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  • Author or Editor: John F. Hubstenberger x
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Abstract

The procedures for micropropagation and plant regeneration from callus were developed for Allium fistulosum L., A. altaicum Pall., A. galanthum Kar. & Kir., A. roylei Stearn, and selected progeny of interspecific crosses of A. cepa × fistulosum, A. cepa × galanthum and A. cepa × oschaninii O. Fedtsch. Each of the genotypes exhibited shoot multiplication in micropropagation systems, and most regenerated plants from callus. The results demonstrate the general applicability of the picloram-based tissue culture model for the genus Allium. Chemical names used: 4-amino-3,5,6-tri-chloro-2-pyridinecarboxylic acid (picloram).

Open Access

Callus cultures were established from intraspecific lines of Allium cepa L., interspecific F1 progeny of A. cepa crossed to A. fistulosum L. and to A. galanthum L., advanced generations of A. fistulosum x A. cepa backcrossed to A. cepa, and lines of A. fistulosum and A. galanthum. These genotypes had been identified as susceptible, resistant, or partially resistant tester lines based on prior seedling and field nursery screenings using the pink-root pathogen Pyrenochaeta terrestris (Hansen) Gorenz, Walker and Larson. Tester line calli were challenged in vitro with culture filtrates of the fungal pathogen and were assessed by visible damage ratings expressed as the percentage of pigmentation in response to the filtrate. The degrees of callus sensitivity to the filtrate observed in vitro corresponded well with the in vivo tester line classifications. These results eliminated the possible confounding influence of using various species of Allium for in vitro screening. Our results indicated the suitability of the in vitro screening approach for the possible identification of useful segregants or somaclonal variants possessing pink-root resistance. However, in vivo pathogenicity may involve mechanisms in addition to sensitivity to the putative toxins present in the filtrate.

Free access

Micropropagation of 11 rare or endangered cacti species belonging to the subtribe Cactinae was achieved by rooting of proliferated axillary shoots. Shoot tip explants were obtained from seedlings of Escobaria missouriensis D.R. Hunt, E. robbinsorum (Earle) D.R. Hunt, Sclerocactus spinosior (Engelm.) Woodruff & L. Benson, and Toumeya papyracantha (Engelm.) Br. & Rose, and from mature plants of Mammillaria wrightii Engelm., Pediocactus bradyi L. Benson, P. despainii Welsh & Goodrich, P. knowltonii L. Benson, P. paradinei B.W. Benson, P. winkleri Heil, and S. mesae-verdae (Boissevain) L. Benson. Three or four species were used in each of a series of experiments investigating the effects of basal media and auxin and cytokinin types and concentrations on axillary shoot proliferation. Low or no auxin but moderate to high cytokinin concentrations were required for axillary shoot production. All species rooted spontaneously on hormone-free media; however, several species rooted better on media containing auxin. All species were re-established in the greenhouse.

Free access