Somatic embryogenesis and plant regeneration of cassava (Manihot esculenta Crantz) landraces from Cameroon

Abstract

A procedure to regenerate cassava (Manihot esculenta Crantz) cultivars from Cameroon via somatic embryogenesis (SE) was developed. Shoot apical meristems and immature leaf lobes were used as explants on Murashige and Skoog (MS) basal medium containing 33 or 50 µM of the auxins Picloram (Pic), 2,4-Dichlorophenoxyacetic acid (2,4-D), Dicamba (Dic), and α-Naphthalene acetic acid. Cultivar performance was assessed using SE and number of somatic embryos produced. Overall, the frequency of primary somatic embryogenesis (PSE) and the mean number of somatic embryos produced varied considerably with genotype, type of auxin and concentration tested. For example, cultivar (cv.) Ngan Mbada showed the best performance on MS medium supplemented with 50 µM Pic with a SE frequency of 40 % and an average number of somatic embryos of 90. The second best performance was recorded in cv. Local Red on MS medium supplemented with 33 µM 2,4-D, where the SE frequency was 40 % and an average number of somatic embryos of 60.5. Cultivar Ekona Red recorded the best performance on medium supplemented with 50 µM Pic showing a SE frequency of 47 % and an average number of somatic embryos of 45. We further examined secondary and cyclic somatic embryogenesis (SSE, CSE) and both were also observed to vary with genotype, however, both exhibited significantly higher frequencies of SE compared with PSE. SE started to decline at the fourth cycle of embryogenesis. Examination of organogenesis showed that shoot bud induction from green cotyledons varied across cultivars and benzylaminopurine was shown to outperform Thidiazuron in the ability to induce organogenesis. Furthermore, the frequencies of bud induction were identical under light and dark conditions. Finally, regenerated plants grew easily in the greenhouse with 90–100 % survival rate and did not display detectable variation in morphology.

Induksi dan Proliferasi Embriogenesis Somatik In Vitro pada Lima Genotipe Kedelai

“…Hasil percobaan ini menunjukkan bahwa penambahan NAA 10 mg L -1 yang dikombinasikan dengan 2,4-D 10 mg L -1 mampu menginduksi pembentukan embrio somatik yang kemudian berkembang menjadi ES (torpedo dan kotiledon). NAA merupakan jenis auksin yang diduga berperan dalam proses pembentukan dan pematangan embrio somatik, khususnya mempengaruhi morfologi embrio yang terbentuk (Mongomake et al, 2015).…”

“…Hal ini seperti dikemukakan oleh von Arnold et al (2002) bahwa kalus embriogenik biasanya dipelihara dan mengalami proliferasi pada medium yang sama dengan yang digunakan pada media inisiasi, seperti juga yang digunakan pada kultur cair untuk propagasi skala besar. Proses proliferasi demikian dinamakan juga embriogenesis sekunder atau embriogenesis yang berulang (Moura et al, 2009;Mongomake et al, 2015).…”

Optimisation of Somatic Embryogenesis in Cassava

“…The use of 2,4-D for embryo initiation often results in low frequency of primary embryo production as well as poor conversion into plants due to lack of root primordium especially when duration of calli production on the initiation medium is prolonged (Raemakers 1993). More recently, many authors have reported of the successful use of other synthetic auxins such as picloram (4-amino-3,5,6-tricloropiconic acid) and dicamba (3,6-dichloroanisic acid) (Mongomake et al 2015). The application of new generation of growth regulators such as oligosaccharides, jasmonate, polyamines, brassinosteroids (George et al 2008) and phloroglucinol (Teixeira da Silva et al 2013) has also proved to be useful for primary somatic embryos induction in many plant species.…”

Recent Biotechnological Advances in the Improvement of Cassava

“…The most reliable regeneration system cassava so far is through somatic embryogenesis (Figure 2) [5]. In the case of conventional breeding, which so far is the most routinely used approach to improve this crop is challenging due to several factors associated with several factors, include: (1) Lack of useful genes in the core cassava germplasm collections; (2) Heterozygosity and allopolyploidy of the cassava genomes; (3) Irregular flowering; Figure 2.…”

“…In the case of conventional breeding, which so far is the most routinely used approach to improve this crop is challenging due to several factors associated with several factors, include: (1) Lack of useful genes in the core cassava germplasm collections; (2) Heterozygosity and allopolyploidy of the cassava genomes; (3) Irregular flowering; Figure 2. Regeneration of cassava cultivars from Cameroon [5]. Callus with proembryogenic masses (A); clusters of organized embryogenic structures consisting of globular, heart and torpedo structures, early cotyledonary stage, asynchronous development of somatic embryos (B); organogenic callus with green cotyledons developed clusters of shoot buds (C); shoot buds rooted and developed into whole plantlets in vitro (D).…”