Plant hormones associated with increasing grain number and yield potential in wheat (Triticum aestivum L.) and their genetic regulation

Plant hormones are organic substances that influence specific physiological processes, such as floret fertility, and move throughout the plant. Previous studies suggest that genetic variation in grain number in cereals is associated with hormones such as cytokinin, which is crucial in controlling cell division and lateral meristem activity. This has been demonstrated in cereals when QTLs linked with reduced expression of cytokinin oxidase/dehydrogenase (OsCKX2) increased grain number in rice and wheat. However, how hormones regulate grain number traits such as fruiting efficiency (FE, ratio of grain number to spike dry weight at anthesis) and grain dry matter partitioning in wheat is not fully understood. The objectives of this study were, using a high biomass spring wheat panel, to identify novel grain number and partitioning traits for advancing harvest index and grain yield, and to determine how they are influenced by spike hormones. Finally, to understand the genetic regulation of these traits, using a bespoke target sequence capture strategy, to generate SNPs and establish molecular markers for the hormonal traits. A high biomass association panel (HiBAP II) of 150 CIMMYT spring wheat genotypes was phenotyped for grain number and partitioning traits in the field under irrigated conditions and spike hormone levels were sampled at anthesis in two seasons in NW Mexico. A subset of 10 genotypes representative of field variation for FE was grown in the glasshouse under well-watered conditions at the University of Nottingham, UK in three years for detailed hormonal analysis at GS49 (late booting) and 65 (anthesis). To test if certain plant components and stem internodes were competing with the spike at GS49 and GS65, destructive samples were taken where the plants were separated into their constitutive parts. Results showed genetic variation in grain yield correlated with grain number in both the glasshouse and field experiments, and grain yield correlated with harvest index in the field experiments. The increase in grain number amongst genotypes was associated with an increase in FE. The stem internode traits which were competing for most with spike growth was stem internode 2 leaf sheath, suggesting reducing internode 2 leaf sheath length could increase allocation of assimilates to the spike at anthesis. The results also identified novel genetic variation in spike hormones and found associations between higher levels of cytokinins and increases in grain number and yield at both GS49 and GS65 in the glasshouse and field experiments. The genetic variation in spike cytokinins also correlated across the glasshouse and field experiments. Twenty-six traits were analysed in a genome-wide association study and 213 putative marker-trait associations were identified, while 53 candidate genes were suggested including one candidate gene on chromosome 1B for spike cytokinins zeatin riboside and isopentenyladenosine at anthesis, which, in Arabidopsis, codes for an auxin efflux carrier protein PIN3 that is regulated by cytokinins. The next steps include validating the markers through developing KASP markers to be deployed in wider germplasm and using the genetic information from this study to improve traits in plant breeding programmes

Video Summary of How Credible is Online Physical Activity Advice? The Accuracy of Free Adult Educational Materials

The uploaded work is a video summary of original research. The video is less than seven minutes long. The original research summarized in the video examined the credibility of physical activity advice presented in online educational materials for lay adults. The video highlights main points of the research, leads the viewer through steps to judge the credibility of lay material, and provides links to resources for further education and guidance. The video has several supplemental files. They are as follows: (a) the full transcript text to the video narration, which includes the links to the resource material that are listed at the end of the video, (b) a copy of the video summary for free download, and (c) a copy of the closed-captioning file with English subtitles. In conclusion, the uploaded video summary and its supplemental files are for use in a variety of educational settings, serving students and professionals

JC Virus infected choroid plexus epithelial cells produce extracellular vesicles that infect glial cells independently of the virus attachment receptor

The human polyomavirus, JCPyV, is the causative agent of progressive multifocal leukoencephalopathy (PML) in immunosuppressed and immunomodulated patients. Initial infection with JCPyV is common and the virus establishes a long-term persistent infection in the urogenital system of 50-70% of the human population worldwide. A major gap in the field is that we do not know how the virus traffics from the periphery to the brain to cause disease. Our recent discovery that human choroid plexus epithelial cells are fully susceptible to virus infection together with reports of JCPyV infection of choroid plexus in vivo has led us to hypothesize that the choroid plexus plays a fundamental role in this process. The choroid plexus is known to relay information between the blood and the brain by the release of extracellular vesicles. This is particularly important because human macroglia (oligodendrocytes and astrocytes), the major targets of virus infection in the central nervous system (CNS), do not express the known attachment receptors for the virus and do not bind virus in human tissue sections. In this report we show that JCPyV infected choroid plexus epithelial cells produce extracellular vesicles that contain JCPyV and readily transmit the infection to human glial cells. Transmission of the virus by extracellular vesicles is independent of the known virus attachment receptors and is not neutralized by antisera directed at the virus. We also show that extracellular vesicles containing virus are taken into target glial cells by both clathrin dependent endocytosis and macropinocytosis. Our data support the hypothesis that the choroid plexus plays a fundamental role in the dissemination of virus to brain parenchyma

