A more healthful, gluten-free flour made from sweet potatoes

Orange, starchy sweet potatoes are great mashed, cut into fries or just roasted whole. But you likely haven't considered grinding them into a flour and baking them into your next batch of cookies -- or at least, not yet! Recent research published in ACS Food Science & Technology has reported the best method to turn sweet potatoes into gluten-free flours that are packed with antioxidants and perfect for thickening or baking.

Wheat flour has been used for tens of thousands of years, and likely isn't going away anytime soon. But for those who face gluten intolerance or have celiac disease, the gluten proteins in wheat flour can lead to stomach pain, nausea and even intestinal damage. Several gluten-free options are either already available or in development, including those made from banana peels, almonds and various grains. But an up-and-coming contender is derived from sweet potatoes, as the hearty tuber is packed with antioxidants and nutrients, along with a slightly sweet flavor and hint of color.

Before it can become a common ingredient in store-bought baked goods, the best practices for processing the flour need to be established. Though previous studies have investigated a variety of parameters, including the way the potatoes are dried and milled, none have yet determined how these different steps could interact with one another to produce flours best suited for certain products. So, Ofelia Rouzaud-Sández and colleagues wanted to investigate how two drying temperatures and grinding processes affected the properties of orange sweet potato flour.

To create their flours, the team prepared samples of orange sweet potatoes (Ipomoea batatas) dried at either 122 or 176 F then ground them once or twice. They investigated many parameters for each sample, comparing them to store-bought sweet potato flour and a traditional wheat one. Regardless of drying temperature, grinding once damaged just enough of the starch to make it ideal for fermented products, such as gluten-free breads. Grinding twice further disrupted the starch's crystallinity, producing thickening agents ideal for porridges or sauces. When baked into a loaf of bread, the high-temperature-dried, single-ground sample featured higher antioxidant capacity than both the store-bought version and the wheat flour. The researchers say that these findings could help expand the applications for orange sweet potato flour, both for home cooks and the packaged food industry.

From Science Daily

Evolution of wheat spikes since the Neolithic revolution

Around 12,000 years ago, the Neolithic revolution radically changed the economy, diet and structure of the first human societies in the Fertile Crescent of the Near East. With the beginning of the cultivation of cereals -- such as wheat and barley -- and the domestication of animals, the first cities emerged in a new social context marked by a productive economy. Now, a study published in the journal Trends in Plant Science and co-led by the University of Barcelona, the Agrotecnio centre and the University of Lleida, analyses the evolution of wheat spikes since its cultivation began by the inhabitants of ancient Mesopotamia -- the cradle of agriculture in the world -- between the Tigris and the Euphrates.

The authors of the study are Rut Sánchez-Bragado and Josep Lluís Araus-Ortega, from the UB Faculty of Biology and Agrotecnio-UdL; Gustavo A. Slafer, ICREA researcher at the UdL School of Agrifood and Forestry Science and Engineering, and Gemma Molero, from the International Maize and Wheat Improvement Center in Mexico, currently a researcher at KWS Seeds Inc.

A cereal that changed human history

The cultivation of wheat -- a grass that became basic food -- represented a turning point in the progress of human civilisation. Today it is the world's most important crop in terms of food security, but EU data warn that the impact of climate change could significantly increase its price and modify its production process in certain areas of the world.

Throughout the domestication process of wheat, the plant phenotype has undergone both rapid (within a few hundred years) and slow (thousands of years) changes, such as the weakening of the rachis, the increase in seed size, and the reduction or disappearance of the awns. In particular, awned and awnless wheat varieties are found all over the world, although the latter tend to be abundant in regions with arid climates, especially during the final stages of cultivation in late spring, a condition typical of Mediterranean environments.

"It is important to conduct studies that show which wheat varieties are best adapted to different environmental growing conditions, especially in a context of climate change. Studying the past retrospectively can give us an idea of the evolution of wheat cultivation over the millennia since agriculture appeared in ancient Mesopotamia," says Rut Sánchez-Bragado, first author of the study, who got a PhD at the UB.

"Awns are organs of the spike that have traditionally been associated with the plant's adaptations to drought conditions," says Josep Lluís Araus, professor at the Department of Evolutionary Biology, Ecology and Environmental Sciences of the Faculty of Biology.

"However, archaeological and historical records show that the wheat spike has existed predominantly with awns for more than ten millennia after the domestication of wheat. It is not until the last millennium that evidence shows in many cases the absence of awns, indicating a selection by farmers -- probably in an undirected way -- against this organ," stresses Araus, one of the most cited authors in the world according to Clarivate Analytics' Highly Cited Researchers (2022).

"The role of wheat awns in their performance remains controversial despite decades of studies," says researcher Gustavo A. Slafer, corresponding author of the study.

Spike awns: beneficial for the plant?

Is the presence of awns on the spike beneficial for the plant and the crops? Although there is no scientific consensus, "everything suggests that in conditions where the plant does not suffer from water stress, the extra photosynthetic capacity of the awns does not compensate for other potential negative effects (reduced susceptibility to fungal diseases, limitation in the total number of large ones that an ear supports, etc.)," says Araus.

