Towards Stunt-Free Lonren Reniform Nematode Resistance by Dissection of an Alien R-Gene Chromosome Segment and Detection of Significant Fungal Interactions

Reniform (Rotylenchulus reniformis) nematodes cost US cotton growers over 130 million dollars per year. Genetic resistance of the wild African species Gossypium longicalyx to reniform nematodes was previously transferred into upland cotton (Gossypium hirsutum L.). LONREN and other cotton lines containing the responsible gene, Ren^(lon), are highly nematode-resistant, but when grown in nematode-infested fields, the seedlings and plants became "stunted". Hypothesized causes include hypersensitivity reaction, per se, and/or increased susceptibility to soil pathogens. My research objectives have been: [1] to develop Ren^(lon)-linked markers and map the Ren^(lon) region at high resolution, [2] to recombine Ren^(lon) and nearby loci and determine if “stunting” is due to linkage drag, [3] to create genomic and germplasm resources for genetic manipulation of chromosome-11, especially Ren^(lon), and [4] to determine if "stunting" is due solely to plant-nematode interactions or involves additional pathogens. Putative SNPs between G. hirsutum and G. longicalyx were collaboratively sequence-aligned to the D5 reference genome. By selecting SNPs aligned to the Ren^(lon)-homeologous region and screening them against a genetic panel, we identified 85 as Ren^(lon) -linked. To enable large-scale SNP applications, we developed inexpensive methods for high-throughput non-destructive seed DNA extraction for PCR-based genotyping. We then high-resolution mapped 10 SNPs in the proximal alien segment near Ren^(lon). We chose the two closest Ren^(lon)-flanking SNPs and used them for marker-assisted selection to identify 5 recombinants from 17,600 BC1F1 seed. Subsequent progeny tests indicated 2 of the 5 recombinants were free of "stunting" and that 1 seems to be segregating for nematode resistance. Contingent on verification of the resistance, the results indicate that stunting of LONREN seedlings is indeed due to linkage drag, not hypersensitivity, per se. To determine if "stunting" can be ascribed solely to hypersensitivity-induced root damage, we conducted three replicated growth chamber experiments with multiple genotypes, pasteurized and natural soils, and several pathogen treatments. The results showed that Thielaviopsis root rot alone can cause severe seedling "stunting", but not the nematodes, alone. Moreover, they showed that LONREN-like genotypes are differentially sensitive to the combined presence of reniform nematodes and Thielaviopsis, and become more severely stunted

Development and bin mapping of gene-associated interspecific SNPs for cotton (Gossypium hirsutum L.) introgression breeding efforts

BACKGROUND: Cotton (Gossypium spp.) is the largest producer of natural fibers for textile and is an important crop worldwide. Crop production is comprised primarily of G. hirsutum L., an allotetraploid. However, elite cultivars express very small amounts of variation due to the species monophyletic origin, domestication and further bottlenecks due to selection. Conversely, wild cotton species harbor extensive genetic diversity of prospective utility to improve many beneficial agronomic traits, fiber characteristics, and resistance to disease and drought. Introgression of traits from wild species can provide a natural way to incorporate advantageous traits through breeding to generate higher-producing cotton cultivars and more sustainable production systems. Interspecific introgression efforts by conventional methods are very time-consuming and costly, but can be expedited using marker-assisted selection. RESULTS: Using transcriptome sequencing we have developed the first gene-associated single nucleotide polymorphism (SNP) markers for wild cotton species G. tomentosum, G. mustelinum, G. armourianum and G. longicalyx. Markers were also developed for a secondary cultivated species G. barbadense cv. 3–79. A total of 62,832 non-redundant SNP markers were developed from the five wild species which can be utilized for interspecific germplasm introgression into cultivated G. hirsutum and are directly associated with genes. Over 500 of the G. barbadense markers have been validated by whole-genome radiation hybrid mapping. Overall 1,060 SNPs from the five different species have been screened and shown to produce acceptable genotyping assays. CONCLUSIONS: This large set of 62,832 SNPs relative to cultivated G. hirsutum will allow for the first high-density mapping of genes from five wild species that affect traits of interest, including beneficial agronomic and fiber characteristics. Upon mapping, the markers can be utilized for marker-assisted introgression of new germplasm into cultivated cotton and in subsequent breeding of agronomically adapted types, including cultivar development. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (doi:10.1186/1471-2164-15-945) contains supplementary material, which is available to authorized users