JC Polyomavirus Uses Extracellular Vesicles To Infect Target Cells

The endemic human JC polyomavirus (JCPyV) causes progressive multifocal leukoencephalopathy in immune-suppressed patients. The mechanisms of virus infection in vivo are not understood because the major target cells for virus in the brain do not express virus receptors and do not bind virus. We found that JCPyV associates with extracellular vesicles (EVs) and can infect target cells independently of virus receptors. Virus particles were found packaged inside extracellular vesicles and attached to the outer side of vesicles. Anti-JCPyV antisera reduced infection by purified virus but had no effect on infection by EV-associated virus. Treatment of cells with the receptor-destroying enzyme neuraminidase inhibited infection with purified virus but did not inhibit infection by EV-associated virus. Mutant pseudoviruses defective in sialic acid receptor binding could not transduce cells as purified pseudovirions but could do so when associated with EVs. This alternative mechanism of infection likely plays a critical role in the dissemination and spread of JCPyV both to and within the central nervous system

Biogenesis of JC Polyomavirus Associated Extracellular Vesicles

JC polyomavirus (JCPyV) is a small, non-enveloped virus that persists in the kidney in about half the adult population. In severely immune-compromised individuals JCPyV causes the neurodegenerative disease progressive multifocal leukoencephalopathy (PML) in the brain. JCPyV has been shown to infect cells by both direct and indirect mechanisms, the latter involving extracellular vesicle (EV) mediated infection. While direct mechanisms of infection are well studied indirect EV mediated mechanisms are poorly understood. Using a combination of chemical and genetic approaches we show that several overlapping intracellular pathways are responsible for the biogenesis of virus containing EV. Here we show that targeting neutral sphingomyelinase 2 (nSMase2) with the drug cambinol decreased the spread of JCPyV over several viral life cycles. Genetic depletion of nSMase2 by either shRNA or CRISPR/Cas9 reduced EV-mediated infection. Individual knockdown of seven ESCRT-related proteins including HGS, ALIX, TSG101, VPS25, VPS20, CHMP4A, and VPS4A did not significantly reduce JCPyV associated EV (JCPyV(+) EV) infectivity, whereas knockdown of the tetraspanins CD9 and CD81 or trafficking and/or secretory autophagy-related proteins RAB8A, RAB27A, and GRASP65 all significantly reduced the spread of JCPyV and decreased EV-mediated infection. These findings point to a role for exosomes and secretory autophagosomes in the biogenesis of JCPyV associated EVs with specific roles for nSMase2, CD9, CD81, RAB8A, RAB27A, and GRASP65 proteins

Associations between endogenous spike cytokinins and grain-number traits in spring wheat genotypes

Genetic variation in grain number has been positively associated with levels of cytokinins in inflorescences in cereals, although studies quantifying endogenous levels in the field are currently lacking. The present study, using a spring wheat association mapping panel (HiBAP II) of 150 lines, quantified associations between spike hormone levels and grain number and associated traits. The HiBAP II panel was grown in the field in NW Mexico under irrigated conditions for one year and a subset of ten genotypes in the glasshouse under well-watered conditions for three years. The spike levels of four cytokinins (trans-zeatin riboside, trans-zeatin, isopentenyladenosine, and isopentenyladenine) were measured by using ultra-high-performance liquid chromatography coupled with electrospray ionization tandem mass spectrometry. In the glasshouse experiments, spike hormone levels were measured at booting and anthesis, and in the field experiment at anthesis. In the glasshouse experiments, cytokinin levels were also measured in the basal, central, and apical spikelets separately in addition to at the whole spike level. The spike cytokinin levels did not differ significantly between the basal, central and apical sections of the spike. or show a spike position × genotype interaction. In the glasshouse experiments, significant genetic variation was detected for the expression of the four cytokinins in spikes at booting. At booting, spike trans-zeatin concentration ranged amongst genotypes from 4.5 to 16.0 ng g−1 FW and was positively correlated with grain number per main shoot (r = 0.77, P < 0.05). In the field at anthesis, the spike levels of each of trans-zeatin, trans-zeatin riboside and isopentenyl adenosine were positively correlated with grains per m2 (r = 0.17–0.19, P < 0.05). Our results indicated that selection for high spike cytokinin levels in wheat germplasm offers scope to raise grain number and yield potential in wheat

