Whole genome duplication (WGD) is a common mutation in plants with profound evolutionary potential. While it is well-known that an increase in genetic material can lead to larger cell sizes, the impact of gene dosage multiplication on the metabolome remains largely unexplored.

Researchers from the VIB-UGent Center for Plant Systems Biology have now studied this impact in greater duckweed, Spirodela polyrhiza. Their results are published in the American Journal of Botany.

Genetic mutations are fundamental to adaptation and evolution. Whole genome duplication (WGD) is one of the most spectacular changes, though relatively common in plant evolutionary history. WGD results in much more than just an increase in gene numbers. The duplication of entire sets of interacting genes significantly affects dosage-sensitive pathways, offering vast potential for metabolomic diversity by increasing the gene “products” available.

Metabolites, the direct products of cellular metabolism, are crucial links between the genotype and complex phenotypes. They play roles in numerous biotic and abiotic interactions, such as gamete production, pollinator attraction, wound repair, structural support, and protection against environmental stresses like salt, drought, and UV radiation.

Throughout evolution, a conserved set of primary metabolites and hormones has been essential for plant growth and development. Given their diverse functions, metabolomic changes and novelties hold high evolutionary potential. However, the impact of polyploidization on these metabolomic changes remains largely unknown.

“The immediate effects of polyploidy are poorly understood. Theoretical explanations for immediate WGD-induced metabolomic change are almost exclusively focused on the increase in gene dosage. It is challenging to align theoretical expectations—normalized per cell—with empirical data, normalized per dry mass.

“Bridging this gap between theory and observations will lead to a better understanding of the immediate phytochemical effects of WGD,” says study leader Yves Van de Peer.

The team used discovery metabolomics to investigate the immediate effects of WGD on the metabolome of greater duckweed, Spirodela polyrhiza. Previous research indicated that WGD affects cell size and cell density per unit of biomass. To clearly assess the effect of gene dosage, normalization per cell was applied, leading to the first evaluation of dosage effects per cell at the metabolome level.

The research demonstrated that the average metabolite abundance per cell increases, although there is considerable variation in the response of individual metabolites. However, this dosage effect is somewhat balanced by the inherent cell size effect of polyploidy. The researchers confirmed that WGD induces quantitative and, to a lesser extent, qualitative changes in the metabolome.

“To fully understand the immediate effects of polyploidization we need to focus more on the cell-level impacts, particularly related to cell size. Technologies like spatial transcriptomics and single-cell omics have tremendous potential to study these cell-level impacts,” says Quinten Bafort.

It’s incredibly rare to spot a great white shark in the waters around the Bahamas, but a new study published in the journal Frontiers in Marine Science shows they visit the area more often than people realize.

A team of researchers studied acoustic tracking data, finding that at least 10 tagged white sharks made deep-water, nighttime visits during a five-year period.

“Just because they’re not being seen, doesn’t mean they’re not there,” said Simon Dedman, FIU marine scientist and co-author of the study. “Human activity and white shark habitat may simply not overlap, with white sharks visiting deeper reef waters at night as they migrate through the area.”

The white shark is an iconic apex predator, playing an important ecological role across its range. While persistent bycatch and overfishing led to white shark declines, recent studies show evidence of regional recovery of populations in the northwest Atlantic Ocean.

Southeast Florida and the Gulf of Mexico serve as important overwintering grounds for maturing white sharks. Despite the Bahamas’ proximity to Florida, only one sighting of a white shark was found in a comprehensive survey of sightings and captures from 1800 to 2010.

Researchers studied acoustic tracking data, detecting the 10 white sharks from 2020 to 2024 along the western edge of the Tongue of the Ocean, a deep-water basin off Central Andros Island. The white sharks were detected along the drop-off zone of the reef at a depth of about 25 meters, exclusively between dusk and dawn.

Seven of the 10 great white sharks were detected once, while the other three were detected across multiple days. The sharks were originally tagged off the coast of the United States and Canada, and were detected around the Bahamas during winter and spring months. The data suggests transient behavior with the sharks just passing through, according to the scientists.

The Bahamas has banned commercial longlining and gillnetting since 1993 and declared its waters a shark sanctuary in 2011. These efforts have made the Bahamas an important refuge for a variety of shark species, but data gaps exist for white sharks. These new research findings expand knowledge of white shark distribution off the Atlantic coast and highlight the importance of collaborative protective measures for species recovery.

Papaya farmers in Kenya are turning to a novel solution to combat the devastating papaya mealybug pest—parasitic wasps.

