Sexual incompatibility in Rosaceae fruit tree species: molecular interactions and evolutionary dynamics

Abstract

Fruit crops have a growing economic importance worldwide and molecular genetics might be useful in solving many problems that arise during commercial production. One of the fields that have attracted intense attention is the molecular basis of self-incompatibility that may result in low fruit set. In tree fruits of the Rosaceae family, the incompatibility reactions take place between the pistil S-ribonuclease (S-RNase) and the pollen-expressed S-haplotype specific F-box (SFB) proteins. In most cases, the loss of self-incompatibility was associated with mutations in the S-RNase or SFB genes. A total of 27 non-functional S-haplotypes have been identified and characterized, most (24) of which emerged as a consequence of natural mutations. In the Prunoideae, most haplotypes are pollen-part mutants (50 %), while 8 are stylar-part mutants (36 %), one haplotype shows both pollen-and stylar-part mutations, and molecular changes for two haplotypes still have not been clarified. In contrast, non-functional natural haplotypes in the Maloideae are all stylar-part mutants. The analysis of such mutants may shed light on underlying molecular mechanisms as was the case with the establishment of the general inhibitor model that describes interactions between pollen and pistil S-proteins. However, several other molecules were supposed to contribute to the molecular interactions, at least in Solanaceae, a family with a similar self-incompatibility system. This review also endeavours to delineate the evolutionary implications of the S-locus mutations and collect limited data on non-S-locus molecular interactions and signaling events after self-and cross-pollination of fruit tree species.

Self-(in)compatibility in apricot germplasm is controlled by two major loci, S and M

“…area c Country of origin d Pedigree e SI/SC e Blooming time e 1AlbaCAPAWEItalyUnknown?Mid f 2ASP a FMWESpain (V)Unknown (isolated tree) [25]?Mid f 3AuroraCAPANAUSARR17–62 × NJA-13 [26]SI [73]Mid [74]4BebecouMAGRAMASE/NAfGreeceUnknown [41]SC [73]Mid-early [41]5BergeronMAGRAMAWEFranceUnknown [41]SC [73]Mid-late [41, 47]6BudapestSt. Istvan UEEHungary‘Nancy’ × (‘Acme’, ‘Hungarian Best’, ‘Kései Rózsa’) [16]SC [16]Mid-late [75]7BúlidaMAGRAMASE/NAfSpain (M)Unknown [41]SC [73]Mid [41]8CaninoIVIAWESpain (V)Unknown [41]SC [73]Mid [41]9Canino 9–7IVIAWESpain (V)Clonal selection from Canino [27]?Mid [27]10Canino 14–4IVIAWESpain (V)Clonal selection from Canino [27]?Mid [27]11Canino 14–6IVIAWESpain (V)Clonal selection from Canino [27]?Mid [27]12CastlebriteCEBAS...…”

“…However, different ‘degrees’ of SC have been detected in this genus ranging from sweet cherry, almost strictly self-incompatible (with a few exceptions), or apricot, mainly self-incompatible (SC is restricted to European cultivars), to complete SC in peach [15]. SC is mostly related to mutations in the S -locus genes and mutations affecting both S - RNases and SFBs have been detected in many Prunus species [13, 16]. In apricot ( Prunus armeniaca L.) the S C -allele known to confer SC has been well characterized showing that a 358 bp insertion in the SFB gene leads to a putative truncated protein lacking the two essential 3′-hypervariable domains HVa and HVb [17].…”

Self-(in)compatibility genotypes of Moroccan apricots indicate differences and similarities in the crop history of European and North African apricot germplasm

“…However, most European cultivars are self-compatible [24] and only S C and S 2 -alleles were detected in many cultivars, since S 8 , S 9 , S 19 and S 20 were detected only in the Hungarian cultivars of Turkish origin and their presence must be due to a secondary and more recent introduction from Turkey. This indicates that human selection might have had an immense contribution to the evolution and dissemination of the self-compatible phenotypes in countries north of the Mediterranean sea [43]. …”

Ferilization biology and pomological properties of newlyintroduced sweet cherry (Prunus avium L.) cultivars

“…Hegedüs et al (2012) navode da je suština inkompatibilne reakcije kod vrsta familije Rosaceae u dezorganizaciji polenove cevčice, koja je vezana za izmenjenu ulogu proteina stubića u inkompatibilnim, u odnosu na kompatibilne kombinacije oprašivanja.…”

“…Hegedüs et al (2012) navode da se suština inkompatibilne reakcije kod vrsta familije Rosaceae zapravo svodi na dezorganizaciju polenove cevčice. Isti autori navode da identifikacija i odreĎivanje biološke uloge proteina stubića, za koje je do sada utvrĎeno da se ponašaju različito u slučajevima kompatibilnih i inkompatibilnih kombinacija oprašivanja, predstavljaju ključ za definisanje molekularnog mehanizma interakcije polen-stubić.…”