臺灣錦葵科植物染色體之研究

Chromosome Study of the Malvaceae in Taiwan

本試驗以醋酸洋紅壓碎法製片，觀察台灣產7屬15種1亞種1變種錦葵科植物之根尖細胞有絲分裂中期之染色體，並進行核型分析。染色體數目上野棉花、梵天花2n=28，為多倍體起源之二倍體；木芙蓉、山芙蓉2n=92、黃槿2n=96，為基數x=16之六倍體，但前兩者缺失4條染色體成為非整倍體；繖楊2n=26，為非整倍數之二倍體；香葵2n=6x=72，賽葵2n=2x=24，金午時花屬中除了細葉金午時花、圓葉金午時花為2n=4x=28，薄葉金午時花、澎湖金午時花為2n=4x=32之外，其餘四種均為2n=2x=14。本科植物中，染色體最小的為黃槿0.53µm，最大的則是繖楊的4.61µm；B染色體僅存在於金午時花一種，而隨體出現在山芙蓉（第12對）、薄葉金午時花（第8對）及野棉花（第6對）之短臂上，分別屬a型、b型及c型隨體。以核型來看，錦葵科植物染色體有86%為兩臂對稱的M、m及sm型染色體，此意示著本科為演化歷史上較古老或原始的植物。由核型分析可知，金午時花屬最原始，賽葵屬為最特化之植物。在金午時花中以擬金午時花較原始，而薄葉金午時花及澎湖金午時花為最進步之種類。木槿族的繖楊屬為較原始的類群，其外部型態特徵、染色體特徵、數目及核型組成均與其他各屬有極大的差異，故應將之提升至族的地位較妥當。 The materials or 15 species 1 subspecies and 1 variety of 7 genera of Malvaceae were collected throughout Taiwan Island and studied for chromosome characteristics or somatic cells, using acetocarmine squash technique. The chromosome numbers of Urena lobata and U. procumbens arc 2n=28. They are the present diploid and the paleopolyploid drived from the ancestor by polyploidization. Three species of Hibiscus mutabilis (2n=92). H. taiwanensis (2n=92) and H. tiliaceus (2n=96) are hexaploid based on x=16. However, the former two species are aneuploid evolved by losing four chromosomes. The chromosome number of Thespesia populnea is 2n=26 and is considered as a diploid. Moreover, the chromosome numbers of Ahelmoschus moschatus is 2n=-6x=72, Malvastrum coromandelianum 2n=2x=24, Sida acuta and S. cordifoloa 2n=4x=28. S. mysorensis and S. veronicarfolia 2n=4x=32, and the other 4 species of Sida 2n=2x=14. In these plants of the family, the smallest chromosome (0.53 µm) is found in Hibiscus tiliaceus and the biggest (4.61 µm) in Thespesia populnea. B chromosomes arc only found in sida rhombifolia ssp. rhombifolia. Satellites are found on the short arm of chromosome in Hibiscus taiwanensis (the 12th pair of chromosomes). Sida mysorensiss (the 8th pair) and Urena lobata (the 6th pair) and are considered as a. band c types respectively. Based on the karyotype characteristics. 86% of the chromosomes are assigned as M. m and sm types, which are more or less symmetrical for the two arms of the chromosomes, and are considered primitive for this family. The karyotypes of Sida are most primitive and Malvastrum are most derived. In the genus Sida. S. rhomboidea is the most primitive, whereas both S. mysorensis and S. veronicaefolia are most derived. In the tribe Hibisceae, Thespesia is the most primitive genus. Its morphological and chromosomal characteristics, chromosome number and the karyotype components are different from the other genera of its tribe. Therefore, it is appropriate to be removed from that tribe and treated as the tribe Thespesiceae.

The materials or 15 species 1 subspecies and 1 variety of 7 genera of Malvaceae were collected throughout Taiwan Island and studied for chromosome characteristics or somatic cells, using acetocarmine squash technique. The chromosome numbers of Urena lobata and U. procumbens arc 2n=28. They are the present diploid and the paleopolyploid drived from the ancestor by polyploidization. Three species of Hibiscus mutabilis (2n=92). H. taiwanensis (2n=92) and H. tiliaceus (2n=96) are hexaploid based on x=16. However, the former two species are aneuploid evolved by losing four chromosomes. The chromosome number of Thespesia populnea is 2n=26 and is considered as a diploid. Moreover, the chromosome numbers of Ahelmoschus moschatus is 2n=-6x=72, Malvastrum coromandelianum 2n=2x=24, Sida acuta and S. cordifoloa 2n=4x=28. S. mysorensis and S. veronicarfolia 2n=4x=32, and the other 4 species of Sida 2n=2x=14. In these plants of the family, the smallest chromosome (0.53 µm) is found in Hibiscus tiliaceus and the biggest (4.61 µm) in Thespesia populnea. B chromosomes arc only found in sida rhombifolia ssp. rhombifolia. Satellites are found on the short arm of chromosome in Hibiscus taiwanensis (the 12th pair of chromosomes). Sida mysorensiss (the 8th pair) and Urena lobata (the 6th pair) and are considered as a. band c types respectively. Based on the karyotype characteristics. 86% of the chromosomes are assigned as M. m and sm types, which are more or less symmetrical for the two arms of the chromosomes, and are considered primitive for this family. The karyotypes of Sida are most primitive and Malvastrum are most derived. In the genus Sida. S. rhomboidea is the most primitive, whereas both S. mysorensis and S. veronicaefolia are most derived. In the tribe Hibisceae, Thespesia is the most primitive genus. Its morphological and chromosomal characteristics, chromosome number and the karyotype components are different from the other genera of its tribe. Therefore, it is appropriate to be removed from that tribe and treated as the tribe Thespesiceae.