Callus Initiation and Plant Regeneration from Triticale Embryos¹

Abstract

This study was conduced to determine optimal concentrations of sucrose and combinations of growth regulators required for callus initiation and plant regeneration from immature embryos of 'Councill' and other triticales (X Triticosecale Wittmack) and to make histological observations of triticale callus during differentiation and organogenesis. Immature triticale embryos were cultured on a basal medium containing the salts of Murashige and Skoog and vitamins plus selected concentrations of sucrose and different auxins or cytokinins, alone or in combination. The optimal concentration of sucrose for increasing fresh weight of callus derived from hexaploid embryos was 20 g/liter. The addition of 2, 4‐D [(2, 4 dichlorophenoxy) acetic acid] to the basal medium was superior to the addition of IAA (indoleacetic acid), kinetin (6‐furfurylaminopurine) and auxin/cytokinin combinations for both callus initiation and growth. higher concentrations of 2, 4‐D (6 mg/liter) promoted callus initiation and growth, but prevented plant regeneration on callus subsequently subcultured to a medium without growth regulators. Histological observations gave evidence of formation of active growth centers or meristemoids in callus. These subsequently led to differentiated root primordia. Our study showed that triticale embryos behaved similar to other cereals in their callus initiation and plant regeneration traits.

In vitro morphogenetic responses of mature wheat embryos to different NaCl concentrations and growth regulator treatments

“…Chin and Scott (1977) obtained satisfactory shoot induction rates from embryo callus by applying a combination of NAA (1 mg/1) and kinetin (5 mg/1). However, as indicated by the results obtained in the present study (experiments 1 and 2) and by the data reported by Sharma et al (1981) (for Triticale embryos) and Kintzios et al (1996) (for T. aestivum and T. durum embryos), this combination of growth regulators might have been less appropriate for shoot induction than the application of NAA alone.…”

“…1 Auxin applied at high concentrations during the induction and proliferation phases and carried over with calli subcultured for root and shoot induction, as previously reported for 2,4-D in Triticale (Sharma et al 1981) and wheat (Kintzios et al 1996), or; 2 The increased root induction at high auxin and NaCl concentrations. This competition between root induction and shoot induction was clearly observed in all three experiments: when root formation preceded shoot induction and roots were induced at high percentages (experiments 1 and 2) low shoot induction rates were observed.…”

“…Plant regeneration from embryo callus culture appears to be a stepwise process, consisting of callus induction, callus proliferation, organogencsis and/or somatic embryogenesis and plantlet formation (Ahloowalia 1982, Mathias et al, 1986. 2,4dichlorophenoxyacetic acid (2,4-D), at concentrations of 2-4 mg/1, is the most commonly used growth regulator for the initiation and maintenance of callus cultures from wheat embryos (Dudits et al 1975, O'Hara and Street 1978, Mac-Kinnon 1986, Mohamand and Nabors 1990, Mohamand 1993, In general, a reduction in auxin concentration results in organo-genesis and plant regeneration (root and shoot induction) succeeds after transfer of that callus either to a medium containing certain combinations of plant growth regulators or no regulators at all (Shimada et al, 1969, Sharma et al 1981, Bajaj 1986, Ovesna and Lhotova 1987, Elena and Ginzo 1988, Mohamand 1993. A low exogenous auxin application (such as napthalene-1-acetic acid (NAA) at 1 mg/1) will initiate only roots (Chin andScott 1977, Ahloowalia 1982).…”

Callus induction and plant regeneration from immature embryos of rye and triticale

“…Cytokinin-supplemented media did not induce sustained growth of callus from embryos ( Table 1). The usefulness of 2,4-D as an effective auxin for caUus initiation and growth has been demonstrated for wheat [4,11], maize [5,6], barley [1] and triticale [13]. 2,4,5-T has been found to be very effective in caUus cultures of wheat [2].…”

Genetic Engineering and Precision Editing of Triticale Genomes

“…In vitro techniques to induce direct somatic embryogenesis, secondary embryogenesis, and plant regeneration from cereals require a specific sequence of defined media, hormonal composition, and controlled growth conditions. Application of 2,4-D as an effective auxin for direct somatic embryogenesis, embryogenic callus initiation and growth have been demonstrated in triticale like in other cereals (Sharma et al 1981). Besides 2, 4-D, various other growth regulators -2, 4, 5-T and 2, 4, 5-CI 3 POP-are also shown to be suitable for initiation and maintenance of callus cultures from immature embryos in triticale though at a lesser extent (Eapen and Rao 1982).…”