Microsatellites in Carya

The genus Carya consists of 17 species worldwide, divided into 3 sections (Carya, the “true” hickories; Apocarya, the pecan hickories; and Sinocarya, the Asian hickories). The focus of international horticultural attention has traditionally been on pecan (Carya illinoinensis), the most widely grown species internationally.  All members of section Apocarya are diploid and hybridize frequently with pecan, providing an avenue for introgression of genes between sympatric populations distributed across southeastern United States, and into Mexico. Section Carya includes both diploid and tetraploid species, with abundant hybrid combinations described based on phenotypic patterns. Section Sinocarya, the Asian Carya species, are poorly represented in world germplasm collections, but are noteworthy both for their distinctive morphology as a group and for their limited, isolated distributions as species.  The most valuable horticultural member of that section, Carya cathayensis, has been reported to exhibit nucellar embryony and to hybridize with pecan. Nuclear and plastid microsatellites have been useful in distinguishing sections, species, populations and individuals.  They provide evidence for hybridity between species, and can confirm heredity within crosses. As more sophisticated methods of genomic evaluation are cooperatively developed for use in pecan breeding and selection, their use will be supplemented and informed by the lessons provided by microsatellite markers, as interpreted across broad germplasm collections.