124株鹌鹑空肠弯曲菌生物学性状的观察

由鹌鹑分出的１２４株空肠弯曲菌,经鉴定,其形态学特征、培养特性以及生化反应、生长与抑制生长试验的特点等均与人源空肠弯曲菌基本一致,但半数以上菌株具有ａ型溶血性能。按Ｌｉｏｎ生物学分型,主要为Ⅳ型（占７５．８％）,其次是Ⅲ型、Ⅱ型（分别占１７．７％、６．５％）,互型缺如。研究证实,氯化镉对全部菌株均能抑制生长,而０／１２９无此作用。药敏试验表明,鹌鹑空肠弯曲菌依次对氟哌酸、麦迪霉素、氯霉素、呋喃妥因、丁胺卡那霉素、红霉素和链霉素呈现高敏,但均有少数菌株例外;对青霉素类和菌必治则大多数菌株表现耐药。     

江西熊蛛幼蛛各龄期的形态特征

江西熊蛛的幼蛛共蜕皮５次,有６个龄期。对幼蛛各龄期和卵袋的特征作了较详尽的描述。     

Detection of quantitative trait loci on chromosome 5R of rye (Secale cereale L.)

 Progenies of an F₂ mapping population were analyzed for quantitative traits to detect QTLs by using marker information from F₂ plants for chromosome 5R. The mapping population was segregating for the major dwarfing gene Ddw1 and the gene Hp1 for hairy peduncle. The only QTL determining plant height was located between HP1 and Ddw1 on the distal part of chromosome 5RL. At the same position a QTL for peduncle length was found, and this trait was closely related to plant height (r=0.895). Since Hp1 and Ddw1 are dominant marker loci, no dominance effect could be estimated. The QTLs for spike length and the number of florets were located near the centromere on 5RL. These two traits were correlated with r=0.824 and showed partial dominance, but these traits were not correlated to plant height and peduncle length. Homoeologous relationships between the QTLs mapped for the first time in rye and those mapped in other Triticeae members are discussed. Received: 8 June 1998 / Accepted: 8 October 1998     

Nuclear DNA amount,growth, and yield parameters in maize

Extensive nuclear DNA content variation has been observed inZea mays. Of particular interest is the effect of this variation on the agronomic potential of maize. In the present study, yield and growth data were collected on 12 southwestern US maize open-pollinated populations. These populations, originally cultivated by the Indians of the southwestern US for both human and animal consumption and adapted to various altitudes, were grown in replicated plots at the University of Illinois Agronomy-Plant Pathology South Farm. All growth and yield parameters were found to be negatively correlated with nuclear DNA amount. The negative correlations of nuclear DNA amount and growth parameters were more pronounced at 60 days after planting (DAP) than 30 DAP. Agronomically-important yield parameters, such as ear or seed weight and seed number per plant, also exhibited a significant negative correlations with nuclear DNA amount. These correlations demonstrate how the nucleotype may exhibit a high degree of influence on the agronomic phenotype. Although the results presented here represent only three replications at one location in 1 year, the observations noted suggest that nucleotype plays an integral role in determining the agronomic performance of maize. Further studies are needed to fully document this role.     

The challenge of the food sufficiency through salt tolerant crops

This work is focused on deserts, as extreme environments, because the year 2006 has been declared Year of Deserts and Desertification by the United Nations (IYDD Program 2006). The loss of vital resources such as fresh water and soil, and the depletion of biodiversity are emerging hazards, able to transform beneficial situations into extreme environments. Desertification is generated by land degradation: the loss of biological productivity is caused by nature or by human-induced factors and climate change. Nearby the desertification process there is the increasing process of salinisation of soil and water, induced by irrigation itself, or by salt water ingress derived by tsunamis or hurricanes. Increased research on the development of salt-tolerant cultivars could, with appropriate management, result in the broader use of saline soils. Although careful application is necessary, the combination of sand, seawater, sun and salt-tolerant plants presents a valuable opportunity for many developing countries. Cooperation among plant ecologists, plant physiologists, plant breeders, soil scientists, and agricultural engineers could accelerate the development of economic salt tolerant crops. If saline water is available, the introduction of salt tolerant plants in poor regions can improve food or fuel supplies, increase employment, help stem desertification, and contribute to soil reclamation. Contribution to the monograph “Life in Extreme Environments”     

Detection of QTLs Linked to Leaf and Smoke Properties in Nicotiana tabacum Based on a Study of 114 Recombinant Inbred Lines

Quantitative trait loci (QTLs) were investigated in a recombinant inbred line (RIL) population descended from a cross between two flue-cured Nicotiana tabacum L. inbred lines with unrelated breeding origins. A total of 59 traits, related to diverse agronomic, leaf quality, chemical composition and smoke properties were assessed. Chemical traits and smoke mutagenicity were estimated by near infrared reflectance spectroscopy (NIRS) analyses of leaf lamina powders. Physical properties of cigarettes made from each RIL, and the total particulate matter (tar and nicotine yields), benzo[a]pyrene and CO contents of the main smoke stream generated by the cigarettes in mechanical smoking tests under a standard ISO regime were also analyzed. The RILs were screened for 184 amplified fragment length polymorphism (AFLP), inter simple sequence repeat (ISSR), sequence specific amplified polymorphism (SSAP), sequence characterized amplified region (SCAR) and biological markers. A partial genetic map including 18 linkage groups was constructed based on 138 of the markers. Substantial segregation distortion (47%) was observed in linkage groups throughout the genome. Seventy-five QTLs associated with 8–41.5% of the variation in the examined traits were identified on 12 linkage groups by simple and composite interval mapping. Nineteen QTLs had opposite effects to those expected from the ranking of parental means.     

Resequencing 250 Soybean Accessions: New Insights into Genes Associated with Agronomic Traits and Genetic Networks

The limited knowledge of genomic diversity and functional genes associated with the traits of soybean varieties has resulted in slow progress in breeding. In this study, we sequenced the genomes of 250 soybean landraces and cultivars from China, America, and Europe, and investigated their population structure, genetic diversity and architecture, and the selective sweep regions of these accessions. Five novel agronomically important genes were identified, and the effects of functional mutations in respective genes were examined. The candidate genes GSTT1, GL3, and GSTL3 associated with the isoflavone content, CKX3 associated with yield traits, and CYP85A2 associated with both architecture and yield traits were found. The phenotype–gene network analysis revealed that hub nodes play a crucial role in complex phenotypic associations. This study describes novel agronomic trait-associated genes and a complex genetic network, providing a valuable resource for future soybean molecular breeding.     

New and known taxa ofChlorella (Chlorophyceae): Occurrence as lichen phycobionts and observations on living dictyosomes

The algal partner of the lichenPseudocyphellaria carpoloma is a newChlorella species,Chl. sphaerica. It has a saucer- or band-shaped parietal to subparietal chloroplast with a spherical pyrenoid surrounded by a shell of starch. In some of the fully grown cells two dictyosomes lying parallel to each other and changing their position can be observed in the living state. Reproduction occurs by up to 16 autospores. 8 otherPseudocyphellaria species are also lichenized withChlorella phycobionts, apparently belonging toChl. sphaerica. The phycobiont ofWoessia fusarioides belongs toChlorella saccharophila var.ellipsoidea, and to a strain which is morphologically almost identical to one formerly isolated from the lichenTrapelia coarctata. Its ability to gather granules of india ink on the surface of young cells is one of the remarkable characters differentiating it from the latter. In the lichen thallus its cells are regularly penetrated by fungal haustoria.