Proliferation and germination of somatic embryos from embryogenic suspension cultures in Ph?nix dactylifera

Abstract

The present study demonstrates a procedure for the rapid development of a high number of somatic embryos from embryogenic suspension culture. This method might be efficient for mass propagation of Phoenix dactylifera L. Embryogenic callus placed in liquid medium with 10 )5 M ABA yielded an average 72 embryos per 100 ml of culture medium within 2 months, while those placed on solid medium yielded an average of 33, 20 and 16 embryos per 100 ml of culture medium respectively for 10 )7 , 10 )6 and 10 )5 M ABA after 4 months. The combination of 2,4-DI D Ichlorophenoxyacetic acid (2,4-D D ) (4.5 · 10 )7 M), glutamine (6.7 · 10 )4 M), and ABA (10 )5 M) (L8 liquid medium) showed a beneficial effect on somatic embryos production compared to 2,4-D D and glutamine alone, while this combination significantly ( p < 0.05) increased the accumulation of storage proteins (144 and 138 mg g )1 DW respectively for Jihel and Bousthami noir cultivars) in somatic embryos. The somatic embryos which underwent maturation on medium containing only 4.5 · 10 )7 M 2,4-D D and 10 )5 M ABA (L6 liquid medium) accumulated more sugars (292 and 265 mg g )1 DW respectively for Jihel and Bousthami noir) than those matured on any other liquid medium. Histological studies revealed that somatic embryos (developed in L6 and L8 liquid media) accumulated less reserve compounds (proteins and sugars) than zygotic embryos. The addition of activated charcoal (0.25 and 0.5 g l )1 ) and phytagel Ò (2.5 g l )1 ) to the germination medium may be useful for enhancing the germination of Phoenix dactylifera somatic embryos.Abbreviations: ABA -abscisic acid; BAP -benzylamino-purine; BSTN -bousthami noir cultivar; 2,4-D D -2,4-dichlorophenoxyacetic acid; Glu -glutamine; JHL -Jihel cultivar; MS -Murashige and Skoog (1962) medium; FW -fresh weight; PAS -periodic acid-shiff; NBB -naphthol black blue

A comparative study between solid and liquid cultures relative to callus growth<br>and somatic embryo formation in date palm (Phoenix dactylifera L.) cv. Zaghlool

“…The somatic embryos were formed within 3-6 weeks after inoculation in the liquid media (Figures 5b, 7b) while they were formed in 12-18 weeks on solid medium (Ibraheem et al, 2010). Similar to our results Zouine et al (2005) reported that the initiation of somatic embryos in suspension culture within 2 months, while on solid medium somatic embryos were formed after 4 months. Recently, AlKhayri (2012) found that cell suspensions accelerated significantly the appearance of somatic embryos in date palm cv.…”

“…Khalas suspension cultures after adding BAP at 1 mg l -1 to the medium enriched with 2,4-D. Adding BAP to date palm suspension cultures was also reported by Zouine et al (2005) and Zouine and El Hadrami (2007). For other species, Yamamoto and Yamada (1986) reported that the hormonal combination of NAA and BA was the most suitable for cell suspension culture for snakeroot (Rauwolfia serpentine).…”

“…Deglet Nour (Fki et al, 2003), cvs. Bousthami noir and Jihel (Zouine et al, 2005;Zouine and ElHadrami, 2007) and cv. Khalas (Gadalla, 2007).…”

“…Cell suspensions cultures were used either for callus growth (Al-Khayri, 2012) or for somatic embryo formation (Fki et al, 2003;Zouine et al, 2005). The productivity of embryogenic cell suspension cultures increased 20-fold (from 10 to 200 embryos per month per 100 mg fresh weightof embryogenic callus) when embryogenic suspension were used instead of agar-solidified media (Fki et al, 2003).…”

“…The productivity of embryogenic cell suspension cultures increased 20-fold (from 10 to 200 embryos per month per 100 mg fresh weightof embryogenic callus) when embryogenic suspension were used instead of agar-solidified media (Fki et al, 2003). Zouine et al (2005) reported that cell suspension resulted in higher somatic embryo number compared to solid medium; their induction period was reduced by 2 months. Normally the plant growth regulators are reduced or abandoned in the cell suspension cultures to induce morphogenesis leading to plant regeneration.…”