Determination of Self-incompatible Citrus Cultivars with S1 and/or S2 Alleles by Pollination with Homozygous S1 Seedlings (S1S1 or S2S2) of ‘Banpeiyu’ Pummelo

Abstract

Gametophytic self-incompatibility (SI), an important character for breeding seedless cultivars of Citrus, is known in pummelo, mandarin, and many hybrid cultivars with pummelo in their pedigrees. Only a little is known about the allelic variation in the self-incompatibility gene (S), S allele frequencies, and the genotypes of self-incompatible and semi-self-compatible cultivars. In this study, pollination of 'Banpeiyu' S 1 seedlings with 'Banpeiyu' and pollination between the S 1 seedlings were performed to determine homozygous S 1 seedlings for the S gene. Seventyeight Citrus accessions, including 55 pummelo accessions, were pollinated with each of two homozygous S 1 seedlings (S 1 S 1 and S 2 S 2 ). Pollen tube arrest in the style base of their pollinated pistils indicated that 23 accessions, including 'Banpeiyu', have an S 1 allele each and 16 accessions, including 'Banpeiyu', have an S 2 allele each. Frequency of accessions with S 1 allele was 29.9% (23 of 77 accessions examined) and S 1 allele frequency was 16.4% (23 of 140 alleles excluding S f allele). Frequency of accessions with S 2 allele was 21.3% (16 of 75 accessions examined) and S 2 allele frequency was 11.6% (16 of 138 alleles excluding S f allele). Pummelo accessions collected from Kagoshima Prefecture had S 1 alleles with two and half times higher frequency (56.3%) than that in all accessions examined. Of the 79 accessions, six accessions ('Banpeiyu', 'Iriki Buntan', 'Kaopang', Nagashima Buntan No. 6, Nagashima Buntan No. 7, and 'Soyu') were S 1 S 2 genotypes. The Citrus cultivars, whose S genotypes have been fully determined in this study, were

Isolation and Characterization of <i>S-RNase</i>-homologous Genes Expressed in Styles in ‘Hyuganatsu’ (<i>Citrus tamurana</i> hort. ex Tanaka)

“…After T2 RNase sequences were obtained, similar sequences were also identified in the citrus EST database using tblastx in NCBI. Sequence Kim et al (2011) and Zhou et al (2018). Self-compatible cultivars are automatically assigned an S f allele, which is thought to be present based on the inheritance of self-compatibility (Vardi et al, 2000).…”

“…Therefore, the S 1 -haplotype of 'Haruka' could be inherited from 'Hyuganatsu'. Among the cultivars that do not contain CtRNS3, clementine, 'Nomabeni Hassaku', and 'Okitsu Wase' did not have an S 1 allele (Kim et al, 2011). Because the CtRNS3 distribution matched its presence/ absence on the S 1 allele, it is plausible that CtRNS3 is the S 1 allele in citrus.…”

“…x S ? is not S 2 , S 4 , or S 5 (Kim et al, 2011;Zhou et al, 2018 data of T2 RNase genes in other angiosperms, which included S-RNases in Rosaceae, Solanaceae, and Plantaginaceae, were retrieved from DDBJ/EMBL/ GenBank databases (Suppl. Table 1).…”

“…Kim et al (2011) defined the SI genotype (S genotype) of 'Banpeiyu' as S 1 S 2 and tried to determine the S genotypes of some citrus cultivars using homozygous (S 1 S 1 or S 2 S 2 ) seedlings derived from a bud pollination of selfed 'Banpeiyu'. 'Hyuganatsu' and 'Tosabuntan' reportedly contain the S 1 allele because they were incompatible with the pollen grains of S 1 homozygous progeny (Table 1; Kim et al, 2011). 'Haruka' is a chance seedling of 'Hyuganatsu' and its pollen parent was recently identified as 'Natsudaidai' (Shimizu et al, 2016).…”

In Vitro Self-incompatible-like Response Applied for Protein Identification and Gene Expression Analysis in Citrus Cultivars, Banpeiyu and Hyuganatsu

“…Since ROS has been proposed as a key inducer of PCD (De Pinto et al, 2012), it is possible that the ROS cascade reaction, which was induced by SI-like treatment in 'Banpeiyu' and 'Hyuganatsu' pollen tubes, is a trigger for the PCD process. The S genotype of 'Banpeiyu' has been determined as S 1 S 2 by number of pollination experiments, and the S genotype of 'Hassaku' has been estimated as S 4 S 5 (Kim et al, 2011). Therefore, in this study, the candidates for SI-related proteins derived from the differences between SI-and C-like treatments with different S genotypes.…”