Forest trees are renewable sources of timber and other valuable non-timber products. Nowadays, the increase in population and demand for forestry products results in overexploitation of forestry. Therefore, there is an urgent need to produce elite plants with higher productivity under stress derived from climate change to have available to afforestation. For this reason, propagation methods should be improved to be more efficient in terms of quality and productivity. The main species planted in the Basque Country is Pinus radiata; during the last three years, Pinus radiata plantations have suffered a fungus attack affecting mainly needles until the tree's death. This crisis is caused by the combined action of two fungi of the genus Dothistroma and Lecanosticta acicola, whose expansion seems to have been enhanced by weather-related factors, such as humid and hot summers. Although we have evidence of this disease's presence in our mountains since 1942, the disease has had a speedy expansion with an aggressive effect for reasons that are not scientifically known today. For the above, Basque Country forestry sector is looking for alternative species to be used in its plantations. Part of the forestry sector considers that Sequoia sempervirens could be a good choice for plantations. Besides, its high-quality wood and its tolerance to the attack of several pathogens and other diseases derived from climate change are characteristics that could confer some advantage over other forest species. The main goal of this study was to optimize the micropropagation of adult elite trees of Sequoia sempervirens. The effect of 6-benzylaminopurine, meta-Topolin and Kinetin, and 4 types of explant in the multiplication stage were analyzed to carry out this objective. Furthermore, the effect of two types of auxins: 1-naphthalene acetic acid, indole-3-butyric acid, and a mixture of both, were evaluated on the induction of roots and their subsequent effect on the acclimatization process. The best multiplication index was obtained when 4.4 µM 6-benzylaminopurine and apical explants longer than 1.5 cm of length were used. The root induction percentage was 75% in the most responsive genotype analyzed when 4.4 µM 6-benzylaminopurine was used on the induction stage, and 50 µM of 1-naphthalene acetic acid was used for rooting. Finally, after 3 months in the greenhouse, the explants cultured with Kinetin and rooted in a culture medium with indole-3-butyric acid showed the highest acclimatization success (94%).
In Costa Rica Albizia guachapele, Cedrela odorata, Platymiscium pinnatum and Guaiacum sanctum are important plant species in both economic and ecological terms and their wood is precious and reported to be highly resistant material. This research has evaluated the in vitro micropropagation as a technology focused to conserve these species. Findings include percentage of germination of seeds and contamination, induction of buds, rooting and growth of microcuttings of these four species.
Genetic improvement programs for conifer forest species face the challenge of propagating elite individuals with superior characteristics in the present landscape of climate change; the problem is focused on the fact that when these individuals have shown the desirable traits, they have changed phase and therefore have lost the ability to be propagated by traditional methods. Based on our previous works on Pinus spp. regeneration of adult trees through organogenesis and trying to improve the protocol in Pinus radiata, our objective was to analyze the influence of collection dates and different 6-benzyladenine (BA) concentrations in the first phase of shoot induction, as well as the effect of different light types on the success of root induction. Moreover, we were interested in studying the effect of the abovementioned physico-chemical factors on the amino acid and carbohydrate content in the shoots developed in vitro. Reinvigorated shoots were obtained in both BA concentrations (22 or 44 μM), although the highest BA concentration showed the best results in terms of shoot induction (explants forming shoots (46%) and number of shoots per explant (1.95 ± 0.52)) when using initial explants collected in the first week of February. The percentage of explants forming shoots (EFS) was genotype-dependent. Explants from genotype A induced with the highest BA concentration showed the highest EFS (91%). With respect to the light treatment applied, significant differences in root induction (20%) and in the number of roots per explant (4.62 ± 0.65) were observed in shoots cultured under white FL. Finally, significant differences in different phases of the rooting process were detected in the amounts of fructose, glucose and sucrose and in the content of threonine and tyrosine.
INTRODUCTION:A protocol for the in vitro culture of the anxiolytic medicinal plant Souroubea sympetala (Marcgraviaceae) was developed, representing one of the first in vitro cultures for the family. This species was previously very difficult to cultivate from seed or cuttings. METHODS:Methods included (1) the improvement of seed germination by axenic culture (2) development of regenerative cultures in vitro, then cultivation under greenhouse and finally field conditions and (3) creation of cell suspensions. Phytochemical analysis was undertaken by liquid chromatography coupled to mass spectrometry (HPLC-MS). RESULTS:The percentage of seed germination was improved from 2% to 59% in axenic culture and the full development of the seedling with its apical shoot and root took twenty-four days. The best seedling development was obtained in Gamborg B5 culture medium. Most friable callus formation, (66.7%) was obtained in the Murashige and Skoog medium supplemented with naphthalene acetic acid (1 mg • L -1 ) and kinetin (0.5 mg • L -1 ) from which viable cell cultures were developed. Analysis identified 4 main triterpenes with both in vitro plants and greenhouse grown plants derived from them. The triterpenes were betulinic acid, ursolic acid, alpha-amyrin and beta-amyrin. The betulinic acid found in greenhouse plants was comparable to wild plants. The cell suspension cultures had much lower levels of betulinic acid than plants and are not at present a viable source of this anxiolytic triterpene. DISCUSSION: The improvement in seed germination of this recalcitrant tropical species was highly successful. The subsequent in vitro propagation and progression of plants through greenhouse and field conditions to provide mature plants with active principle concentrations comparable to wild plants was promising. Friable callus was achieved but phytochemical analysis showed that the level of betulinic acid in callus was much lower than that found in mature plant tissue. CONCLUSION:The method provides healthy plants for cultivation of this new medicinal plant and consequently harvesting of wild plants is not required.
Pinus. ponderosa (P. Lawson and C. Lawson) is a commercial tree and one of the most important forest species in North America. Ponderosa pine suffers hardship when going through vegetative propagation and, in some cases, 15–30 years are needed to achieve full reproductive capacity. Based on previous works on P. ponderosa regeneration through in vitro organogenesis and trying to improve the published protocols, our objective was to analyze the influence of different types of explants, basal culture media, cytokinins, auxins, and light treatments on the success of shoot multiplication and rooting phases. Whole zygotic embryos and 44 µΜ 6-benzyladenine showed the best results in terms of explants survival. For shoot organogenesis, whole zygotic embryos and half LP (LP medium, Quoirin and Lepoivre, 1977, modified by Aitken-Christie et al., 1988) macronutrients were selected. A significant positive interaction between whole zygotic embryos and half LP macronutrients was found for the percentage of explants forming shoots. Regarding the light treatments applied, a significantly higher percentage of shoots elongated enough to be rooted was detected in shoots growing under blue LED at a light intensity of 61.09 µmol m−2 s−1. However, the acclimatization percentage was higher in shoots previously cultivated under fluorescent light at a light intensity of 61.71 µmol m−2 s−1. Anatomical studies using light microscopy and scanning electron microscopy showed the light treatments promoted differences in anatomical aspects in in vitro shoots; needles of plantlets exposed to red and blue LEDs revealed less stomata compared with needles from plantlets exposed to fluorescent light.
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