Picolinic acid-induced direct somatic embryogenesis in sweet potato

Abstract

Somatic embryos are being considered as an alternative material for in vitro germplasm conservation of sweet potato [(Ipomoea batatas (L.) Lam.)]. Picolinic acid was tested for somatic embryo production in sweet potato apical meristem tip cultures. Low level (0.2 mg1-1) of picolinic acid combined with kinetin or 6-benzylamino purine (6-BAP) (1.0 and 2.0 mg1-1) suppressed shoot growth and induced callus proliferation. Increased amount of picolinic acid (2 and 3 mg1-1) in combination with kinetin (0.25 and 1.0 mg1-1) induced direct somatic embryogenesis from apical meristem tips of variety Regal but not in Jewel. The primary embryos matured and germinated bipolarly yielding whole plantlets and unipolarly producing embryogenic hyperhydrated-fasciated shoots. The hyperhydrated-fasciated shoots, when cultured in picolinic and kinetin-enriched medium, produced secondary embryos. The secondary embryos also germinated bipolarly and unipolarly, resulting in subsequent cycles of embryogenesis. This recurrent embryogenesis ensures maintenance and proliferation of embryogenic tissues. Somatic embryos were also formed in mannitol-induced hyperhydrated shoots in response to picolinic acid and kinetin or 6-BAP treatment. Embryogenesis did not occur in non-hyperhydrated leaf, petiole, and internode sections.

Effect of genotype, gelling agent, and auxin on the induction of somatic embryogenesis in sweet potato (Ipomoea batatas Lam.)

“…Similarly, cv. Jewel, which was used in several breeding programs of sweet potato, was also reported to be unable to give an embryogenic response [11,35].…”

“…Among various systems of plant regeneration, somatic embryogenesis is highly desired, as the process regularly provides high multiplication rates and can effectively be maintained for a long time. Genotype has been shown to be a limiting factor in induc-tion of somatic embryogenesis, as many cultivars of sweet potato gave low or no embryogenic responses at all [9][10][11]. Rapid and repetitive plant regeneration via somatic embryogenesis was demonstrated in only one genotype of sweet potato, PI318846-3 [12].…”

La embriogénesis somática en Ipomoea : una posibilidad para la multiplicación y conservación de los recursos vegetales

“…El uso de la embriogénesis somática como un método de regeneración de plantas puede facilitar el desarrollo de técnicas mecánicas que permitirían la siembra directa de este cultivo a diferencia de la propagación vegetativa convencional (Cantliffe et al, 1988;Shultheis et al, 1990;Harrel et al, 1992;Desamero et al, 1994;Bieniek et al, 1995). Según Chée et al (1992), la embriogénesis somática en el boniato ofrece una oportunidad para la integración y automatización de la multiplicación clonal rápida y la siembra.…”

Efficient plant regeneration from embryogenic suspension cultures of sweetpotato

“…Somatic embryos can also develop into whole plants on the basal medium (Jarret et al, 1984;Liu and Cantliffe, 1984;Liu et al, 1992Liu et al, , 1993Tan et al, 1993;Desamero et al, 1994;Otani and Shimada, 1996;Wang et al, 1998). However, in most cases evidence for somatic embryogenesis and plant regeneration at a high frequency has been restricted to one or a few genotypes, and when attempts were made to extend this into a wide range of genotypes, the majority were found to be recalcitrant or to respond at low frequencies (Liu et al, 1993;Desamero et al, 1994;Al-Mazrooei et al, 1997;Wang et al, 1998). Thus, it is essential to develop an efficient system of somatic embryogenesis and plant regeneration for a wide range of sweetpotato genotypes.…”