Characterization of 11 juglandaceae genotypes based on morphology, cpDNA, and RAPD

The interspecific and intergeneric relationships of eight species of Juglans (walnuts) and three other members of Juglandaceae were investigated. The following species were included: the American J. australis Griseb., J. neotropica Diels., J. olanchana Standl. et L.O. Williams, J. nigra L., and Carya illinoensis (Wang.) K. Koch.; two Juglans from South China, namely, J. sigillata Dode and an unidentified J. sp; an Engelhardia also from China and the Asian J. ailantifolia Carr., Pterocarya stenoptera var. tonkinensis Franchet and the Eurasian J. regia L. Cladistic analysis of 27 multistate morphological characters showed that the juvenile J. ailantifolia possessed similar physical traits to that of the juvenile American Juglans species. The chloroplast DNA in the trnL-trnF region indicated a close relationship between Juglans species. Pterocarya put the root of the cpDNA network among the American species. RAPD analysis was performed using eight primers. A total of 138 fragments were generated but only 78 clearly defined bands were used in the analysis. All the DNA data grouped the tropical/subtropical American Juglans with J. nigra, and the two new Asian species with J. ailantifolia and J. regia. The American species were closely related, more so than their Asian counter parts. The closeness of the investigated species predicts interspecific graft compatibility not only within the Asian and American groups, but also between them.