Molecular Basis of Self-(in)compatibility and Current Status of S-genotyping in Rosaceous Fruit Trees

Abstract

Most rosaceous fruit tree species exhibit gametophytic self-incompatibility (GSI). During the last decade, much progress has been made in identifying and characterizing the S-locus genes that control the specificity of the selfincompatible (SI) reaction in the Rosaceae. The pistil and pollen determinants of S-specificity in the Rosaceae are a ribonuclease and an F-box protein, respectively. From allele-specific sequence polymorphism of S-specificity genes, molecular S-genotyping systems have been established in various rosaceous fruit tree species. Molecular characterization of S-determinants in self-compatible (SC) cultivars has revealed defects in the S-determinants that cause SC and enabled the development of molecular markers for SC. Marker-assisted selection of SC offspring is now being successfully incorporated into breeding programs. In this paper, we summarize the current knowledge of the molecular basis of self-(in)compatibility, S-genotyping methods, and molecular markers for SC in rosaceous fruit tree species.

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

“…Mutations in the pollen S gene, however, resulted in different outcomes depending on the taxon or the family that showed the S-RNase-based GSI. Although mutations that disrupt the pollen S determinant F-box gene in Solanaceae and Plantaginaceae are supposed not to confer self-compatibility, these mutations did result in self-compatibility in Prunus (Sonneveld et al, 2005;Tao and Iezzoni, 2010;Ushijima et al, 2004;Yamane and Tao, 2009). Taken together, these findings confirm that a mutation in either S-RNase or SFB confers self-compatibility in Prunus Yamane and Tao, 2009).…”

“…Most Prunus (family Rosaceae) fruit tree species exhibit a homomorphic gametophytic selfincompatibility (GSI) system in which self/nonselfrecognition is controlled by a single multiallelic locus, called the S locus Yamane and Tao, 2009). A self-incompatibility reaction is triggered when the same S-allele specificity is expressed in both the pollen and pistil.…”

Transcriptome Analysis of Self- and Cross-pollinated Pistils of Japanese Apricot (Prunus mume Sieb. et Zucc.)

“…Mutations that disrupt pollen S (SLF) function in the Solanaceae and Plantaginaceae have yet to be found and therefore are thought to confer either SI or lethality. However, mutations that disrupt pollen S (SFB) function found in Prunus result in SC (Tao and Iezzoni, 2010;Ushijima et al, 2004;Yamane and Tao, 2009), indicating that the Prunus pollen S determinant may act to prohibit unknown mechanisms that inactivate the cytotoxic effects of the S-RNase. In other words, it is thought that multiple pollen S determinants (SLFs) would collaboratively detoxify the non-self S-RNases in the Solanaceae, while a single pollen S determinant (SFB) would release the cytotoxicity of the self S-RNase in Prunus.…”

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

“…The breakdown of self-incompatibility accompanying polyploidy in S-RNase-based GSI species of Solanaceae, and the subfamily Maloideae of Rosaceae is a result of "competitive interaction" (e.g. Golz et al, 2001;Sassa et al, 2010;Yamane and Tao, 2009) in which pollen grains containing two copies of the same pollen-S allele (homoallelic pollen) are arrested if the cognate S-RNase is present in the style, while pollen grains containing two different pollen-S alleles (heteroallelic pollen) are compatible, regardless of the S-RNase composition of the style (Chawla et al, 1997;Kao and Tsukamoto, 2004;Luu et al, 2001). Since the selfincompatibility of the genus Citrus is assumed to be GSI type (Ollitrault et al, 2007), although it is so far unclear whether the mechanism is governed by S-RNase or not, the breakdown of incompatibility by 2n pollen of 'Nishiuchi Konatsu' seems to be attributed to a system like the competitive interaction.…”