Plant Regeneration from Somatic Embryogenic Suspension Cultures of Date Palm

Abstract

Somatic embryogenesis is one of the most important technologies for plant regeneration of elite date palm cultivars. Recently, considerable progress has been made in the development and optimization of this technique from embryogenic cell suspension cultures. This chapter describes a procedure for the rapid development of a large number of somatic embryos from embryogenic cell suspension cultures. An efficient plant regeneration protocol via somatic embryogenesis from cell suspension cultures starting with shoot-tip explants to plantlet acclimatization also is fully described. Low concentrations of 6-benzylaminopurine (BAP) to 0.3 mg/L and high rate of subcultures each 7 days lead to improve the establishment and multiplication of somatic embryos in suspension cultures by limiting oxidative browning, associated with high total phenols and peroxidase activities. The detailed morphological observations have revealed the cells destined to become somatic embryos. Activated charcoal (AC) at 0.15 g/L has a positive effect on growth rate of somatic embryos by reducing tissue and medium browning, phenolics, and peroxidase activity.

Signaling Overview of Plant Somatic Embryogenesis

“…The use of 2, 4-dichloroacetic acid (2, 4-D) has an essential role in the induction of SE and the initial stages of development of the somatic embryos (Nic-Can and Loyola-Vargas, 2016). For example, the productivity for embryogenic date palm crops increased 20 times by adding a low concentration of 2, 4-D (Abohatem et al, 2017). The use of auxins modified their endogenous metabolism in a significant way; for example, in carrots, the use of 2, 4-D in the culture medium induces an embryogenic response that is associated with the increase of the endogenous levels of indole-3-acetic acid (IAA) (Michalczuk et al, 1992).…”

Role of darkness in the germination process and conversion of direct somatic embryos into plantlets: Micropropagation protocol enhancement study of date palm.

“…The explants from shoot tip were cultured on a callogenesis induction medium as described by our previous research (Abohatem et al 2011 andAbohatem et al 2017), which contained Murashige and Skoog (MS) salt (Murashige and Skoog, 1962), and Fossard vitamins (De Fossar, et al 1974) supplemented with 30 g/l sucrose, 150 mg/l activated charcoal, 7 g/l agar, 5 mg/l of 6benzylaminopurine (BAP) and 5mg/l of dichlorophenoxyacetic acid (2,4-D). For direct somatic embryo induction, the rst direct somatic embryo formed was selected and transferred to a medium containing 0.5 mg/l of BAP and 0.1 mg/l of 2,4-D (El Hadrami and Baaziz 1995; Abohatem et al 2011).…”

“…The cultures were incubated at 25 ± 2 •C in the dark and subcultured to fresh medium every 5 weeks. (Abohatem et al, 2017) Multiplication of direct somatic embryos Multiplication of direct somatic embryos is conducted on MS medium containing 0.5 mg/l of BAP and 0.1 mg/l of 2,4-D (Abohatem et al 2011). To test the effect of light and darkness on the multiplication of direct somatic embryos per explant two sets of explant masses were placed, one set in the light (16 h photoperiod) and one set in darkness continuous for the entire two subcultures' multiplication periods.…”

“…The direct somatic embryos were picked and transferred to the germination medium. The germination medium was MS medium supplemented with 0.1 mg/l naphthalenacetic acid (NAA) and 0.15 g /l activated charcoal (Abohatem et al, 2017) To test the effect of light and darkness on germination of direct somatic embryos and conversion into plantlets, somatic embryos were placed in three different light conditions treatments (16 h photoperiod, darkness continuous and darkness for three weeks followed by 16 h photoperiod) during the period of germination of somatic embryos and conversion into plantlets.…”

PROLIFERATION OF OIL PALM (Elaeis guineensis Jacq.) EMBRYOGENIC CALLUS WITH REPEATED SUBCULTURES IN LIQUID MEDIUM

“…One method that can be applied is a method using liquid medium by means of suspension culture. The use of liquid medium in plant propagation has been widely applied to various plants, such as sugarcane (Minarsih et al 2013), ginseng (Kochan et al 2019), Bentula pendula (Hajati et al 2016, dates (Abohatem et al 2017, Naik et al 2018), Sago (Riyadi et al 2016), Plumbago (Beigmohamadi et al 2019) and oil palm (Naranjo et al 2016, Wan Nur Syuhada et al 2016, Naik et al 2017, Monteiro et al 2018). The use of liquid medium is combined with a quick immersion technique using a RITA container, shaking techniques using shaker (suspension culture) or by aeration technique in a bioreactor container.…”