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Self-incompatibility (SI) is a mechanism that many flowering plants employ to prevent fertilisation by self- and self-like pollen ensuring heterozygosity and hybrid vigour. Although a number of single locus mechanisms have been characterised in detail, no multi-locus systems have been fully elucidated. Historically, examples of the genetic analysis of multi-locus SI, to make analysis tractable, are either made on the progeny of bi-parental crosses, where the number of alleles at each locus is restricted, or on crosses prepared in such a way that only one of the SI loci segregates. Perennial ryegrass (Lolium perenne L.) possesses a well-documented two locus (S and Z) gametophytic incompatibility system. A more universal, realistic proof of principle study was conducted in a perennial ryegrass population in which allelic and non-allelic diversity was not artificially restricted. A complex pattern of pollinations from a diallel cross was revealed which could not possibly be interpreted easily per se, even with an already established genetic model. Instead, pollination scores were distilled into principal component scores described as Compatibility Components (CC1-CC3). These were then subjected to a conventional genome-wide association analysis. CC1 associated with markers on linkage groups (LGs) 1, 2, 3, and 6, CC2 exclusively with markers in a genomic region on LG 2, and CC3 with markers on LG 1. BLAST alignment with the Brachypodium physical map revealed highly significantly associated markers with peak associations with genes adjacent and four genes away from the chromosomal locations of candidate SI genes, S- and Z-DUF247, respectively. Further significant associations were found in a Brachypodium distachyon chromosome 3 region, having shared synteny with Lolium LG 1, suggesting further SI loci linked to S or extensive micro-re-arrangement of the genome between B. distachyon and L. perenne. Significant associations with gene sequences aligning with marker sequences on Lolium LGs 3 and 6 were also identified. We therefore demonstrate the power of a novel association genetics approach to identify the genes controlling multi-locus gametophytic SI systems and to identify novel loci potentially involved in already established SI systems. [ABSTRACT FROM AUTHOR]

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Sphorophytic pollen-stigma incompatibility is a characteristic of the genus Corylus. Incompatibility alleles expressed in the pollen of Turkish hazelnut cultivars were identified. Cultivars were selected from the field collection at Giresun, and were used as the pollen parents. Tester plants, whose S-alleles were known, were located in Ankara and Corvallis. Compatible crosses produced masses of long and parallel tubes while incompatible crosses produced very short tubes that often curved or ended with a pronounced bulb. The incompatibility alleles S2, S5, S8, S10, S12, S21 and S24 were identified in the pollen of Turkish cultivars. Pollen of Palaz and Yuvarlak Badem expresses S2, pollen of Fosa, Mincane and Sivri expresses S8, pollen of Kan, Cavcava, Acý and Kargalak expresses S10, pollen of Ýncekara, Kalýnkara and Uzunmusa expresses S21, pollen of Yassý Badem expresses S5, pollen of Tombul expresses S12 and pollen of Çakýldak expresses S24. [ABSTRACT FROM AUTHOR]