Modulation of TDZ-induced morphogenetic responses by anti-auxin TIBA in bud-bearing foliar explants of Kalanchoe pinnata

Abstract

This investigation was conducted to study the range of TDZ-induced morphogenetic responses displayed by foliar explants of Kalanchoe pinnata with or without an epiphyllous bud and to assess their possible auxin mediation by using potent anti-auxin TIBA. Each epiphyllous bud developed into a healthy plantlet when cultured in vitro without nutrient/hormonal supplements. The bud on 10 )6 M TDZ-treated leaf disc produced a compact, dwarf and rootless plantlet having achlorophyllous leaves with increased number of marginal notches. TDZ also caused a significant enlargement of the leaf disc as well as induced an organized hypertrophic growth at a specific site, with either effect being more pronounced in discs without an epiphyllous bud. Treatment with 10 )4 M TIBA completely checked the plantlet growth. In combined dispensations, the TDZ-induced responses were modified by the anti-auxin TIBA in more than one way. Whereas it caused a complete reversal of hypertrophic growth on leaf discs and partially restored pigmentation of plantlet leaves, it could not annul the leaf disc enlargement. The diverse morphogenetic modulations were tissue and response specific. A complete reversal of TDZ-induced leaf disc hypertrophy by TIBA indicated an auxin mediation, whereas a complete non-reversal of the induced leaf disc enlargement pointed to the noninvolvement of auxin, for the respective responses. The latter response could probably be manifested through cytokinin-activity of TDZ, while still others may not be interpreted exclusively through either one of the two hormonal options.

Thidiazuron-induced hypertrophic growth from foliar disks of Kalanchoe pinnata leads to visualization of a bioactive auxin gradient across the leaf plane

“…However, 100 μM TIBA, an auxin efflux inhibitor, which did not induce any of these two effects by itself, could completely reverse the latter response while not affecting the former at all. These results are in conformity with the earlier report (Jaiswal and Sawhney 2006b) and clearly show that TDZ-induced hypertrophic growth from the leaf disks was an exclusive auxin-mediated response.…”

“…As TDZ-induced hypertrophic growth was considered a consequence of polar transport/ accumulation of the pre-existing auxin under its influence (Jaiswal and Sawhney 2006b), the magnitude of response could well be taken as a reflection of the auxin level for each disk.…”

“…In a recent study, TDZ was shown to induce a significant hypertrophic growth from foliar explants of K. pinnata (Jaiswal and Sawhney 2006b). These hypertrophic growths consist of organized cells with some differentiating vascular elements and always occurred on the proximal side of the leaf disk at the vein endings.…”

Micropropagation of Cotoneaster wilsonii Nakai—a rare endemic ornamental plant

“…Thus, TDZ might be carried over from the shoot multiplication medium to inhibit rooting in PGR free medium. The inhibitory effect of TDZ has been reported in many plant species (Gray and Benton 1991;Huetteman and Preece 1993;Casanova et al 2004;Jaiswal and Sawhney 2006;Ray and Bhattacharya 2008). Auxins most frequently incorporated in the medium to induce rooting are IAA, IBA and NAA.…”

TDZ pulsing evaluation on the in vitro morphogenesis of peach palm

“…It enhances in vitro vegetative propagation in several species, both by the development of adventitious buds (Wilhelm 1999;Almeida et al 2012) and by the induction of somatic embryos (Hutchinson et al 1996;Zhang et al 2001;Almeida et al 2012). Nevertheless, in vitro usage of this cytokinin is unfavorable to shoot elongation (Gill and Ozias-Atkins 1999;Ahmad et al 2006), normal development of leaves (Nieuwkerk and Zimmerman 1986) and rooting (Hutchinson et al 1996;Jaiswal and Sahwney 2006).…”