Estimation of Self-incompatibility Genotypes of Citrus Cultivars with Got-3 Allozyme Markers

Abstract

Self-incompatibility (SI) in Citrus is known in cultivars and plants of pummelo, pummelo relative, and mandarin; however, the detailed mechanism of self-incompatibility and the allelic diversity of the SI gene (S) are not known because of the presence of barriers such as nucellar embryony, male sterility, and a long juvenile phase. Thus, there is little information on S genotypes of Citrus cultivars at present. In this study, the S genotypes of Citrus cultivars were estimated with the aid of allozymes produced by a glutamate oxaloacetate transaminase isozyme gene (Got-3), which appeared to link to the S gene. Of twenty-two F 1 progenies from eleven crosses and their reciprocal crosses with eight monoembryonic SI cultivars, including 'Banpeiyu' pummelo, three F 1 progenies from three crosses and three from reciprocal crosses showed segregation distortion for the Got-3 gene, suggesting the presence of the same S alleles in the cultivars used for the reciprocal crosses. Defining the 'Banpeiyu' genotype as S 1 S 2 , the genotype was estimated as S 1 S 3 for 'Tosa Buntan', S 4 S 5 for 'Hassaku', S 6 S 7 for 'Yuge-hyokan', and S 1 S 6 for 'Shishiyuzu'. Further allozyme analyses for segregation distortion in progenies from eight crosses with eight monoembryonic SI cultivars suggested the possibility that 'Hyuganatsu' has S 1 allele, while those from 15 crosses between the eight monoembryonic SI cultivars and five polyembryonic self-compatible cultivars suggested the possibility that 'Rough lemon' has S 1 allele. The estimated genotypes, consisting of two of the nine alleles (S 1 to S 8 and S f ) in these Citrus cultivars, may be useful for further estimation and determination of S genotypes in Citrus cultivars and plants.

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

“…7, average of 17.7 pollen tubes penetrated the style base. q The estimated S genotype within parentheses is based on the report of Ngo et al (2011), and the others used the following reports:…”

“…Segregation distortion in several progenies suggested that Got-1 and Got-3 genes appeared to link with an S gene, since segregation distortion in the progenies was detected in reciprocal crosses and only when the pollen parents were heterozygous for the genes. Based on the presence or absence of distorted segregation in progenies from 52 crosses with many Citrus cultivars, Ngo et al (2011) estimated the existence of eight alleles for the S gene. Ngo et al (2010) carried out controlled pollination with a restricted number of pollen grains (about 100 pollen grains per stigma) to verify the estimated S genotypes of the Citrus cultivars on the basis of pollen tube growth behavior in the pollinated styles, and reported that pollen tube behavior coincided with the predicted semi-compatible crosses and fully compatible crosses.…”

“…To estimate the S genotypes based on joint segregation analysis of Got-3 and S genes in Citrus (Ngo et al, 2011;Wakana et al, 1998), a large number of zygotic seedlings were necessary for statistical analyses because of the linkage of the two genes with the relatively long distance of 31 cM. Reciprocal crossings between two cultivars are a necessary to estimate the existence of an S allele common to both cultivars by joint segregation analysis.…”

Morphology of Sterile Anthers and Inheritance of Cytoplasmic-genetic Male Sterility in Zygotic Seedlings of Polyembryonic Acid Citrus

“…Seedling morphology, such as leaf shape and thorniness, was carefully compared with nucellar seedlings obtained from polyembryonic seeds. Only those suspected to be nucellar were analyzed for hybridity with three glutamate oxaloacetate transaminase isozyme genes, Got-1, Got-2, and Got-3, according to the procedure described by Rahman et al (2001) and Ngo et al (2011). Zygotic seedlings with the hybrid characteristics were grafted onto 20-year-old 'Miyagawa-wase' satsuma mandarin trees to enhance the growth of the seedlings.…”

Unreduced 2n Pollen Production in ‘Nishiuchi Konatsu’ Hyuganatsu as Inferred by Pollen Characteristics and Progeny Ploidy Level

“…Hyuganatsu occupies an important position as a late-season citrus cultivar in the fruit industry of Miyazaki prefecture. Hyuganatsu substantially has neither parthenocarpic traits nor self-compatibility (Miwa, 1951), for which approaches to genetic and molecular bases have recently begun Ngo et al, 2011;Uchida et al, 2012). As a result of these characteristics, a pollinizer is required to set the fruits, which ultimately contain many seeds (Yamamoto et al, 1995).…”