Induction and characterization of oil palm (Elaeis guineensis Jacq.) pro-embryogenic masses.
Oil palm is one of the most economically valuable oil seed plants, but the expansion of plantations has been limited by availability of seedlings, as the conventional propagation is through seeds, which have low germination rates. One possible solution for the large-scale production is the use of somatic embryogenesis. The aim of this study was evaluate the effects auxins 2,4-D and picloram on the induction of pro-embryogenic masses in E.guineenesis hybrid leaf explants and characterize, regarding embryogenic characteristics, with cytochemical and ultrastructural analysis. Specifically, in vitro plantlets leaves fragments were inoculated in Y3 culture medium supplemented by 2.4-D or picloram at different concentrations (0.0, 1.0, 3.0, 6.0 and 9.0 mg l⁻¹). After 90 days the presence/ absence of cell masses were evaluated. Both growth regulators efficiently induced cellular masses regardless of the concentrations applied. As the cell masses were not homogeneously formed, they were classified according to color and shape into four types: TYPE 1--elongated and translucent, TYPE 2--uneven and translucent, TYPE 3--globular and beige, TYPE 4--globular and white. Based on the anatomical and ultrastructural features, TYPE 2, 3 and 4 cell masses were considered to have the highest embryogenic potential and therefore may be most suited to large-scale vegetative propagation of oil palm.
Biotization of in vitro calli and embryogenic calli of oil palm (Elaeis guineensis Jacq.) with diazotrophic bacteria Herbaspirillum seropedicae (Z78)
A continuous discovery of novel practices for in vitro plant culture is essential to promote better plant growth. An alternative approach to the conventional micropropagation practice could be achieved through biotization by supplying selected diazotrophs to the plant materials. Due to this considerable potential, an artificial symbiosis was created between the Herbaspirillum seropedicae strain Z78 (ATCC 35893) and in vitro oil palm (Elaeis guineensis Jacq.). This experiment was carried out with the aim of studying the effects of H. seropedicae inoculation on growth of oil palm calli and embryogenic calli. A total of 4 treatments were tested for calli and embryogenic calli of oil palm on modified Murashige–Skoog medium, namely: T1: 100 % nitrogen source + 100 % 2,4D; T2: 25 % nitrogen source + 10 % 2,4D; T3: Z78 sonicated cell + 25 % nitrogen source + 10 % 2,4D and T4: Z78 pellet cell + 25 % nitrogen source + 10 % 2,4D. The ability of the inoculum to produce phytohormone indole-3-acetic acid was detected by ultra-performance liquid chromatography. Scanning electron microscopy and transmission electron microscopy showed successful artificial symbiosis of calli and embryogenic calli-bacterium. This study has demonstrated that Z78 pellet cell and sonicated cell have the potential to promote growth of in vitro calli and embryogenic calli of oil palm under symbiosis conditions.
Somatic Embryogenesis in Parana Pine (Araucaria angustifolia (Bert.) O. Kuntze)
Embryogenic cultures of Araucaria angustifolia were induced from dominant and non-dominant zygotic embryos excised from immature seeds proceeding from three different genotypes and five harvest dates. Zygotic embryos were inoculated in inductive culture medium LP and BM supplemented with or without plant growth regulators 2,4-D (5 µM), BA (2 µM) and Kin (2 µM). The genotype of the mother tree and the developmental explant stage affected the induction frequency. In the maintenance phase, embryogenic cultures were maintained at continuous repetitive cell cycles every 20 days in semi-solid or liquid medium. In the maturation phase the culture medium was supplemented with different types and levels of growth regulators, osmotic agents, carbohydrates and derived. Embryogenic cultures inoculated in culture medium supplemented with PEG 3350 (6 and 9%), maltose (6 and 9%), plus BA and Kin (1 µM each) resulted in the progression of somatic embryos to globular and torpedo developmental stages.