(Press-News.org) URBANA, Ill. - Pumpkin growers dread the tiny tan scabs that form on their fruit, each lesion a telltale sign of bacterial spot disease. The specks don't just mar the fruit's flesh, they provide entry points for rot-inducing fungus and other pathogens that can destroy pumpkins and other cucurbits from the inside out. Either way, farmers pay the price, with marketable yields reduced by as much as 90%.
Despite the disease's severity, scientists don't know much about the genetics of the pathogen that causes it; nearly all the molecular information required for accurate diagnostic testing and targeted treatments is lacking for the disease.
In a new study, University of Illinois scientists, with the help of two undergraduate students, have assembled the first complete genome for the bacteria that causes the disease, Xanthomonas cucurbitae, and identified genes that are activated during infection.
"Assembling a complete circular genome means we now have the resources to better understand what's happening in the field. We can use this information to look at how the pathogen is spreading, whether there are differences in host specificity among sub-populations or strains, or how likely it is to develop resistance to chemical controls," says Sarah Hind, assistant professor in the Department of Crop Sciences at Illinois and senior author on the Phytopathology study.
After sequencing the genome, Hind's group compared it to genomes from 12 other Xanthomonas species that cause diseases in a variety of crop plants like tomato, rice, citrus, and wheat. Surprisingly, given its penchant for creating havoc in the field, Xanthomonas cucurbitae had the smallest genome and had fewer genes known to be important for other Xanthomonas species to cause disease.
"As this pathogen lacks many of the known virulence (i.e., disease-causing) genes, we don't know exactly which genes are needed by the pathogen to infect cucurbit plants," Hind says. "It could be something we've never seen before, such as a new gene or a mechanism that evolved in this species that isn't seen in the rest of the family. That could be very exciting."
To get closer to an answer, the research team grew the bacteria in liquid media that mimicked its host environment and identified more than 400 genes whose expression was altered when the pathogen interacted with its "host." In particular, they observed increased expression of genes for enzymes related to the breakdown of plant tissues, which are key for further development of the disease.
If Hind's team can learn more about these factors and how cucurbits respond to them, there may be a way to prevent the bacteria from penetrating pumpkin fruits in the first place. "That would really save the farmers," she says. "They don't care as much when it gets on the leaves, but if it infects the fruit, they're in trouble."
Hind adds, "This project wouldn't have been possible without the contributions of some really talented undergraduate students. We love having students participate in our research. They bring a sense of enthusiasm and eagerness - as well as really creative ideas - to the lab that would be hard to generate otherwise."
Although both students graduated, see new Crop Sciences students contributing to Hind's other pumpkin projects in this video. High school and transfer students can learn more about Crop Sciences coursework online.
INFORMATION:
The article, "Genome sequencing and functional characterization of Xanthomonas cucurbitae, the causal agent of bacterial spot disease of cucurbits," is published in Phytopathology [DOI: 10.1094/PHYTO-06-20-0228-R]. Authors include Rikky Rai, Julius Pasion, Tanvi Majumdar, Cory Green, and Sarah Hind. The research was supported with USDA Hatch funds, as well as an ACES Undergraduate Research Scholarship to Tanvi Majumdar.
The Department of Crop Sciences is in the College of Agricultural, Consumer and Environmental Sciences at the University of Illinois at Urbana-Champaign.
Cambridge, MA - Astronomers have now obtained a new view of the supermassive black hole at the center of galaxy M87. Images released today by the Event Horizon Telescope (EHT) collaboration reveal how the black hole, some 55 million light-years away, appears in polarized light.
The image marks the first time astronomers have captured and mapped polarization, a sign of magnetic fields, so close to the edge of a black hole.
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Now, Johns Hopkins Medicine researchers have tried to rectify that inequity, taking one of the first looks at how people who are immunocompromised respond to their first dose of one of the two mRNA vaccines -- Moderna and Pfizer-BioNTech -- currently being administered worldwide. Their findings, as published March 15, 2021, in a research letter in the END ...
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On Dec. 4, 2020, an announcement about anticipated vaccine availability was emailed to all 23,784 Geisinger employees. Recipients were asked to indicate their intention to receive a vaccine when one was available to them and the reasons for any hesitation they might have. More than two-thirds of employees responded to the survey.
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The study, by researchers affiliated with the Annenberg Public Policy Center (APPC) of the University of Pennsylvania and the University of Illinois, tested the effects of messages about vaccination in televised news reports. These included video clips of Dr. Anthony Fauci, director of the U.S. National Institute of Allergy and Infectious Diseases, talking about evidence supporting the value and safety of the MMR (measles, mumps and rubella) vaccine, and a mother who's refusing to vaccinate ...
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WASHINGTON--Residents of South Asia already periodically experience heat waves at the current level of warming. But a new study projecting the amount of heat stress residents of the region will experience in the future finds with 2 degrees Celsius of warming, the population's exposure to heat stress will nearly triple.
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With ...
An old technique flexes its muscles
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Family-centered prevention programs that foster protective caregiving can buffer the negative effects of racial discrimination on young Black people, according to a study published by University of Georgia researchers.
Research shows that Black youth exposed to various levels of racial discrimination--including slurs, threats and false accusations--are at a high risk for poor mental health outcomes such as hopelessness, conduct problems, drug use and depression. After participating in family-oriented programs, high school-age adolescents who encountered high levels of racial discrimination and received supportive caregiving evinced fewer increases in conduct problems and depression/anxiety symptoms two years later.
"This research shows that ...
