Determining the specific status of the Iberian sturgeons by means genetic analyses of old specimens

To clarify the species status of sturgeon from rivers of the Iberian Peninsula, eight molecular markers (4 nuclear and 4 mitochondrial) have been analysed in different specimens from historical museum samples and prehistoric samples from archaeological sites. These analyses indicate that one of these specimens (UGP captured in the Guadalquivir River in the 19th century) is A. sturio, based on all the eight molecular markers, four of them used from the first time in this study. In previous analyses based on 5 genetic markers, our group assigned two specimens captured in this river in the 1970-80s (EBD8173 and EBD8401) to the species A. naccarii, suggesting the presence of this species in the Iberian Peninsula. In this work, this conclusion is drawn after successfully obtaining a mitochondrial marker in a very old scute from a prehistoric site (Acinipo, about 1500 BC, from the Guadalquivir River basin). On the other hand, in the specimen EBD8174 captured in the Guadalquivir in 1975, we have obtained two new mitochondrial markers confirming that it can be considered A. sturio for all the mitochondrial markers, but nuclear ones identify it as A. naccarii. Finally, two very old samples (Nerja E-VI and Nerja N/62-63) were not successfully characterized by any molecular markers. Some aspects and consequences of our results are discussed, such as the origin of the “mosaic” specimen EBD8174 and, above all, the native status of A. naccarii in historic and prehistoric times in the southern Iberian Peninsula.

Pistachio genomes provide insights into nut tree domestication and ZW sex chromosome evolution

Pistachio is a nut crop domesticated in the Fertile Crescent and a dioecious species with ZW sex chromosomes.We sequenced the genomes of Pistacia vera cultivar(cv.)Siirt,the female parent,and P.vera cv.Bagyolu,the male parent.Two chromosome-level reference genomes of pistachio were generated,and Z and W chromosomes were assembled.The ZW chromosomes originated from an autosome following the first inversion,which occurred approximately 8.18 Mya.Three inversion events in the W chromosome led to the formation of a 12.7-Mb(22.8%of the W chromosome)non-recombining region.These W-specific sequences contain several genes of interest that may have played a pivotal role in sex determination and contributed to the initiation and evolution of a ZW sex chromosome system in pistachio.The W-specific genes,including defA,defA-like,DYT1,two PTEN1,and two tandem duplications of six VPS13A paralogs,are strong candidates for sex determination or differentiation.Demographic history analysis of resequenced genomes suggest that cultivated pistachio underwent severe domestication bottlenecks approximately 7640 years ago,dating the domestication event close to the archeological record of pistachio domestication in Iran.We identified 390,211,and 290 potential selective sweeps in 3 cultivar subgroups that underlie agronomic traits such as nut development and quality,grafting success,flowering time shift,and drought tolerance.These findings have improved our understanding of the genomic basis of sex determination/differentiation and horticulturally important traits and will accelerate the improvement of pistachio cultivars and rootstocks.