Establishment of an Efficient Micropropagation System for Humulus lupulus L. cv. Cascade and Confirmation of Genetic Uniformity of the Regenerated Plants through DNA Markers

The demand for virus-free hop planting material has increased in the last few years due to its multipurpose uses. The present study aimed to establish an effective protocol for clonal propagation of cv. Cascade using only the cytokinins as PGRs in all stages of micropropagation: (i) in vitro culture initiation using single-node micro-cuttings inoculated on modified Murashige and Skoog (MSm) medium solidified with Plant agar and supplemented with 0.5 mg L−1 6-benziyladenine (BA) with 76% recorded viability of nodal explants; (ii) in vitro multiplication of multinodal shoots on MSm medium gelled with Plant agar and supplemented with different types and concentrations of cytokinins: 2 mg L−1 kinetin (KIN), 0.7 mg L−1 1-(2-Chloro-4-pyridyl)-3-phenylurea) (1 CPPU), 2 mg L−1 meta-topoline (mT) and 0.5 mg L−1 BA, which was the best variant for shoot proliferation (9.48 ± 0.78 shoots/explant); (iii) rooting and acclimatization with the best results obtained by ex vitro rooting and acclimatization of plants in the same stage in perlite (96.00 ± 0.60% acclimatized rooted plants with 100% survival under greenhouse conditions). The true-to-type nature of in vitro raised plants with the mother plant was assessed by Random Amplified Polymorphic DNA (RAPD) and Start Codon Target Polymorphism (SCoT) molecular markers, and then their genetic uniformity were confirmed.

High dynamic dilutions and genetic variability to phytosanitary management and yield of beans (Phaseolus vulgaris L)

The substitution of landrace populations of beans (Phaseolus vulgaris L.) by commercial cultivars provided genetic uniformity and loss of rusticity. It makes the bean plants more vulnerable to pests, increasing the use of pesticides. The objective of this work was to evaluate the productivity and health of beans landraces compared to commercial cultivars, reducing the effect of high dynamic dilutions. The evaluated traits were grain yield (kg ha-1), thousand grain weight (g), and occurrence of anthracnose (Colletotrichum lindemuthianum) and bacteriosis (Xanthomonas sp.). Evaluation of high dynamic dilutions was also done in addition to the previous variables, was evaluated number of pods per plant and pods with the presence of anthracnose. The analysis of the data did not show any differences in the productivity and disease rate between the landraces and the commercial cultivars of beans. The high dynamic dilutions do not show any conclusive results in terms of productivity. However, all treatments were superior in phytosanitary management compared to control

Genetic Uniformity of the MSXJ papaya hybrid (Carica papaya L.) during Micropropagation

Objective: To analyze the genetic uniformity of MSXJ hybrid papaya in vitro plants, obtained by direct organogenesis.Design/Methodology/Approach: The MSXJ papaya hybrid demonstrates quality characteristics for the national and exports market. In vitro culture of plant tissues represents a useful tool for their multiplication and conservation, but somaclonal variation can diminish their genetic and agronomic uniformity. In order to analyze the genetic uniformity of in vitro plants of this hybrid, ten ISSR primers were used for in vitro plants micropropagated during nine subcultures. DNA was extracted using the CTAB method. Data were analyzed using the program PopGene v 1.3.1.Results: Eighty-five loci of 200 to up to 2000 pb were generated, with 37 polymorphic loci. In the cluster analysis, three groups were observed which separate subculture one, subcultures two to eight, and subculture nine; the Gst value of 0.87 indicated genetic uniformity as far as subculture eight.Study Limitations/Implications: Papaya is one of the most important tropical fruits worldwide; however, these plants need to be healthy and genetically uniform to guarantee commercial success. In vitro propagation allows obtaining healthy and uniform plants, but it is necessary to study genetic uniformity during their micropropagation.Findings/Conclusions: The in vitro multiplication of the MSXJ papaya hybrid permitted the regeneration of vigorous plants in 30 d. Molecular profiles indicate that as far as subculture eight, there is genetic uniformity. As such, no more thaneight subcultures are recommended during micropropagation.

Cellular mechanisms of heterogeneity in NF2-mutant schwannoma

Schwannomas are common sporadic nervous system tumors and diagnostic features of familial neurofibromatosis type 2 (NF2) that develop predominantly on cranial and spinal nerves and cause severe neurological deficits and significant morbidity. Virtually all schwannomas result from inactivation of the NF2 tumor suppressor gene with few, if any, cooperating mutations. Despite their genetic uniformity schwannomas exhibit remarkable clinical and therapeutic heterogeneity, which has impeded the success of early rational therapies. An understanding of how heterogeneity develops in NF2-mutant schwannomas is critically needed to improve therapeutic options for these patients. We have found that loss of the membrane:actin cytoskeleton-associated NF2 tumor suppressor protein, merlin, yields unstable intrinsic polarity and enables Nf2-/- SCs to adopt distinct programs of coordinated autocrine ErbB ligand production, polarized signaling and metabolism according to nutrient availability. We validated biomarkers of these programs in a well-established mouse model of schwannoma. Our studies suggest a self-generating model of heterogeneity and identify biomarkers that can now be mapped to the variable clinical and therapeutic behaviors of human schwannomas.

Evaluation of genetic fidelity of in vitro-propagated blackberry plants using RAPD and SRAP molecular markers

The aim of this research was to evaluate the genetic uniformity of blackberry plants (Rubus fruticosus L. ‘Loch Ness’ and ‘Chester Thornless’) obtained by micropropagation. Genetic uniformity was analysed by using RAPD and SRAP markers. For the in vitro multiplication, the slightly modified Murashige and Skoog (1962) basal medium was used, supplemented with 0.5 mg/l 6-Benzyladenine (BA), prepared with tap water and 50 g/l wheat starch as the gelling agent. This culture medium ensured the regeneration of well-developed plantlets, with multiplication rates of more than 42 for both cultivars. The in vitro multiplication was carried out in 30 months including 12 subcultures. The plants obtained from the 3rd and 11th subcultures were compared with the mother plants using 64 SRAP primer combinations (eight forward and eight reverse primers) and 20 RAPD primers to check their genetic fidelity. The amplification products were monomorphic in the micropropagated plants and the mother plant. No polymorphism was detected, thus proving the genetic fidelity and uniformity of the micropropagated plants.