆低，原因是無效種子比例過高，可能是F. hayatae與栽培種草苺雜交後，胚與胚乳發育存有障礙。 以根尖壓片法檢測草苺之染色體數。臺灣草苺染色體數為2n = 2x = 14，而F. ×ananassa ‘Taoyuan No. 3’ × F. hayatae後代中，4株為非整倍體數植株，染色體數介於44~53條，5株具56條染色體，一株為六倍體植株。雜交後代中，仍存在八倍體者，可能由於人工授粉時花粉受到汙染或是發生無融合生殖現象；另外有5株後代為非整倍體數植株，推測為雜交親本配子減數分裂異常所致。 莖頂培養臺灣草苺，初代培養基以1/2 MS搭配BA 0.5 mg．L-1 生長情形最好，適合之增殖培養基為1/2 MS + NAA 0.5 mg•L-1 + BA 0.5 mg．L-1，分株移入去除BA之增殖培養基中，促進生根。培養基中處理秋水仙素50 mg．L-1者存活8株；100 mg．L-1者存活1株。檢測7株誘變存活植株中之4株，根尖壓片之染色體數為2n = 2x = 14，無成功誘變為四倍體臺灣草苺者。
並列摘要
Taiwan strawberry (Fragaria hayatae Makino) is a diploid strawberry with small fruit and some pest resistant characteristics native in Taiwan. Polyploids and interspecific hybridization should be made for this specise’s further use. Reciprocal crosses were made between F. hayatae and F. ×ananassa Duch. in order to obtaine pentaploids, and were F. hayatae treated with colchicine, in expecting to get tetraploid plants. In the combination of Taiwan strawberry × cultivated strawberry, higher percentage of fruit set was obtained, and seed number /fruit set was higher. Progenies of the reciprocal cross between F. hayatae and F. ×ananassa were fewer than expected. To improve the survival rate of the offspring, germination test for F. hayatae and the hybrid seeds was made. Germination rate was promoted in stratified F. hayatae seeds. The seeds of stratification treatment and control of F. hayatae, both had more than 90% germination rate after sowing for 30 days. The effect of stratification and scarification were about the same in interspecific hybridization seeds. Low survival rate of interspecific hybridization seedlings was caused by low fertility seeds, especially the seeds with hollow heart might be the evidence of barrier in embryo and endosperm development. Chromosome number of root tip in F. hayatae was investigated, which was 2n = 2x = 14, and in the 10 offsprings of F. ×ananassa 'Taoyuan No. 3' × F. hayatae 4 of them were aneuploid, with the chromosome number ranging from 44 ~ 53, 5 of them were octoploid, and one plant was hexaploid. The octoploid hybrid progenies might be due to pollen contamination or apomixis. The other five aneuploidy plants suggest that there were due to disorder during miosis. In meristem culture of F. hayatae, primary medium by 1/2 MS with 0.5 mg．L-1 BA was the best growth conditions for the proliferation medium was 1/2 MS + 0.5 mg．L-1 NAA + 0.5 mg．L-1 BA. Cultured plants subcultured into the proliferation medium with BA removed, could promote rooting. Eight plantlets were obtained from a tissue culture test, which used the culture medium as further metioned with 50 mg．L-1 colchicine added. But the chromosome number of all of them were 2n = 2x = 14.
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