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Occurrence of Spontaneous Polyembryony in Lilium lancifolium Thunb
Ye-Su, Song,Kim, Jong-Hwa,Wakana, Akira FACULTY OF AGRIC PUBLICATIONS-KYUSHU UNIV 2017 Journal of the Faculty of Agriculture, Kyushu Univ Vol. No.
<P>We examined spontaneous polyembryony in Lilium lancifolium Thunb. by determining the occurrence of polyembryonic seeds in intraspecific crosses and open pollination, and by analyzing the genetic origins of polyembryos with simple-sequence repeat (SSR) markers. Forty-one polyembryonic seeds (0.2% of total) were detected from 17,583 seeds. Of the polyembryonic seeds, 36 were duplets and five were triplets. Eighteen seedling sets (three triplets and 15 duplets) were cultured and grown to maturity. Flow cytometry revealed that all were diploids, and results of analyses with SSR markers indicated that all the multiple embryos, except for two triplet seeds, originated from a zygotic embryo through cleavage embryony. The SSR profiles confirmed that the seedlings from polyembryos resulted from cross-fertilizations and did not from unfertilized somatic embryos. Six seedlings rescued from the two triplets occurring in 2x x 3x combinations were heterozygous with respect to SSR, and thus they may have their origin in multiple embryo sacs and/or polyspermy. The occurrence of polyembryonic seeds was remarkably greater in one accession collected from Wan-do (Wan island) than the others. This suggested that the frequency of polyembryony depends on the genotypes of L. lancifolium.</P>
Jung-Hee Kim,Mayumi Sato,Akira Wakana,Fuka Takamatsu,Kaori Sakai,Masayoshi Shigyo,Jun-ichiro Masuda 한국원예학회 2021 원예과학기술지 Vol.39 No.6
Gametophytic self-incompatibility, one of the key characteristics for breeding seedless Citrus cultivars, occurs in pummelo (Citrus maxima), mandarin (Citrus reticulata), and their hybrid cultivars. Allelic variation in Citrus was reported for the self-incompatibility gene (S); however, S allele frequencies and S genotypes of full- and semi-self-incompatible cultivars have been reported for a small number of alleles. To extend our knowledge of S alleles, we tested 146 Citrus accessions, including 82 pummelo accessions, for S9 and S10 alleles. Each accession was pollinated with homozygous S₁ seedlings of ‘Hirado Buntan’ pummelo (S9S9 and S10S10). The pollen tube growth arrest in the lower styles of their pollinated pistils indicated that four accessions, including ‘Hirado Buntan [Citrus maxima (Burm.) Merr.]’, have the S9 allele and five accessions, including ‘Hirado Buntan’, have the S10 allele. The percentage of accessions with the S9 allele was 3.2% (4 of 126 accessions examined), and the S9 allele frequency was 1.8% (4 of 217 alleles, excluding the Sf allele). The percentage of accessions with the S10 allele was 3.9% (5 of 127 accessions examined), and the S10 allele frequency was 2.3% (5 of 217 alleles, excluding the Sf allele). Japanese mandarin (another sources of S alleles) and its relatives had neither the S9 nor the S10 allele. Pummelo accessions had S9 and S10 alleles at higher rates of 2.9% (2 of 70 accessions examined) and 7.0% (5 of 71 accessions examined), respectively. ‘Kabusu’ sour orange (a pummelo-mandarin hybrid; Citrus aurantium) and ‘Kikudaidai’ (a sour orange relative; Citrus canaliculata) had S9 alleles. These results suggested that the two alleles originated from pummelo (the main sources of S alleles). The S genotypes with S9 and/or S10 alleles were fully determined in ‘Hirado Buntan’ (S9S10), ‘Kabusu’ sour orange (SfS9), the ‘Kikudaidai’ (S9S11) sour orange hybrid, and two local pummelo plants. The results of our study suggest that in comparison with the other S alleles reported, the pummelo plants with low frequencies of S9 and/or S10 alleles contributed to very low rates of evolution and development of Citrus species and cultivars during the long history of citrus cultivation, except for those generating sour oranges (Citrus auratinum), which are used as root stocks, and for flesh and rind processing and ornamental plants. Finally, we examined the degree of self-incompatibility between S9 and S10 alleles in the lower part of styles of S₁ seedlings of ‘Hirado Buntan’ and Citrus accessions with S9 and/or S10 alleles. The result indicated no difference in the self-incompatibility reaction between the two alleles.