Rooting Of Microshoots Research Articles

Thidiazuron: a potent cytokinin for woody plant tissue culture

Thidizuron (TDZ) is among the most active cytokinin-like substances for woody plant tissue culture. It facilitates efficient micropropagation of many recalcitrant woody species. Low concentrations (<1 µM) can induce greater axillary proliferation than many other cytokinins; however, TDZ may inhibit shoot elongation. In some cases it is necessary to transfer shoots to an elongation medium containing a lower level of TDZ and/or a less active cytokinin. At concentrations higher than 1 µM, TDZ can stimulate the formation of callus, adventitious shoots or somatic embryos. Subsequent rooting of microshoots may be unaffected or slightly inhibited by prior exposure to TDZ. The main undesirable side effect of TDZ is that cultures of some species occasionally form fasciated shoots. The high cytokinin activity and positive response of woody species to TDZ have established it as among the most active cytokinins forin vitro manipulation of many woody species.

Micro- and Cutting Propagation of Silver Maple. I. Results with Adult and Juvenile Propagules

Clonal micropropagation studies with silver maple (Acer saccharinum L.) included experiments with various shoot. explant types, cytokinins, and stock plant maturation levels. These trials led to successful explant establishment, axillary shoot proliferation, rooting of microshoots, and establishment of plantlets in the greenhouse. Overall, the best cytokinin tested was the phenylurea derivative TDZ. Shoot proliferation on juvenile explants was poor with kinetin, 2iP, and BA. Only zeatin at 10 μm was comparable to TDZ. TDZ at 10 nm was optimal for both juvenile and adult nodal explants. Juvenile explants that were held in vitro for 4 months commonly had at least 60 axillary shoots that could be subculture or excised for rooting. Microshoots rooted within 2 weeks. Following rooting, silver maple plantlets could be transplanted into a growing medium and placed directly onto a greenhouse bench. Studies were also conducted on rooting stem cuttings (macropropagation). Single nodes from juvenile plants rooted under intermittent mist, regardless of auxin application; however, shoot-tip cuttings from adult trees rooted best when auxin in ethanol solution was applied. Chemical names used: N- phenyl- N' -1,2,3 -thiadiazol-5-ylurea (thidiazuron, TDZ), N- (2-furanylmethyl)-1H-purin-6-amine (kinetin), isopentenyladenine (2iP), benzyladenine (BA), (E)-2-methyl-4-(1H-purin-6-ylamino)-2-buten-1-ol (zeatin).

Micro- and Cutting Propagation of ‘Crimson Pygmy’ Barberry

Abstract Increased numbers and length of roots were produced from stem cuttings of ‘Crimson Pigmy’ barberry (Berberis thunbergii atropurpurea) treated with 3000 ppm IBA (50% ethanol/water, v/v). Two node explants from greenhouse-grown stock plants performed best if oriented vertically on woody plant medium with 5 or 10 μm BA and μm GA3. Up to 20 axillary shoots were produced from each explant in 3 months, and leaves that normally become spines grew in vitro as round green lamina with petioles. IBA did not stimulate rooting of microshoots, which are more difficult to root than cuttings. Chemical names used: 1H-indole-3-butanoic acid (IBA), N-(phenylmethyl)-1H-purin-6-amine (BA), and gibberellic acid (GA3).

Effects of Liquid Medium on Rooting and Acclimation of Regenerated Microshoots of Banana (&lt;i&gt;Musa sapientum&lt;/i&gt; L.) cv. Sagar

A regeneration protocol ensuring a high frequency rooting of micro-shoots derived from apical and axillary buds of suckers of banana cv. Sagar was achieved by using liquid medium. When the explants were cultured on MS medium supplemented with 0.5 mg/l each of BA, Kn and NAA, a large number of shoots developed. With the progression of the number of subcultures, shoot proliferation was enhanced. Addition of 10 % coconut water to the medium increased the number of shoots per culture and growth of individual shoots. Shoots rooted well within two weeks, when they were separated individually and sub-cultured in 1.0 mg/l IBA supplemented half strength MS liquid and agar-gelled medium but rooting percentage and their growth were superior in the liquid medium to agar-gelled medium. Rooted plantlets were transferred to small polythene bags containing sterile sand, soil and humus (1 : 2 : 1) and maintained with a high humidity for acclimation. Acclimation and transplantation performances were found to be superior in plants that were rooted in the liquid medium.Key words: Banana, Liquid medium, Regeneration, Acclimation, TransplantationDOI = 10.3329/ptcb.v16i1.1100Plant Tissue Cult. &amp; Biotech. 16(1): 11-18, 2006 (June)