In vitro conservation of oil palm somatic embryos for 20 years on a hormone-free culture medium: characteristics of the embryogenic cultures, derived plantlets and adult palms

Abstract

This study was conducted over a period of 20 years, to assess the problems involved in developing subcultures over a very long period, of oil palm (Elaeis guineensis Jacq.) somatic embryos which were maintained in vitro on a Murashige and Skoog mineral-based culture medium, without growth regulators. Analysis of the proliferation rate of the embryogenic cultures, along with the survivability of the regenerated plantlets after their transfer into soil and of the flowering of the derived adult palms has been conducted for cultures maintained in vitro during 1 to 20 years. From the ninth year of maintenance, the tissue quality of the somatic embryos gradually began to decline. However, after more than 20 years, 30% of the 20 clones tested still continued to proliferate satisfactorily on the same maintenance medium, keeping their multiplication potential intact. Even though a depressive effect of the age of the lines has been observed on the survival capacity of plants under natural conditions, it is noteworthy that among the clones originating from 20-year-old cultures only eight of them (40%) have exhibited the "mantled" floral abnormality. Different hypotheses concerning the origin of the disruptions observed on the in vitro cultures, plantlets and adult palms that occur over a very long period of in vitro conservation are discussed.

Long-term somatic embryogenesis in olive (Olea europaea L.): Influence on regeneration capability and quality of regenerated plants

“…Extensive experimentation about the effect of long-term maintenance by continuous proliferation on regeneration ability has been carried out in conifers species (Breton et al, 2005(Breton et al, , 2006Dunstan and Bethune, 1996;Klimaszewska et al, 2009;Konan et al, 2010;Park et al, 2011). However, deeper insight is needed in angiosperms species, such as olive, where somatic embryogenesis present differential features.…”

Histological analysis and transcription profiles on somatic embryogenesis in interspecific hybrids of <i>Elaeis guineensis × E. oleifera</i>

“…The induction of shoots on poly-embryogenic complexes was proven successful [12,13] as proposed earlier for the interspecific hybrids [45]. Cultivating poly-embryogenic complexes in medium supplemented with abscisic acid [9] before shoot induction might contribute to synchronization [46].…”

“…Cultivation in medium free of growth regulators during the stage of multiplication of the embryogenic cultures would be essential to obtain normal regenerated plantlets, when this stage is to be maintained for very long periods, as 20 years [13]. In the present work the best condition for multiplication-maturation of somatic embryos was 8 mg·l −1 2,4-D applied for a little more than a year [21].…”

“…Massive multiplication was reported late in the 1990s and in the 2000s [11][12][13]. Nevertheless, many aspects of in vitro research, including induction and maintenance of embryogenic cultures, are still poorly understood.…”

In vitro maintenance, under slow-growth conditions, of oil palm germplasm obtained by embryo rescue

“…bras., Brasília, v.50, n.5, p.426-429, maio 2015 DOI: 10.1590/S0100-204X2015000500010 -peng et al, 2012;Lédo et al, 2014;Nogueira et al, 2014). Currently, in vitro technology for the conservation of oil palm germplasm is focused almost exclusively on the technique of cryopreservation of zygotic embryos (Villa et al, 2007), somatic embryos (Konan et al, 2010), and pollen (Tandon et al, 2007). However, despite its relative effectiveness, cryopreservation requires a highly-specialized structure and labor, and it is a technique aimed at long-term conservation (Sánchez-Chiang & Jiménez, 2010).…”