Pistacia vera - EUFORGEN European forest genetic resources programme

Genetic summary

Genetic diversity and variation

Research on the genetics of cultivated pistachio has focused on Iran, one of the species’ primary centres of origin and diversity, where high levels of polymorphism, genetic diversity, and heterozygosity have been recorded (Khadivi, Esmaeili, and Mardani, 2018; Pourian et al., 2019). However, some research has found evidence of genetic erosion in Iranian cultivated populations due to over-selection and reduced wild gene flow (Pourian et al., 2019).

Studies on European populations are more limited. Despite domestication and selective breeding, European pistachio cultivars maintain high genetic diversity because of their introduction from multiple genetic centres and local adaptation to Mediterranean conditions (Zeng et al., 2019; Karcı et al., 2022). The species’ dioecious mating system promotes genetic recombination and contributes to its high heterozygosity (Ziya Motalebipour et al., 2016).

Genetic distribution and clustering

Genetic studies show that pistachio has clear clustering patterns linked to geographic origin and breeding history. In Iran, cultivars are grouped into two to four major clusters, reflecting significant genetic differentiation among local varieties (Khadivi, Esmaeili, and Mardani, 2018; Pourian et al., 2019).

In the Mediterranean pistachio cultivars form distinct clusters related to their origins, although some genetic mixing exists due to centuries of cultivation and trade (Karcı et al., 2022). Wild populations often form separate clusters from cultivated populations, indicating strong genetic distinctiveness (Ziya Motalebipour et al., 2016; Pourian et al., 2019). Most genetic research focuses on cultivars rather than wild populations, making it challenging to fully separate natural genetic structure from the effects of domestication and human activity.

Gene flow

Pistachio is a wind-pollinated species, with seeds that are animal dispersed. It is dioecious, meaning male and female flowers occur on separate trees (Karcı et al., 2022). This promotes high gene flow between populations and cultivars, enhancing genetic mixing and maintaining relatively high heterozygosity despite domestication. Pistachio is diploid, with a haploid chromosome number, providing a stable genetic basis for hybridization and breeding. Gene flow is heavily influenced by human-mediated propagation through grafting and cultivar exchange across regions.

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Further relevant genetic traits

Cultivation and human intervention

Pistacia vera is the only cultivated species within the Pistacia genus, which includes at least 11 species (Karcı et al., 2022). It has been cultivated for over 3 000–4 000 years in Iran and was introduced into the Mediterranean region and Europe by the Romans (Pourian et al., 2019). Iran and Türkiye are currently major genetic and production centres, with high levels of Pistacia diversity and valuable germplasm for improvement and conservation programmes (Ziya Motalebipour et al., 2016; Khadivi, Esmaeili, and Mardani, 2018). Human intervention has selected for traits such as larger seeds, fruit yield, and growth form, shaping modern cultivars (Zeng et al., 2019). Despite domestication, pistachio cultivars retain high phenotypic and genetic variation, partly due to the tree’s dioecious and wind-pollinated nature (Karcı et al., 2022).

Wild Pistacia species are used as rootstocks and remain key sources of genes for resistance to pests, drought, cold, and salinity (Pourian et al., 2019). Although genetic admixture among wild Pistacia species occurs, introgression into pistachio is rare, suggesting a distinct genetic identity maintained under domestication (Zeng et al., 2019).

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Genetic conservation

Threats

Pistachio genetic diversity is threatened by genetic erosion linked to the widespread use of commercial cultivars, which reduces variability in traditional and wild gene pools (Pourian et al., 2019). Environmental pressures such as climate change and an escalating water crisis pose serious risks to the long-term survival of wild and cultivated populations in Iran, a major centre of diversity (Pourian et al., 2019). Moreover, tracing original genetic structure of pistachio and distribution patterns is complex due to the species’ frequent translocation and cultivation across regions. While genetics are well-studied, most research focuses on commercial breeding value and productivity rather than on conservation-oriented management (Khadivi, Esmaeili, and Mardani, 2018).

Management

Conservation of pistachio genetic diversity requires integrating genetic hotspot protection, particularly in Iran and adjacent regions, into global and European strategies (Khadivi, Esmaeili, and Mardani, 2018). Developing in situ and ex situ conservation programmes and maintaining gene banks of wild and cultivated germplasm are essential to safeguard diversity against environmental and anthropogenic threats. Expanding genetic studies across non-commercial populations could better inform sustainable management and breeding programmes, ensuring both resilience and long-term productivity of the species.

The bibliographic review was conducted by James Chaplin of the EUFORGEN Secretariat in August 2025.

Pistacia vera
Pistachio

Environmental zones

Genetic summary

Genetic diversity and variation

Genetic distribution and clustering

Gene flow

Further relevant genetic traits

Cultivation and human intervention

Genetic conservation

Threats

Management

Further reading

References

Pistacia veraPistachio

Environmental zones

Genetic summary

Genetic diversity and variation

Genetic distribution and clustering

Gene flow

Further relevant genetic traits

Cultivation and human intervention

Genetic conservation

Threats

Management

Further reading

References

Pistacia vera
Pistachio