CHARACTERIZATION OF AUSTRALIAN ALMOND CULTIVARS AND COMPARISON WITH CALIFORNIAN CULTIVARS BY ISOZYME POLYMORPHISM

Australian-derived almond cvv. Baxendale, Bruce, Chellaston, IXL Seedl ing, Johnston's Prolific, Keane's Seedling, Pethick's Wonder, Somerton , and White Brandis were identified by means of isozyme polymorphisms at 8 genetic loci: AAT-1, GPI-2, LAP-1, PGM-1, PGM-2, IDH, G6PD, and S KDH. The same genetic markers were used to compare Australian almond c ultivars with commonly grown Californian cvv. Carmel, Davey, Drake, Fr itz, Mission, Ne Plus Ultra, Nonpareil, Peerless, Price, and Thompson. The assignment of alleles at the various loci was aided by an examina tion of the inheritance of these markers by crossing Nonpareil with po llen from 17 Australian and Californian cultivars. This demonstrated, for the first time, null genes in Price at LAP-1 and in Drake at AAT-1 . The Australian cultivars differed from the Californian at several lo ci. These differences arise from the separate development in Australia of almond cultivars from what is believed to be largely Spanish 'Jord an' types, before a shift to larger irrigated orchards using Californi an methods and Californian-Australian cultivars.