The mealybug, native to Central America, is a rapidly spreading crop pest that has been wreaking havoc on papaya crops in Kenya since 2015, causing significant economic losses for smallholder farmers.

Dorcus Lekesio, a smallholder farmer from Baringo county, has been a papaya farmer for more than 15 years. She depends on it to feed her family and educate her children.

“Papaya farming is my main source of income … my livelihood depends on it,” she says.

She says the mealybug infestation reduced her expected harvest by over half in the last year.

“We used many chemicals to spray the plants, but it has not been working,” she adds.

Alfred Bolo, another papaya smallholder from Kwale, in coastal Kenya, encountered the mealybugs on his farm in January last year.

He says he used pesticides, but they only provided temporary relief.

“I was very annoyed … I used to crush them with [my] bare hands because they were really annoying me,” he says.

Bolo then attended a farmers’ workshop convened by the County Government of Kwale, Kenya, in partnership with the agricultural research organization CABI (SciDev.Net’s parent organization), where he learned about the papaya mealybug.

“I was surprised to learn that the pest was not only affecting me, but also many other farmers in the region,” he says.

Losses

The mealybug pest is native to Central America.

In Africa, it was first reported in Ghana. It is believed to have invaded East Africa between 2015 and 2020, causing severe losses to smallholder farmers. CABI estimates that in East Africa the pest is responsible for destroying 57–91% of crops and costing farmers £2,224 (US$ 2,854) per hectare every year.

In 2019, scientists from CABI, along with the Kenya Plant Health Inspectorate Service, Kenya Agricultural and Livestock Research Organization, and Kenyatta University, identified the wasp, Acerophagus papaya, as a prospective candidate for biological control.

They say it offers a natural and safe solution to the problem of papaya mealybug.

The Kenya Agricultural and Livestock Research Organization then imported Acerophagus papayae, a parasitic wasp from Ghana, and introduced it on Bolo’s farm in March, 2023.

“It took about one month for the parasitoids to spread around the farm. They did not eliminate the mealybug but controlled their numbers to the extent that they could not cause economic losses to me,” Bolo told SciDev.Net.

He has since increased his plant production and saved on pesticide costs. “I am now harvesting about 400kgs per week, which is a good harvest.”

Selpha Miller, Post-doctoral research fellow, based at CABI, says the Kenya Standing Technical Committee on Imports and Exports gave CABI and its implementing partners, The Kenya Agricultural and Livestock Research Organization and Kenya Plant Health Inspectorate Service, an approval to release the parasitoids at the coastal counties where the pest was first reported.

Following successful management of the pest at the coast, she says, the Kenya Standing Technical Committee on Imports and Exports has approved the release in five more counties, including Baringo.

“Based from the experience at the coast, where the pest was able to be managed after six months, it is also expected it will be efficient in other regions,” Miller told SciDev.Net.

She says the parasitoid is expected to manage papaya mealybug to levels that will not cause economic damage to the farmer, “just like the parasitoid has successfully managed the pest in Ghana, where we got the parasitoid.”

“It is very safe and efficient,” she added.

Miller urges African governments to invest in classical biological control of papaya mealybug using the parasitoid.

“Papaya mealybug is a very devastating pest that can lead to huge crop losses if not controlled,” she said.

Resistance

One challenge is the potential development of resistance by the mealybug to the parasitic wasp.

“We need to monitor the situation closely to ensure that the wasp remains effective,” says Miller.

Despite these challenges, the use of Acerophagus papayae remains a promising solution to the papaya mealybug problem, according to agriculture specialists.

Vincent Abuje, Baringo county director of agriculture, tells SciDev.Net that the Acerophagus papaya is a welcome relief as the mealybug pest has caused massive losses for farmers in the county, with many not knowing how to manage it.

“Papaya farming is a major horticultural enterprise here and a source of livelihood for many households,” Abuje says.

He added that farmers tried using pesticides, but the pest would “go away but resurface after about two weeks.”

This led to frustration among farmers, who were left “staring at losses.”

Abuje said 28 agricultural extension officers were trained to advise farmers on identifying and handling the pest, and a biological control method is set to be introduced.

Abuje says he is hopeful that this will help farmers control the pest.

“We are happy and hopeful, as this has worked elsewhere, that it will help our farmers to control the destructive pest.”

Lekesio’s farm is one of those where scientists will trial parasitoids to help control the spread of papaya mealybug. “We are really praying that this works … we desperately need it to work,” she says.