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- Author or Editor: Mary A. Hosier x
N-phenyl-N′1,2,3-thiadiazol-5-ylurea (thidiazuron) and several substituted pyridyl phenylurea compounds have been demonstrated to stimulate in vitro meristem and shoot formation at unusually low concentrations. These compounds appear to have strong cytokinin-like effects on a wide range of species and on species that respond little to conventional cytokinins. Thidiazuron has been reported to stimulate shoot proliferation in several woody species (e.g., Acer and Malus). The addition of 0.5μm N-(2-chloro-4-pyridyl)-N′-phenylurea (CPPU) to the culture medium caused dramatic shoot number increases in hardy dedicuous azaleas (Rhododendron sp.) cultured in vitro. In petunia (Petunia ×hybrida Hort. Vilm.-Andr.) leaf test systems both thidiazuron and CPPU caused greater proliferation when used as explant dips or in the medium than similar treatments with N-(phenylmethyl)-1H-purin-6-amine (BA). Further possible applications and roles for these compounds are discussed.
Shoot proliferation of lingonberry (Vaccinium vitis-idaea ssp. minus) was achieved in vitro from shoot tips excised from 1-year-old stock plants and cultured on a low-salt medium supplemented with 2iP. Rooting was obtained without auxin application by placing microshoots in a peat-vermiculite medium in a high humidity chamber. After 6 weeks, the rooted plantlets were transplanted into a peat-lite mix, subjected to a 2-week low humidity acclimation process and subsequently acclimated in a greenhouse under 50% shade. Within 9 months, these plantlets developed a rhizomatous growth habit, in contrast to the nonrhizomatous habit of conventionally rooted cuttings. Chemical names used: N-(3-methyl-2-butenyl)-1H-purin-6-amine (2iP).
Multiple shoots of Chinese chestnut (Castanea mollissima Blume), produced in vitro from axillary buds of juvenile shoots, were successfully rooted and transplanted to the greenhouse. Benzyladenine (BA) at 0.44 μM promoted the proliferation of axillary shoots, but 4.44 μM and 44.4 μM of BA inhibited buds from sprouting and promoted callus growth. Zeatin at 4.56 μM, induced longer and more vigorous shoots than BA, but did not promote the multiplication of axillary shoots. Rooting was achieved by a 1 sec basal dip of excised microshoots in 9.8 mM or 14.8 mM indolebutyric acid (IBA) solution. The treated shoots were transferred to a plant growth regulator-free medium in flasks or to plastic flats containing sand under high humidity. Roots developed within 30 days in both rooting regimes.
Rapid clonal propagation of Alnus glutinosa was achieved in vitro using lateral buds excised from greenhouse grown, juvenile stock plants. Multiple shoot development occurred in 50% of the cultures after the first subculture (7–8 weeks after initial explanting) using a low salt, woody plant medium containing 1 μM 6-benzylaminopurine (BA). Microshoots were removed from pro-liferating tissues and rooted in a conventional potting medium under high humidity prior to establishment in the greenhouse.