Inheritance of Venation Pattern in Prunus ferganensis × persica Hybrids

Prunus ferganensis (Kost. & Riab) Kov. & Kost, is closely related to cultivated peach, P. persica (L.) Batsch, but is distinguished by very long, unbranched leaf veins which turn and run parallel to the leaf margin at the edge of the leaf. Also, the pits have longitudinal grooves. Otherwise the tree and fruit of this species (or sub-species) resemble those of our familiar commercial peach. P. ferganensis is common in the dry Ferghana and Zeravshan Valleys in central Asia (now Tajikistan, Kyrgyzstan and Uzbekistan). In this region local cultivars of P. ferganensis are widely grown for fruit. Several old accessions of P. ferganensis such as Plant Introduction 102705 (‘Khodjent Kostokos’) are in the United States and a few additional accessions have been brought in as seed in recent years. Fruit quality is edible but not of commercial standard, particularly in terms of fruit firmness, quality and skin color. The species has been little studied in the US. Hybrids of P. ferganensis (primarily nectarine PI 102705) with commercial and experimental peaches have been produced, and segregating F2 populations obtained. These populations were evaluated for fruit, seed and tree characters. The distinct leaf-vein character segregates in a ratio of 3 normal vein:1 long vein suggesting it is controlled by a single recessive gene. All of the long-veined progeny that fruited also had the grooves on the pit, in contrast to the normal seed of normalveined seedlings. The preeminence of this species in its region of origin, where it is frequently cultivated, suggests the leaf morphology may be advantageous, perhaps in terms of water relations. If the long-vein leaf type were found to be associated with superior water usage or photosynthetic characteristics, it would be relatively easy to backcross it into commercial type fruit.