Interdisciplinary Team Addresses Cotton Leafroll Dwarf Virus in Alabama

A multi-state and interdisciplinary team was formed to address the Extension and research needs of CLRDV, an emerging cotton disease with high potential impact for U.S. cotton production. In 2017, CLRDV was identified in AL and Auburn University immediately formed an interdisciplinary working group composed of plant breeders, plant pathologists, entomologists, and agronomists. Since then, scientists from ten other states have joined the CLRDV group. Thus, allowing research to be coordinated efficiently and best deploy limited resources to attend the stakeholder’s needs. The CLRDV group produces and shares new and relevant information with the scientific community and cotton producers alike

The effect of root exudates on rhizosphere water dynamics

L.J.C. and N.K. are funded by BBSRC SARISA BB/L025620/1, L.J.C. is also funded by EPSRC EP/P020887/1. K.R.D. is funded by ERC 646809DIMR. P.D.H. and T.S.G. are funded by BBSRC BB/J00868/1. The James Hutton Institute receives funding from the Scottish Government. T.R. is funded by BBSRC SARISA BB/L025620/1, EPSRC EP/M020355/1, ERC 646809DIMR, BBSRC SARIC BB/P004180/1 and NERC NE/L00237/1. Data supporting this study are available on request from the University of Southampton repository at https://doi.org/10.5258/SOTON/D0609 [35].Peer reviewedPublisher PD

Surface tension, rheology and hydrophobicity of rhizodeposits and seed mucilage influence soil water retention and hysteresis

Aims: Rhizodeposits collected from hydroponic solutions with roots of maize and barley, and seed mucilage washed from chia, were added to soil to measure their impact on water retention and hysteresis in a sandy loam soil at a range of concentrations. We test the hypothesis that the effect of plant exudates and mucilages on hydraulic properties of soils depends on their physicochemical characteristics and origin.Methods: Surface tension and viscosity of the exudate solutions were measured using the Du Noüy ring method and a cone-plate rheometer, respectively. The contact angle of water on exudate treated soil was measured with the sessile drop method. Water retention and hysteresis were measured by equilibrating soil samples, treated with exudates and mucilages at 0.46 and 4.6 mg g−1 concentration, on dialysis tubing filled with polyethylene glycol (PEG) solution of known osmotic potential.Results: Surface tension decreased and viscosity increased with increasing concentration of the exudates and mucilage in solutions. Change in surface tension and viscosity was greatest for chia seed exudate and least for barley root exudate. Contact angle increased with increasing maize root and chia seed exudate concentration in soil, but not barley root. Chia seed mucilage and maize root rhizodeposits enhanced soil water retention and increased hysteresis index, whereas barley root rhizodeposits decreased soil water retention and the hysteresis effect. The impact of exudates and mucilages on soil water retention almost ceased when approaching wilting point at −1500 kPa matric potential.Conclusions: Barley rhizodeposits behaved as surfactants, drying the rhizosphere at smaller suctions. Chia seed mucilage and maize root rhizodeposits behaved as hydrogels that hold more water in the rhizosphere, but with slower rewetting and greater hysteresis

Significance of root hairs for plant performance under contrasting field conditions and water deficit

Background and Aims Previous laboratory studies have suggested selection for root hair traits in future crop breeding to improve resource use efficiency and stress tolerance. However, data on the interplay between root hairs and open-field systems, under contrasting soils and climate conditions, are limited. As such, this study aims to experimentally elucidate some of the impacts that root hairs have on plant performance on a field scale. Methods A field experiment was set up in Scotland for two consecutive years, under contrasting climate conditions and different soil textures (i.e. clay loam vs. sandy loam). Five barley (Hordeum vulgare) genotypes exhibiting variation in root hair length and density were used in the study. Root hair length, density and rhizosheath weight were measured at several growth stages, as well as shoot biomass, plant water status, shoot phosphorus (P) accumulation and grain yield. Key Results Measurements of root hair density, length and its correlation with rhizosheath weight highlighted trait robustness in the field under variable environmental conditions, although significant variations were found between soil textures as the growing season progressed. Root hairs did not confer a notable advantage to barley under optimal conditions, but under soil water deficit root hairs enhanced plant water status and stress tolerance resulting in a less negative leaf water potential and lower leaf abscisic acid concentration, while promoting shoot P accumulation. Furthermore, the presence of root hairs did not decrease yield under optimal conditions, while root hairs enhanced yield stability under drought. Conclusions Selecting for beneficial root hair traits can enhance yield stability without diminishing yield potential, overcoming the breeder’s dilemma of trying to simultaneously enhance both productivity and resilience. Therefore, the maintenance or enhancement of root hairs can represent a key trait for breeding the next generation of crops for improved drought tolerance in relation to climate change

Rhizosphere-scale quantification of hydraulic and mechanical properties of soil impacted by root and seed exudates

