GUS expression in blueberry (Vaccinium spp.): factors influencing Agrobacterium-mediated gene transfer efficiency.

Several factors were investigated for their influence on the transfer of an intron-containing β-glucuronidase (GUS) gene into blueberry (Vaccinium spp.) leaf explants during the early stages of Agrobacterium-mediated gene transfer, including days of cocultivation, strain of Agrobacterium tumefaciens, explant age and genotype. The number of GUS-expressing leaf zones and calli were counted immediately and 2 weeks after cocultivation, respectively, to evaluate the gene transfer process.

RAPD analysis of somaclonal variants derived from embryo callus cultures of peach.

Peach [Prunus persica (L.) Batsch] regenerants from cv 'Sunhigh' embryo no. 156, regenerants obtained from cv 'Redhaven' embryo no.

Optimal Levels of Meloidogyne incognita Inoculum for Infection of Tomato and Peach in Vitro.

Penetration of second-stage juveniles (J2) of Meloidogyne incognita into tomato root explants and in vitro propagated peach plantlet roots were compared. Five inoculum levels were used: 25, 50, 75, 100, and 200 J2 for tomato; and 50, 100, 200, 500, and 1,000J2 for peach. The greatest root penetration into tomato was 30% at the 75 J2 level, but the maximum penetration into peach roots was only 8% at the 200 J2 level.

Response of Peach Scion Cultivars and Rootstocks to Meloidogyne incognitain Vitro and in Microplots.

The response of the peach scion cultivars, Jerseyqueen, Redhaven, Compact Redhaven, and Rio Oso Gem and rootstocks 'Lovely and 'Nemaguard' to inoculation with Meloidogyne incognita was compared in vitro and in microplots. One or more parameters monitored in vitro correlated with at least one parameter monitored in microplots, 4 years after tree planting (1989). A range of responses was observed from highlysusceptible in Lovell to resistant in Nemaguard.

Selection of peach cells for insensitivity to culture filtrates of Xanthomonas campestris pv. pruni and regeneration of resistant plants.

Individual callus cultures were initiated from 400 immature embryos of bacterial leaf spot-susceptible 'Sunhigh' peach. Each was subjected to several selection cycles of a toxic culture filtrate produced by Xanthomonas campestris pv. pruni, the causal agent of leaf spot of peach.

Regeneration of peach plants from callus derived from immature embryos.

Peach plants were repeatedly regenerated from immature embryos but not from callus derived from mature embryos. A white, nodular, highly regenerative callus was obtained when friable, primary callus from immature embryos was transferred from medium containing 4.5 μM 2,4-dichlorophenoxyacetic acid and 0.