An Event Preceding Genome Differentiation in the A Genome Populations of <i>Scilla scilloides</i>

Abstract

Hybrids between A genome diploid plants from the Chinese and Korean populations of the Scilla scilloides complex were found. Molecular cytogenetic examination and genome size measurement showed that the hybrids were composed of two distinguishable A genomes. Genomic in situ hybridization (GISH) using mixed probes of both parental genomic DNAs could distinguish the chromosomes of each A genome in the chromosome spreads of hybrid plants. This suggests that the A genome plants of the two populations differ at the genomic DNA level. The genome size of the Korean population was 1.2-1.3 times larger than that of the Gansu population according to the area of chromosome set and fluorescence intensity in flow cytometry (FCM). Despite these cytological differences, the hybrids showed normal chromosome pairing in meiosis of pollen mother cells (PMCs), suggesting that the genomes of these two populations still belong to the same genome in terms of classical cytogenetics. Despite these genomes belonging to the same A genome, molecular signs of genome differentiation in the A genome were also found in the 5S rDNA spacer region. Southern blot hybridization of this spacer region from several populations showed that the three A genome populations were distinct from one another. Additionally, in a sequence analysis of a part of matK gene and ITS1, the three A genome populations showed population-specific sequence variations. These results suggest that the A genome populations of S. scilloides is just in the process of genome differentiation.

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

“…A length of 5S rDNA amplified by PCR (Hizume and Araki 1997) was also used for determination of genome composition. Plants of an artificial hybrid (AB hybrid) between the Japanese BB diploid and the Korean AA diploid (Araki 1971), and spontaneous hybrids of AA diploids between in the Gansu China and Korean localities (Shibata et al 2017), and tri ploids between the Japanese amphi diploid and the AA diploid of Huashan China were used for confirming the maternal inheritance of chloroplast genome.…”

“…Analyses of 5S rDNA, ITS1 and matK Total genomic DNA was extracted from a small piece of leaf from each plant having various genome compositions and in several localities following Shibata et al (2017). A 5S rDNA and ITS1 of nuclear DNA, and a part of matK of chloroplast DNA were amplified using the universal primer sets of 5SL1 and 5SL2 for a 5S rDNA repeat unit (Hizume 1993), of ITS1 and ITS2 for a ITS1 (Dams et al 1988), and of matK472F and matK1248R for a part of matK (Yu et al 2011) by a PCR with a conventional thermal cycle.…”

“…In the B genome one difference was found in a nucleotide sequence of matK, and there were the Japanese dominant sequence (Japanese B type matK) and the Chinese dominant sequence (Chinese B type matK). The Southern hybridization of spacer region of 5S rDNA indicated that the parents of amphi diploid were the Korea AA diploid and the Japanese BB diploid (Shibata et al 2017). In this study we use these molecular markers and genome size to reveal cytoplasmic and nuclear roots of amphi diploids from several localities of Japan, Korea and Taiwan.…”

“…In this study the origin of amphi diploids from several populations is determined and discussed whether the amphidiploid is monoplyly or polyphyly. Shibata et al (2017) showed that matK, ITS1, 5S rDNA and genome size could be useful for determination of the genomes and localities. Using these markers the A genome could be distinguished as three types (Korean type, Gansu China type and Huashan China type in Shibata et al 2017).…”

“…Shibata et al (2017) showed that matK, ITS1, 5S rDNA and genome size could be useful for determination of the genomes and localities. Using these markers the A genome could be distinguished as three types (Korean type, Gansu China type and Huashan China type in Shibata et al 2017). The B genome shows less variation than the A genome.…”