Using rhizosphere-scale physical measurements we test the hypothesis that plant exudates gel together soil particles and on drying they enhance soil water repellency. Barley and maize root exudates were compared with chia seed exudate, a commonly used root exudate analogue. Sandy loam and clay loam soils were treated with root exudates at 0.46 and 4.6 mg exudate g-1 dry soil, and chia seed exudate at 0.046, 0.46, 0.92, 2.3 and 4.6 mg exudate g-1 dry soil. Soil hardness and modulus of elasticity were measured at -10 kPa matric potential using a 3 mm diameter spherical indenter. Water sorptivity and repellency index of air-dry soil were measured using a miniaturized infiltrometer device with a 1 mm tip radius. Soil hardness increased by 28% for barley root exudate, 62% for maize root exudate, and 86% for chia seed exudate at 4.6 mg g-1 concentration for sandy loam soil. For a clay loam soil, root exudates did not affect soil hardness, whereas chia seed exudate increased soil hardness by 48% at 4.6 mg g-1concentration. Soil water repellency increased by 48% for chia seed exudate and 23% for maize root exudate, but not for barley root exudate at 4.6 mg g-1 concentration for sandy loam soil. For clay loam soil, chia seed exudate increased water repellency by 45%, whereas root exudates did not affect water repellency at 4.6 mg g-1concentration. Water sorptivity and repellency were both correlated with hardness, presumably due to the combined influence of exudates on hydrological and mechanical properties of soils

HuB (elavl2) mRNA Is Restricted to the Germ Cells by Post-Transcriptional Mechanisms including Stabilisation of the Message by DAZL

The ability of germ cells to carry out a gene regulatory program distinct from the surrounding somatic tissue, and their capacity to specify an entire new organism has made them a focus of many studies that seek to understand how specific regulatory mechanisms, particularly post-transcriptional mechanisms, contribute to cell fate. In zebrafish, germ cells are specified through the inheritance of cytoplasmic determinants, termed the germ plasm, which contains a number of maternal mRNAs and proteins. Investigation of several of these messages has revealed that the restricted localisation of these mRNAs to the germ plasm and subsequent germ cells is due to cis-acting sequence elements present in their 3′UTRs. Here we show that a member of the Hu family of RNA-binding proteins, HuB, is maternally provided in the zebrafish embryo and exhibits germ cell specific expression during embryogenesis. Restriction of HuB mRNA to the germ cells is dependent on a number of sequence elements in its 3′UTR, which act to degrade the mRNA in the soma and stabilise it in the germ cells. In addition, we show that the germ cell specific RNA-binding protein DAZL is able to promote HuB mRNA stability and translation in germ cells, and further demonstrate that these activities require a 30 nucleotide element in the 3′UTR. Our study suggests that DAZL specifically binds the HuB 3′UTR and protects the message from degradation and/or enhances HuB translation, leading to the germ cell specific expression of HuB protein

Rare and Frequent Promoter Methylation, Respectively, of TSHZ2 and 3 Genes That Are Both Downregulated in Expression in Breast and Prostate Cancers

Neoplastic cells harbor both hypomethylated and hypermethylated regions of DNA. Whereas hypomethylation is found mainly in repeat sequences, regional hypermethylation has been linked to the transcriptional silencing of certain tumor suppressor genes. We attempted to search for candidate genes involved in breast/prostate carcinogenesis, using the criteria that they should be expressed in primary cultures of normal breast/prostate epithelial cells but are frequently downregulated in breast/prostate cancer cell lines and that their promoters are hypermethylated.We identified several dozens of candidates among 194 homeobox and related genes using Systematic Multiplex RT-PCR and among 23,000 known genes and 23,000 other expressed sequences in the human genome by DNA microarray hybridization. An additional examination, by real-time qRT-PCR of clinical specimens of breast cancer, further narrowed the list of the candidates. Among them, the most frequently downregulated genes in tumors were NP_775756 and ZNF537, from the homeobox gene search and the genome-wide search, respectively. To our surprise, we later discovered that these genes belong to the same gene family, the 3-member Teashirt family, bearing the new names of TSHZ2 and TSHZ3. We subsequently determined the methylation status of their gene promoters. The TSHZ3 gene promoter was found to be methylated in all the breast/prostate cancer cell lines and some of the breast cancer clinical specimens analyzed. The TSHZ2 gene promoter, on the other hand, was unmethylated except for the MDA-MB-231 breast cancer cell line. The TSHZ1 gene was always expressed, and its promoter was unmethylated in all cases.TSHZ2 and TSHZ3 genes turned out to be the most interesting candidates for novel tumor suppressor genes. Expression of both genes is downregulated. However, differential promoter methylation suggests the existence of distinctive mechanisms of transcriptional inactivation for these genes

Restoration of contact inhibition in human glioblastoma cell lines after MIF knockdown

<p>Abstract</p> <p>Background</p> <p>Studies of the role of the cytokine macrophage-migration-inhibitory-factor (MIF) in malignant tumors have revealed its stimulating influence on cell-cycle progression, angiogenesis and anti-apoptosis.</p> <p>Results</p> <p>Here we show that <it>in vitro </it>targeting MIF in cultures of human malignant glioblastoma cells by either antisense plasmid introduction or anti-MIF antibody treatment reduced the growth rates of tumor cells. Of note is the marked decrease of proliferation under confluent and over-confluent conditions, implying a role of MIF in overcoming contact inhibition. Several proteins involved in contact inhibition including p27, p21, p53 and CEBPalpha are upregulated in the MIF antisense clones indicating a restoration of contact inhibition in the tumor cells. Correspondingly, we observed a marked increase in MIF mRNA and protein content under higher cell densities in LN18 cells. Furthermore, we showed the relevance of the enzymatic active site of MIF for the proliferation of glioblastoma cells by using the MIF-tautomerase inhibitor ISO-1.</p> <p>Conclusion</p> <p>Our study adds another puzzle stone to the role of MIF in tumor growth and progression by showing the importance of MIF for overcoming contact inhibition.</p