Two Novel Self-compatible S Haplotypes in Peach (Prunus persica)

Abstract

Peach (Prunus persica) as a species is self-compatible (SC), although most other Prunus fruit tree species are partially or fully self-incompatible. We previously identified 3 mutated S haplotypes, S 1 , S 2 , and S 2m, that confer self-compatibility on commercial peach cultivars for fruit production. In this report, we identified 2 novel SC S haplotypes, S 3 and S 4 , among 130 peach cultivars and strains consisting mainly of ornamental cultivars and wild strains. The S 3 haplotype was found only in ornamental cultivars, while the S 4 haplotype was found mainly in wild strains. S-RNases in the S 3 and S 4 haplotypes appeared to have no defects in their primary structures. S haplotype-specific F-box (SFB) sequences were also present in the S locus downstream of the S 3 -and S 4 -RNases. These SFB sequences were in a reverse transcriptional orientation as has been reported in most other functional Prunus S haplotypes; however, both SFB sequence, obtained by removing the inserted sequence, encodes a typical SFB. Based on the 3 previously identified peach S haplotypes, we supposed that the S 3 and S 4 haplotypes were also SC pollen part mutant (PPM) S haplotypes. Here, we also discuss possible reasons for all peach S haplotypes identified so far having the PPM SC S haplotype.

Identification and characterization of S-RNase genes and S-genotypes in Prunus and Malus species

“…As a result, two out of the four DNA fragments were identical to S 1 -and S 2 -RNase alleles. The remaining two DNA fragments were identical to S 3 -and S 4 -RNase alleles, which were recently reported by Hanada et al (2014). Of the 113 peach cultivars analyzed, 9, 70, 5, 7, 18, and 4 belonged to S 1 S 1 , S 1 S 2 , S 1 S 3 , S 1 S 4 , S 2 S 2 , and S 2 S 4 genotypes, respectively (Table 1).…”

“…Here, two additional alleles, SFB 3 and SFB 4 , have been identified in peach. A more recent study reveals that SFB 3 is only present in ornamental cultivars, while SFB 4 is identified mainly in wild strains (Hanada et al 2014). However, our study indicates that the SFB 3 allele is present in both ornamental cultivar Juhuatao and edible cultivars such as Disertered and Wanpantao, and the SFB 4 allele is present only in cultivars.…”

“…In peach, two different S-haplotypes have been initially identified in cultivars (Hegedu¨s et al 2006;Tao et al 2007). More recently, two additional S-haplotypes have been reported (Hanada et al 2014). Whereas, over 20 S-haplotypes are reported in other Prunus species such as almond, sweet cherry, plum, apricot, and Japanese apricot (Ushijima et al 2003(Ushijima et al , 2004Yamane et al 2003a, b;Romero et al 2004;Vaughan et al 2006;Zhang et al 2007;Wu et al 2009Wu et al , 2013.…”

Phylogenetic relationships among the first and second introns of selectedPrunus S-RNase genes

“…Peach and almond speciation presumably occurred as the progenitor species expanded its distribution to humid regions of eastern Asia and dry regions of western Asia, respectively. Hanada et al (2014) reported that the S1 haplotype in peach is a pollen part mutant version of the almond Sk haplotype.…”

“…When the S-allele haplotype of the pollen is identical to either of the two S-alleles present in diploid pistil, pollen tube growth will be arrested (Pimienta et al 1983;Channuntapipat et al 2001;Kodad et al 2008b) and fertilization prevented. The term 'S-haplotype' is used to describe variants of the S-locus, whereas the term ''S-allele'' is used to describe the variant of a given S-locus gene (Hanada et al 2014). The S-locus encodes a series of glycoproteins known as S-RNases with ribonuclease activities in the style, as well as an F-box gene (SFB) that functions in the pollen (Ushijima et al 2003).…”