Introgression of wild species into the cultivated strawberry using synthetic octoploids

Synthetic octoploids reresent one method of integrating wild species germplasm into the cultivated octoploid strawberry. Several strawberry genotypes derived from Guelph synthetic octopoloids and 3–4 generations of outcrossing were evaluted for horticultural performance. Pollen stainability of the genotypes was improved by outcrossing and selection and was not considered a limiting factor to yield. Yield and berry weight of the genotypes improved to a level where several genotypes had yields as good as, or greater than, the mean of the check cultivars. There was no significant difference in the yield of genotypes that were either three or four outcrosses removed from the synthetic octoploids. Some genotypes displayed an everbearing habit accompanied by poor runnering characteristics which may have contributed to their reduced yield in the second season. Synthetic octoploids are composed of a diversity of germplasms distinct from the cultivated octoploid. However, by carefully selecting parents for the outcrossing program and rigorous selection for important horticultural traits, it was possible to restore performance close to the elite level in as few as three generations.     

Genetic diversity and distribution patterns of Ecuadorian capuli (Prunus serotina)

Prunus serotina subsp. capuli (Cav.) is an arboreal species with promising economic prospects in the timber, health-food and neutraceutical markets. Despite its cultural and commercial significance, limited information exists with regards to the degree of genetic variation and ecological history of P. serotina in Ecuador. The main objective of this study was to evaluate the degree of genetic diversity and population structure of Ecuadorian P. serotina, as a preliminary step towards understanding the distribution history of this species in Ecuador and establishing germplasm conservation programs. P. serotina samples (217, representing 8 provinces from the Ecuadorian highlands) were characterized using 8 heterologous SSR markers derived from related Prunus species. Expected heterozygosity across samples (H_e = 0.71) reveals a moderate level of genetic diversity for Ecuadorian P. serotina. Nevertheless, simple allele-count analysis indicates that Ecuadorian capuli has a narrower degree of allelic richness relative to collections from the species’ center of origin in North America. Furthermore, pairwise F statistics (0.0069 ≤ Fst ≤ 0.0319) and Nei genetic distance estimates (0.02 ≤ Ds ≤ 0.09) indicate minimal population differentiation within Ecuadorian capuli. However, Bayesian population structure analysis suggests a subtle genetic contrast between germplasm from the Northern and Southern highlands. Certainly, it is of interest to analyze whether this underlying genetic differentiation between the Northern- and Southern-Highland groups is also manifested in morphological, agronomic or other phenotypic characters that could indicate adaptive differences to divergent agro-ecosystems.     

Development of a spermatogonia cryopreservation protocol for blue catfish,Ictalurus furcatus

Sustainability of channel catfish, Ictalurus punctatus ♀ × blue catfish, Ictalurus furcatus ♂ hybrid aquaculture relies on new innovative technologies to maximize fry output. Transplanting spermatogonial stem cells (SSCs) from blue catfish into channel catfish hosts has the potential to greatly increase gamete availability and improve hybrid catfish fry outputs. Cryopreservation would make these cells readily accessible for xenogenesis, but a freezing protocol for blue catfish testicular tissues has not yet been fully developed. Therefore, the objectives of this experiment were to identify the best permeating [dimethyl sulfoxide (DMSO), ethylene glycol (EG), glycerol, methanol] and non-permeating (lactose or trehalose with egg yolk or BSA) cryoprotectants, their optimal concentrations, and the best freezing rates (−0.5, −1.0, −5.0, −10 °C/min until −80 °C) that yield the highest number of viable type A spermatogonia cells. Results showed that all of these factors had significant impacts on post-thaw cell production and viability. DMSO was the most efficient permeating cryoprotectant at a concentration of 1.0 M. The optimal concentration of each cryoprotectant depended on the specific cryoprotectant due to interactions between the two factors. Of the non-permeating cryoprotectants, 0.2 M lactose with egg yolk consistently improved type A spermatogonia production and viability beyond that of the 1.0 M DMSO control. The overall best freezing rate was consistent at −1 °C/min, but similar results were obtained using −0.5 °C/min. Overall, we recommend cryopreserving blue catfish testicular tissues in 1.0 M DMSO with 0.2 M lactose and egg yolk at a rate of either -0.5 or −1 °C/min to achieve the best cryopreservation outcomes. Continued development of cryopreservation protocols for blue catfish and other species will make spermatogonia available for xenogenic applications and genetic improvement programs.     

Seed protein electrophoresis in taxonomic and evolutionary studies

Summary Seed protein electrophoresis is increasingly being utilized as an additional approach for species identification and as a useful tool for tracing back the evolution of various groups of plants. This paper summarizes the main features of the seed protein profile — stability, uniformity and additive nature. In addition, the significance of this approach for resolving specific taxonomic and evolutionary problems is pointed out.     

Introduction and conclusions for a Discussion entitled Land resources: on the edge of the Malthusian precipice?

Introduction and conclusions for a Discussion hosted by the Ciba Foundation and entitled Land resources: on the edge of the Malthusian precipice? Discussion held on the 4th and 5th December 1996, and organized and edited by D. J. Greenland, P. J. Gregory and P. H. Nye. <br>     

三种荆州半夏的ITS序列分析与种属鉴定

通过采集自湖北荆州地区的三种不同表现型的半夏属植物的叶片组织中提取基因组,纯化后经直接PCR扩增得到其对应的ITS序列并测序。运用NCBI Gen Bank数据库进行序列比对与进化树分析。根据比对与分析结果,结合植物形态学特征显示,HBB-01为Pinellia ternata,为《中国药典》中规定的半夏类药材品种;HBD-02为P.tripartita,为药用半夏的混淆品;HBF-03的结果较为复杂,其不仅与芋属(Colocasia)天南星属(Arisaema)、半夏属(Pinellia)等植物ITS序列的同源性高达80%以上,而且在进化关系上,它们也有一定关联。所以推测HBF-03可能为天南星科不同属但亲缘关系较近的植物产生的变种,具体种属来源有待进一步论证。通过三种半夏种属来源及其亲缘关系的分析,鉴定了荆州地区的半夏人工种植的主要品种,对其当地药农种植符合《中国药典》规范的半夏药材具有指导意义,为后续优质半夏资源的保护与选育提供了参考依据。     

The environmental implications of intensified land use in developing countries

The major agricultural intensifications in the developed world over the last half century have produced a range of important environmental problems. These include pollution, damage to wildlife and landscape and other issues, both on- and off-site. These are largely being controlled by scientific investigation and Government regulation. As developing countries increase agricultural production over the next 30 years, this may also cause even more serious environmental damage.<br>The paper distinguishes between production-related on-site damage, and off-site and more extensive effects. Both may involve soil and water effects, such as soil erosion, salinization, siltation, eutrophication and loss of water quality. The use of more agrochemicals can damage water quality, health, wildlife and biodiversity. Loss of habitat from the extension of farming is particularly damaging to biodiversity. A developing off-site problem is the production of greenhouse gases by farming systems, including the conversion of forests to farmland. In the future the introduction of genetically engineered species of plants, animals or microbes will need secure control.<br>Work, probably on a catchment basis, is necessary to understand and control these problems. The three main requirements are much better environmental information from the developing world; the selection of environmental indicators to be monitored; and the support of local farmers in protecting the environment. There are encouraging indications of farmer concern and action over obvious on-site damage, but this may not extend to extensive off-site issues. The main danger is that developing food scarcity would cause the environmental issues to be ignored in a race for production. <br>