Karyotypes of Amphidiploid of <i>Scilla scilloides</i> Complex in Taiwan with Special Reference to Secondary Constriction of the A Genome

Abstract

Summary Several bulbs of Scilla scilloides collected at two localities in Northern Taiwan were studied for their karyotypes. All plants had 2n=34 chromosomes and their karyotypes, including the characteristic chromosomes of A and B genomes, were considered to be AABB genome constitution. The karyotype of each plant had two, three or four secondary constricted chromosomes. In all plants, two chromosomes with clear secondary constriction having an elongated thread and satellite corresponded to the b 1 chromosome of the B genome. In some plants, two or one a 2 chromosomes of the A genome had secondary constriction at the proximal region in addition to the b 1 chromosome. All plants formed, at maximum, four nucleoli with various sizes in a nucleus, indicating that they had four NORs in contrast with the number of secondary constrictions. Size variation of nucleoli seemed to correlate with incidence of secondary constriction. The variation of secondary constriction or NOR in AABB plants of Taiwan populations was discussed with AABB karyotypes in other localities.

Multiple Origin of Amphidiploids in the Complex Species of <i>Scilla scilloides</i>, Asparagaceae

“…1. Genome compositions of plants were surveyed a chromosome number and marker chromosomes of each genome such as the longest metacentric a 1 chromosome, the satellited subetelocentric a 2 and b 1 chromosomes (Araki 1971) by a conventional chromosome analysis (Hizume and Shibata 2016). A length of 5S rDNA amplified by PCR (Hizume and Araki 1997) was also used for determination of genome composition.…”

“…The amphi diploids from Okinawa Japan and Taiwan have four NORs on the satellite a 2 and b 1 chromosomes of each A and B genome (Hizume andAraki 1994, Hizume andShibata 2016). A single type of ITS1 was amplified by PCR from the amphi diploids having four NORs from Okinawa Japan and Taiwan and was suggesting a replacement of one type of rDNA in an intergenomic hybrid or an amphi diploidal genetic condition.…”

“…In situ hybridization of 45S rDNA probe revealed that a disappearance of secondary constriction on the a 2 chromosome in amphi diploids was caused by a loss of most 45S rDNA repeats from the a 2 chromosome (Hizume and Araki 1994, Hizume and Shibata 2001, Choi et al 2008. The amphi diploid populations in Okinawa, Japan and Taiwan have four secondary constrictions or NORs of both genomes (Hizume and Araki 1994, Hizume andShibata 2016). Other cytological difference is not detected among the amphidiploids in various localities.…”

“…Genomic in situ hybridization (GISH) discriminated chromosomes of each the genome in amphidiploids (2n=34=AABB) and suggested a differentiation in genomic DNA level between two genomes (Hizume andAraki 1996, Hizume andShibata 2001). Extensive cyto geographical studies have revealed that diploids, tri ploids, tetraploid, hexaploid and pentaploids with various combinations and compositions of two genomes (Araki 1972, Ihara 1977, Araki 1985, Choi and Bang 1990, Yu and Araki 1991, Uchino et al 1992, Yu et al 1992, Ding et al 1998, Horiuchi et al 1999, Choi et al 2004, Ding et al 2005, Hizume and Shibata 2016. The AA diploids distribute in Korea, China and Taiwan, and the BB diploids distribute in Japan and East central China.…”