Plant hormones associated with increasing grain number and yield potential in wheat (Triticum aestivum L.) and their genetic regulation

Plant hormones are organic substances that influence specific physiological processes, such as floret fertility, and move throughout the plant. Previous studies suggest that genetic variation in grain number in cereals is associated with hormones such as cytokinin, which is crucial in controlling cell division and lateral meristem activity. This has been demonstrated in cereals when QTLs linked with reduced expression of cytokinin oxidase/dehydrogenase (OsCKX2) increased grain number in rice and wheat. However, how hormones regulate grain number traits such as fruiting efficiency (FE, ratio of grain number to spike dry weight at anthesis) and grain dry matter partitioning in wheat is not fully understood. The objectives of this study were, using a high biomass spring wheat panel, to identify novel grain number and partitioning traits for advancing harvest index and grain yield, and to determine how they are influenced by spike hormones. Finally, to understand the genetic regulation of these traits, using a bespoke target sequence capture strategy, to generate SNPs and establish molecular markers for the hormonal traits. A high biomass association panel (HiBAP II) of 150 CIMMYT spring wheat genotypes was phenotyped for grain number and partitioning traits in the field under irrigated conditions and spike hormone levels were sampled at anthesis in two seasons in NW Mexico. A subset of 10 genotypes representative of field variation for FE was grown in the glasshouse under well-watered conditions at the University of Nottingham, UK in three years for detailed hormonal analysis at GS49 (late booting) and 65 (anthesis). To test if certain plant components and stem internodes were competing with the spike at GS49 and GS65, destructive samples were taken where the plants were separated into their constitutive parts. Results showed genetic variation in grain yield correlated with grain number in both the glasshouse and field experiments, and grain yield correlated with harvest index in the field experiments. The increase in grain number amongst genotypes was associated with an increase in FE. The stem internode traits which were competing for most with spike growth was stem internode 2 leaf sheath, suggesting reducing internode 2 leaf sheath length could increase allocation of assimilates to the spike at anthesis. The results also identified novel genetic variation in spike hormones and found associations between higher levels of cytokinins and increases in grain number and yield at both GS49 and GS65 in the glasshouse and field experiments. The genetic variation in spike cytokinins also correlated across the glasshouse and field experiments. Twenty-six traits were analysed in a genome-wide association study and 213 putative marker-trait associations were identified, while 53 candidate genes were suggested including one candidate gene on chromosome 1B for spike cytokinins zeatin riboside and isopentenyladenosine at anthesis, which, in Arabidopsis, codes for an auxin efflux carrier protein PIN3 that is regulated by cytokinins. The next steps include validating the markers through developing KASP markers to be deployed in wider germplasm and using the genetic information from this study to improve traits in plant breeding programmes

Understanding and Communicating Physical Activity Guidelines: Creating a Training Video for Health Care Providers

Like Das et al.’s study (2018, TJACSM), studies over the last decade or so have shown that many health care providers have low knowledge of peer-reviewed physical activity guidelines (PAGs, e.g., Barton et al., 2021, Physical Therapy in Sport; Douglas et al., 2006, BMC Public Health). One remedy may be educational videos. PURPOSE: This presentation details a process to create a short, interactive, educational video to train health care providers in how to advise clients in a manner consistent with PAGs. METHODS: Over a four-month period (January to April of 2021), the second author developed a video summarizing the results of one peer-reviewed research article, which examined the extent online material matched US. PAGs at least once on average (Thomas et al., 2020, TJACSM). Methods described in the article to judge if advice matched PAGs were used to create an interactive exercise for the video. Canva and Excel were used to visually summarize key results from the research article to elicit understanding. Editorial feedback was provided by the first and third author. An oral slideshow presentation was developed in PowerPoint and narrated using a typed transcript. The presentation slides were converted into a video using the Screencast-o-Matic recording software. A checklist based on guidelines for “distraction-free” and “plain language” presentations was used to revise the video. The first author confirmed the accuracy of all content. Feedback on the clarity and utility of the video was requested from 14 undergraduates/alumni working in the first author’s lab, using a 100% optional and anonymous online survey (64% response rate, 7-day response window). RESULTS: After several iterations (PowerPoint slides & transcript = 4, video = 2), a less than 7-minute, interactive, educational video to help train health care providers to communicate PAGs was created (see Love et al., 2021, Cal Poly Digital Commons). The video was deemed clear and useful. Its features included English subtitles, a hyperlinked transcript, an interactive exercise, a summary slide with hyperlinked resources (QR codes), and a post-video review quiz (6 questions) with tailored feedback. CONCLUSION: Videos summarizing peer-reviewed research could be a viable way to improve provider PAG knowledge and communication. Future research in this area is warranted