Case Report: Chronic hepatitis E virus Infection in an individual without evidence for immune deficiency

Chronic hepatitis E virus (HEV) infection occurs mainly in immunosuppressed populations. We describe an investigation of chronic HEV infection of genotype 3a in an individual without evidence for immune deficiency who presented hepatitis with significant HEV viremia and viral shedding. We monitored HEV RNA in plasma and stools, and assessed anti-HEV specific immune responses. The patient was without apparent immunodeficiency based on quantified results of white blood cell, lymphocyte, neutrophilic granulocyte, CD3+ T cell, CD4+ T cell, and CD8+ T cell counts and CD4/CD8 ratio, as well as total serum IgG, IgM, and IgA, which were in the normal range. Despite HEV specific cellular response and strong humoral immunity being observed, viral shedding persisted up to 109 IU/mL. After treatment with ribavirin combined with interferon, the indicators of liver function in the patient returned to normal, accompanied by complete suppression and clearance of HEV. These results indicate that HEV chronicity can also occur in individuals without evidence of immunodeficiency

The Curing and Strength Properties of Highly Moist Waste Mud from Slurry Shield Tunnel Construction

The waste mud from slurry shield tunnel construction can easily cause environmental pollution. Thus, the RCSLP curing agent is developed to reutilize the waste mud produced in the Jinan Yellow River tunnel. The strength properties of the soils solidified with cement or RCSLP were tested, and their microstructures were studied by scanning electron microscopy. The results show that for the RCSLP curing agent, an optimum cement content of 15% and an optimum additive content of 12% improved the early compressive strength of the solidified soil. The mechanical properties of the RCSLP solidified soil were improved due to the significantly increased hydration products. The findings of this research could help achieve the utilization of waste mud from slurry shield tunnel construction

The Curing and Strength Properties of Highly Moist Waste Mud from Slurry Shield Tunnel Construction

The waste mud from slurry shield tunnel construction can easily cause environmental pollution. Thus, the RCSLP curing agent is developed to reutilize the waste mud produced in the Jinan Yellow River tunnel. The strength properties of the soils solidified with cement or RCSLP were tested, and their microstructures were studied by scanning electron microscopy. The results show that for the RCSLP curing agent, an optimum cement content of 15% and an optimum additive content of 12% improved the early compressive strength of the solidified soil. The mechanical properties of the RCSLP solidified soil were improved due to the significantly increased hydration products. The findings of this research could help achieve the utilization of waste mud from slurry shield tunnel construction

Modeling the Potential Distribution of Three Taxa of <i>Akebia</i> Decne. under Climate Change Scenarios in China

Akebia trifoliata (Thunb.) Koidz., Akebia trifoliata subsp. australis (Diels) T. Shimizu and Akebia quinata (Houtt.) Decne. are the source plants of the traditional Chinese medicines AKEBIAE CAULIS and AKEBIAE FRUCTUS, and have high pharmaceutical value. However, the resource reserve of these plants has dramatically declined due to habitat destruction, which has seriously affected their adequate supply and sustainable utilization. A poor knowledge of the potential distribution of these medicinal materials would seriously constrain the protective exploitation of wild resources and the establishment of new cultivations. In this study, based on the scenarios of SSP1-2.6, SSP2-4.5, SSP3-7.0 and SSP5-8.5, the maximum entropy model was used to predict the potential distribution of these three Akebia taxa under current and future (2030s, 2050s, 2070s and 2090s) climate conditions. Our findings showed that the potentially suitable areas of these three Akebia taxa were mainly distributed in China at 101.8–121.9° E and 23.5–34.6° N. Temperature played a more significant role than precipitation in affecting the distribution. The dominant bioclimatic variable that affected the distribution of A. trifoliata and A. quinata in China was the minimum temperature of the coldest month (BIO06). For A. trifoliata subsp. australis, the mean diurnal range (BIO02) was the dominant variable influencing its distribution. Compared with current conditions, the moderate- and high-suitability areas of these three Akebia taxa were predicted to shrink towards the core areas, while the low-suitability areas were all observed to increase from the 2030s to the 2090s. With the increase in radiative forcing of SSP, the low-impact areas of these three Akebia taxa showed a decreasing trend as a whole. Our results illustrate the impact of climate change on the distribution of Akebia, and would provide references for the sustainable utilization of Akebia’s resources