Joseph C. Goffreda

Indole butyric acid induces regeneration of phenotypically normal apricot (Prunus armeniaca L.) plants from immature embryos

A prerequisite for most transformation systems is an efficient and reliable method to regenerate phenotypically normal plants. Immature embryos or cotyledons were cultured at three developmental stages (stage 1, 2 and 3, PF=3, 30–60, and 100, respectively) from two unrelated apricot genotypes, ‘Zard’ and ‘NJA82’. Explants were cultured on MS media supplemented with either BA or TDZ at four concentrations (0, 0.5, 5.0 or 20 μM) and 2,4-D at 0 or 1 μM. Stage 1 embryos cultured on MS medium without growth regulators formed embryoid-like structures. Shoot primordia induction was greatest with stage 2 cotyledons on media containing 5–20 μM TDZ and 1 μM 2,4-D, although shoot morphology was abnormal, especially with the highest level of TDZ. In another factorial experiment, stage 2 cotyledons were cultured on media containing TDZ (0, 5, 7.5, 10, 15 or 20 μM) in combination with either no auxin, 1 μM 2,4-D, 1 μM IBA, or 5 μMIBA. Regeneration percentages of 80% or more were observed on media containing 1–5 μM IBA and 5–10 μM TDZ. The medium containing 5 μM IBA and no TDZ exhibited the highest frequency of phenotypically normal plantlet regeneration.

Inheritance of isozymes in peach x Prunus kansuensis and peach x Prunus davidiana hybrids

SummaryIsozyme variation and inheritance were investigated with starch gel electrophoresis in peach (Prunus persica L. Batsch) x P. kansuensis Rehd. and peach x P. davidiana (Carr.) Franch. interspecific hybrids. Of five enzyme systems surveyed for polymorphism, four systems were identified as polymorphic [isocitrate dehydrogenase (IDH, EC 1.1.1.41), phosphoglucomutase (PGM, EC 2.7.5.1), aspartate aminotransferase (AAT, EC 2.6.1.1), and 6 phosphogluconate dehydrogenase (PGD, EC 1.1.1.44)] and may be useful as genetic markers in future cultivar and rootstock development. Analysis of progenies segregating for pairs of loci suggests a possible linkage between the loci coding for Aat-1 and Pgd-2. Independent assortment was observed for isozyme loci Idh/Pgm-2, Idh/Aat-1, Idh/Pgd-2, Pgm-2/Aat-1, Pgm-2/Pgd-2, and Aat-2/Aat-1. The red leaf locus, Gr, assorted independently of the isozyme loci: Idh, Pgm-2, Aat-1, and Pgd-2.