A protocol for Chenopodium quinoa pollen germination.

BACKGROUND: Quinoa is an increasingly popular seed crop frequently studied for its tolerance to various abiotic stresses as well as its susceptibility to heat. Estimations of quinoa pollen viability through staining methods have resulted in conflicting results. A more effective alternative to stains is to estimate pollen viability through in vitro germination. Here we report a method for in vitro quinoa pollen germination that could be used to understand the impact of various stresses on quinoa fertility and therefore seed yield or to identify male-sterile lines for breeding. RESULTS: A semi-automated method to count germinating pollen was developed in PlantCV, which can be widely used by the community. Pollen collected on day 4 after first anthesis at zeitgeber time 5 was optimum for pollen germination with an average germination of 68% for accession QQ74 (PI 614886). The optimal length of pollen incubation was found to be 48 h, because it maximizes germination rates while minimizing contamination. The pollen germination medium's pH, boric acid, and sucrose concentrations were optimized. The highest germination rates were obtained with 16% sucrose, 0.03% boric acid, 0.007% calcium nitrate, and pH 5.5. This medium was tested on quinoa accessions QQ74, and cherry vanilla with 68%, and 64% germination efficiencies, respectively. CONCLUSIONS: We provide an in vitro pollen germination method for quinoa with average germination rates of 64 and 68% on the two accessions tested. This method is a valuable tool to estimate pollen viability in quinoa, and to test how stress affects quinoa fertility. We also developed an image analysis tool to semi-automate the process of counting germinating pollen. Quinoa produces many new flowers during most of its panicle development period, leading to significant variation in pollen maturity and viability between different flowers of the same panicle. Therefore, collecting pollen at 4 days after first anthesis is very important to collect more uniformly developed pollen and to obtain high germination rates.

Heating quinoa shoots results in yield loss by inhibiting fruit production and delaying maturity.

Increasing global temperatures and a growing world population create the need to develop crop varieties that provide higher yields in warmer climates. There is growing interest in expanding quinoa cultivation, because of the ability of quinoa to produce nutritious grain in poor soils, with little water and at high salinity. The main limitation to expanding quinoa cultivation, however, is the susceptibility of quinoa to temperatures above approximately 32°C. This study investigates the phenotypes, genes and mechanisms that may affect quinoa seed yield at high temperatures. Using a differential heating system where only roots or only shoots were heated, quinoa yield losses were attributed to shoot heating. Plants with heated shoots lost 60-85% yield as compared with control plants. Yield losses were the result of lower fruit production, which lowered the number of seeds produced per plant. Furthermore, plants with heated shoots had delayed maturity and greater non-reproductive shoot biomass, whereas plants with both heated roots and heated shoots produced higher yields from the panicles that had escaped the heat, compared with the control. This suggests that quinoa uses a type of avoidance strategy to survive heat. Gene expression analysis identified transcription factors differentially expressed in plants with heated shoots and low yield that had been previously associated with flower development and flower opening. Interestingly, in plants with heated shoots, flowers stayed closed during the day while the control flowers were open. Although a closed flower may protect the floral structures, this could also cause yield losses by limiting pollen dispersal, which is necessary to produce fruit in the mostly female flowers of quinoa.

Translating Nanomedicine to Comparative Oncology-the Case for Combining Zinc Oxide Nanomaterials with Nucleic Acid Therapeutic and Protein Delivery for Treating Metastatic Cancer.

The unique anticancer, biochemical, and immunologic properties of nanomaterials are becoming a new tool in biomedical research. Their translation into the clinic promises a new wave of targeted therapies. One nanomaterial of particular interest are zinc oxide (ZnO) nanoparticles (NPs), which has distinct mechanisms of anticancer activity including unique surface, induction of reactive oxygen species, lipid oxidation, pH, and also ionic gradients within cancer cells and the tumor microenvironment. It is recognized that ZnO NPs can serve as a direct enzyme inhibitor. Significantly, ZnO NPs inhibit extracellular signal-regulated kinase (ERK) and protein kinase B (AKT) associated with melanoma progression, drug resistance, and metastasis. Indeed, direct intratumoral injection of ZnO NPs or a complex of ZnO with RNA significantly suppresses ERK and AKT phosphorylation. These data suggest ZnO NPs and their complexes or conjugates with nucleic acid therapeutic or anticancer protein may represent a potential new strategy for the treatment of metastatic melanoma, and potentially other cancers. This review focuses on the anticancer mechanisms of ZnO NPs and what is currently known about its biochemical effects on melanoma, biologic activity, and pharmacokinetics in rodents and its potential for translation into large animal, spontaneously developing models of melanoma and other cancers, which represent models of comparative oncology.