Articles
NATIVE WALNUTS OF TEXAS
Article number
948_22
Pages
199 – 210
Language
English
Abstract
Three species of Juglans occur naturally in Texas.
Eastern Black walnut, J. nigra is found in eastern to central Texas. J. major, the Arizona walnut, is reported in scattered, disjunct populations from central to west Texas. J. microcarpa, the Little walnut, occurs from central to west Texas.
Hybrids between all species have been previously reported.
Collections were made from several autochthonous populations of each species, some previously undocumented, for the purpose of providing germplasm for use in the NCGR-Davis.
Samples were characterized for morphological descriptors of nuts and leaves, revealing considerable overlap between species.
DNA was extracted from each individual and evaluated using plastid microsatellite markers developed for use in the sister genus Carya. Of three loci (ccmp2, ntcp40, ntcp9), all of which show polymorphism in Carya, only one (ntcp40) was polymorphic among Texas walnuts.
Samples of J. nigra from populations in the eastern U.S. revealed additional alleles for ntcp40, but remained monomorphic at the other loci.
Samples of J. regia and J. mandshurica had unique alleles at all three plastid loci. Juglans microcarpa and J. major samples from Texas populations shared three alleles, two of which were the only alleles at the ntcp40 locus found in J. nigra from Texas.
Observations are consistent with interspecific hybridization between Texas walnuts.
Shell texture was the most convincing indication of hybridity between J. major and J. nigra. Hybrid individuals involving J. microcarpa and its sister species were suspected based on a combination of morphological and molecular characteristics.
Eastern Black walnut, J. nigra is found in eastern to central Texas. J. major, the Arizona walnut, is reported in scattered, disjunct populations from central to west Texas. J. microcarpa, the Little walnut, occurs from central to west Texas.
Hybrids between all species have been previously reported.
Collections were made from several autochthonous populations of each species, some previously undocumented, for the purpose of providing germplasm for use in the NCGR-Davis.
Samples were characterized for morphological descriptors of nuts and leaves, revealing considerable overlap between species.
DNA was extracted from each individual and evaluated using plastid microsatellite markers developed for use in the sister genus Carya. Of three loci (ccmp2, ntcp40, ntcp9), all of which show polymorphism in Carya, only one (ntcp40) was polymorphic among Texas walnuts.
Samples of J. nigra from populations in the eastern U.S. revealed additional alleles for ntcp40, but remained monomorphic at the other loci.
Samples of J. regia and J. mandshurica had unique alleles at all three plastid loci. Juglans microcarpa and J. major samples from Texas populations shared three alleles, two of which were the only alleles at the ntcp40 locus found in J. nigra from Texas.
Observations are consistent with interspecific hybridization between Texas walnuts.
Shell texture was the most convincing indication of hybridity between J. major and J. nigra. Hybrid individuals involving J. microcarpa and its sister species were suspected based on a combination of morphological and molecular characteristics.
Publication
Authors
L.J. Grauke, T.E. Thompson, M.A. Mendoza-Herrera
Keywords
Juglans, microsatellite markers, interspecific hybrids
Online Articles (34)