Pistachio (Pistacia spp.) breeding

Abstract

The genus Pistacia L. consists of 11 or more tree and shrub species belonging to the Anacardiaceae family. Pistacia vera L. is the only commercially-important species within this genus with nuts large enough to be consumed. The center of diversity of P. vera is northern Iran, southern Turkmenistan and parts of Afghanistan. Botanically, pistachio fruits are semidry drupes composed of a fleshy exocarp and mesocarp (pericarp or hull), and a hard endocarp (shell) containing the edible kernel. Pistachio is a wind pollinated dioecious tree with apetalous pistillate and staminate inflorescences on separate female and male trees. Currently pistachio cultivation is expanding in Iran, the USA, Turkey, Greece, Italy, Spain, China, Tunisia and many other countries. However, its commercial production has been affected by the undesired physiological characteristics of alternate bearing, shell indehiscence, blank nuts and susceptibility to abiotic stresses, including drought and salinity, and fungal foliar and root diseases. Genetic improvement of these characteristics should be a factor in future breeding attempts to produce superior pistachio cultivars. This chapter describes the advances in traditional and molecular breeding of pistachio cultivars. The traditional breeding and hybridization programs discussed are focused on new female and male cultivars, and rootstocks, introduced through pistachio genomics and breeding programs. The discussion of germplasm biodiversity and molecular breeding summarizes the current knowledge of intra- and inter-specific genetic diversity, cytogenetic evaluations, and marker-assisted selection in the genus Pistacia. The current knowledge of pistachio genetic engineering including micropropagation, regeneration systems, somaclonal variation and genetic stability, in vitro conservation and cryopreservation, and genetic transformation studies are also discussed.