Regeneration of Pinus halepensis (Mill.) through Organogenesis from Apical Shoot Buds

Organogenesis and somatic embryogenesis have been widely applied as the two main regeneration pathways in plant tissue cultures. However, recalcitrance is still the main restriction in the clonal propagation of many woody species, especially in conifers. They undergo a “phase change” that leads to significant loss of vegetative propagation capacity, reducing the aptitude of tissues and organs to be regenerated in vitro beyond this point. In line with this, the in vitro regeneration of mature conifer trees has been a long-cherished goal in many laboratories worldwide. Based on previous works in Pinus species regeneration from adult trees, we now present data about the culture of apical shoot buds in an attempt to induce organogenesis and somatic embryogenesis to clone mature trees of Aleppo pine (Pinus halepensis). Reinvigorated axillary shoots were submitted to conditions usually applied to induce somatic embryogenesis through the manipulation of culture media, including the use of auxins such as 2,4-Dichlorophenoxyacetic acid and 1-Naphthaleneacetic acid, cytokinins (6-benzyladenine and kinetin), and phytosulfokine (50, 100, and 200 nM). Although somatic embryos could not be obtained, an embryogenic-like tissue was produced, followed by the emergence of actively proliferating non-embryogenic calli. Variations in the consistence, texture, and color of non-embryogenic calli were observed; especially those arising in the media containing phytosulfokine. Reinvigorated shoots, induced by 22 or 44 µM 6-benzyladenine, were obtained through organogenesis and acclimatized, and phenotypically normal plants were obtained.

Regeneration of Pinus Halepensis (Mill) through Organogenesis from Apical Shoot Buds

Organogenesis and somatic embryogenesis have been widely applied as the two main regeneration pathways in plant tissue culture. However, recalcitrance is still a main restriction in the clonal propagation of many woody species, especially in conifers. They undergo a “phase change” that leads to significant loss of organogenic and embryogenic capacity, thus reducing the responsive tissues or organs to juvenile material, and narrowing the competence window. In this sense, in vitro regeneration of mature conifer trees has been a long-cherished goal in many laboratories worldwide. In this work, apical shoot buds were used as explants for both organogenesis and somatic embryogenesis in order to cloning mature trees of Aleppo pine. Reinvigorated axillary shoots were submitted to somatic embryogenesis induction through the manipulation of culture media, including the use of auxins such as 2,4-D and NAA, cytokinins (BA and kinetin) and phytosulfokine (50, 100 and 200 nM). Although somatic embryos could not be obtained, embryogenic-like tissue was produced followed by the appearance of actively proliferating non-embryogenic calli and differences between treatments were found, especially when phytosulfokine was added to the induction media. Organogenic system produced reinvigorated shoots from both BA treatments tested (22 and 44 µM), from juvenile somatic trees and adult trees, and ex-vitro acclimatized plants were developed.

Pengaruh Iradiasi Sinar Gamma terhadap Pertumbuhan Stek Tunas Apikal dan Aksilar Kopi Arabika

<p><em>The Arabica coffee is predominantly self-pollinated plants thereby contributing to low genetic diversity. The effort to increase the genetic diversity of Arabica coffee through crossing strategy is time-consuming, and induce mutation is necessary to enhance the rate of genetic variation. The aims of this study were to observe the effect of gamma-ray irradiation on the growth of apical and axillary bud cuttings and to determine the value of LD₅₀ on apical cuttings and Arabica coffee axillaries. The study was conducted at the Tissue Culture Laboratory, Industrial and Beverage Crops Research Institute, from January to December in 2018.. The planting material that was irradiated was Arabica coffee plantlets resulting from somatic embryogenesis propagation. Irradiation is carried out at the National Nuclear Energy Agency. The irradiated plantlets were cut and subcultured onto MS medium without growth regulators, 30 g L^-1 sucrose, and 2.5 g L^-1 phytagel were added. The design used a completely randomized design with 10 replications. The treatments tested were the dose of gamma-ray irradiation (0, 10, 20, 30, 40, and 50 Gy). The results showed that gamma-ray irradiation had an effect on all observed parameters. The mortality percentage of apical shoot cuttings began to be found at 30 Gy, while axillary cuttings at 20 Gy increased with an increasing dose of gamma-ray irradiation. The number of shoots and leaves varied between irradiation doses on both apical and axillary cuttings. The LD50 value of apical shoot cuttings was 36.80 Gy, while axillary cuttings were 22.24 Gy</em></p>

Type of Explant Affects In Vitro Development and Multiplication Success of the Rare Halophyte Plant Honckenya Peploides L. Ehrh

The sea sandwort—Honckenya peploides (L.) Ehrh. is—a rare halophilous plant growing on dunes and is an endangered species on the Polish coast. It contributes to the stabilization of volatile sandy substrate, facilitating the colonization of other species. The present study determined the reaction of two types of explant: apical shoot fragments and fragments from a lower portion of the shoot. Apical shoot fragments were used to propagate and root sea sandwort plants due to the positive impact on the development of shoots and roots. Regardless of the plant growth regulators applied in the medium, the lateral meristems on the explants from the lower parts of the shoot stopped growing, and then yellowed and died out. Apical fragments of shoots developed higher and more numerous shoots and longer and more numerous roots than explants, which were fragments collected from lower parts of shoots. The findings indicated that propagation should be conducted on Murashige and Skoog medium with the addition of 1 mg∙dm−3 kinetin, whereas shoots with their apical fragments should be rooted with the addition of 1.5 mg∙dm−3 1-naphthaleneacetic acid. The results also showed that the addition of NaCl at concentrations of 25 and 50 mM did not restrict their growth, thereby indicating the tolerance of the plant to soil salinity. However, an increase in the concentration of NaCl in the medium to 75 mM restricted the development of plants, and the shoots were lower and roots were shorter and less numerous.

Impact of Different Explants and Growth Regulators on In vitro Regeneration of Chrysanthemum

Chrysanthemum is the world’s second most economically important flower crop and commonly known as ‘Autumn Queen’. It belongs to the family Compositeae (Asteraceae). It is native to Asia and northeastern Europe and has been cultivated for more than 2000 years. The present study within vitro regeneration of chrysanthemum was carried out to develop the standardized protocol for organogenesis. In this study, three types of explants viz. apical shoot tip, internodal segment and young leaf along with different concentrations and combinations of growth regulators were used for in vitro regeneration. BAP and KIN were used for in vitro microshoot regeneration and IBA along with 2, 4-D were used for in vitro microroot regeneration. Minimum days (7.00) for microshoot initiation, maximum microshoot initiation percentage (97.00), highest number of microshoot per plantlet (12.00), highest number of leaves per microshoot (14.60) and maximum microshoot length (4.60) at 28 DAC were recorded as best performances by apical shoot tip inoculated into MS medium supplemented with BAP 2.5 mg/L + KIN 0.5 mg/L. On the other hand, minimum days (5.00) for microroot initiation, maximum microroot initiation percentage (97.60), the highest number of microroots per plantlet (11.80) and maximum microroot length (6.20) were obtained from apical shoot tip inoculated into ½ strength MS medium supplemented with IBA 0.2 mg/L + 2, 4-D 0.1 mg/L. In case of microshoot regeneration, the best response was showed by apical shoot tip when inoculated into MS medium supplemented with BAP 2.5 mg/L + KIN 0.5 mg/L and the microrooting of plantlets were best from apical shoot tip inoculated into ½ MS medium supplemented with IBA 0.2 mg/L along with 2, 4-D 0.1 mg/L.