"However, in wetter climates the awns accumulate moisture and can promote the spread of diseases," says Rut Sánchez-Bragado. "So, as the world's population is continuously growing, it is necessary to investigate the role of the awned spikes in the changing conditions of our climate in order to meet the world's demand for a primary food commodity such as wheat."

Read more at Science Daily

Thirsty wheat needed new water management strategy in ancient China

Research from Washington University in St. Louis shows that a practice of purposeful water management, or irrigation, was adopted in northern China about 4,000 years ago as part of an effort to grow new grains that had been introduced from southwest Asia.

But the story gets more complex from there. Wheat and barley arrived on the scene at about the same time, but early farmers only used water management techniques for wheat. The results, reported Nov. 9 in the journal Antiquity, raise awareness that the dispersal of domesticated crops and the knowledge of best using them can be traced independently across time and space.

"Pioneering farmers who cultivated wheat in this region managed water to meet the higher demand of this newly introduced grain," said Xinyi Liu, an associate professor of archaeology in Arts & Sciences, who collaborated on this study with researchers from several prominent institutions in China and Australia, including Guanghui Dong from Lanzhou University, who led the field expedition on the Loess Plateau. "The water management may have been achieved either by deliberate watering or by strategic planting in soils with higher water retention."

On the other hand, early farmers were able to grow the other new grain, barley, in a rainfed system as if it were just another kind of millet -- the locally domesticated and most commonly grown grain in northern China at the time -- without using any form of irrigation.

Liu published the study with Washington University graduate student Yufeng Sun. Other co-authors include Haiming Li and Petra Vaiglova, former members of Liu's lab group.

Introducing irrigation

Both wheat and barley were domesticated in an area known to archaeologists as the hilly flanks of the Fertile Crescent in southwest Asia, where they originally were grown as winter crops. Traditionally, farmers there sowed their seeds in autumn -- to avoid the summer drought period -- and harvested them in late spring or early summer before the next drought season.

When these Fertile Crescent crops, wheat and barley, were introduced to East Asia about 4,000 years ago, they would have encountered a markedly different climate compared with where they originated.

"Every summer, the East Asian monsoon brings rains from the Pacific Ocean to a region otherwise arid throughout the rest of the year. This environment is perfect for rainfed millet cultivation as these local grains are drought tolerant but need considerable water in the summer growing season," Liu said. "But it is a different story if you try to grow wheat there, not only because it is water demanding, but also the growing cycle doesn't match the rainy season."

Liu and his colleagues wanted to know: Did the farmers who sought to grow the new grains in northern China also introduce new systems of irrigation to support them?

"The introduction of a new irrigation system is something that scholars have speculated about, but now we have the technology to seek direct evidence," Liu said.

Using relatively new techniques, the actual growing conditions of past crops -- including past water and soil conditions during plant growth -- can be measured using the stable carbon and nitrogen isotope compositions of charred plant remains. These methods initially were established in plant science for research concerning environmental conditions of modern-day agriculture and have been subsequently applied to archaeological research.

Previous studies using similar approaches have shed significant light on early crop management in Europe and the Middle East. This research is one of the first attempts to apply it to East Asian monsoon environments with innovative questions.

For this study, the scientists identified more than 35,000 charred seed remains of cereal plants, including wheat, barley and millet, from more than 50 archaeological sites excavated on the Loess Plateau of China spanning a timeframe over eight millennia. Selected plant remains from this collection were radiocarbon dated and isotopically measured.

The results showed major differences between wheat and barley.

Despite the arid local environment, the majority of the wheat samples from all time periods had isotopic values above an optimal watering threshold, indicating that their growth was not limited by water availability.

"We see this in the Qijia culture period, when wheat and barley were just introduced to this region," Liu said. "The isotopic data of wheat show a significant level of water manipulation unambiguously since 4,000 years ago, indicating the new crop was introduced with water management strategies to support it."

Simple ditches can be powerful

This evidence alone does not necessarily imply large-scale irrigation, Liu is quick to point out; instead, wheat crops may have been strategically sown in areas with the best water availability, either close to local springs or in soils with high water retention.

"In those locations, small ditches to diffuse water is sufficient," Liu said. "This explains why there is no archaeological evidence of channels or other irrigation installations in the area until much later."

Barley, on the other hand, appears to have been grown on the dry hills of the Loess Plateau without a special water management approach -- a landscape and cultivation strategy that had been familiar to the Neolithic millet farmers since 8,000 years ago.

This and other evidence suggest to Liu and his collaborators that ancient farmers sought to optimize land use and crop yield by taking advantage of the different water demands of these two crops.

"Our results raise an awareness that the dispersal of domesticated crops and the knowledge of best using them can be traced independently across time and space," Liu said.

"Central to our inquiry is the tension between non-native crops and indigenous farming practices," he said. "When non-native innovations were adopted in another cultural and physical environment, they would have been transformed within the local context. How this happens is an enduring question that is relevant to globalization in the past and present."

This study resonates with other archaeological investigations led by Liu's research group, the Laboratory for the Analysis of Early Food-Webs at Washington University. For example, co-author Sun's previous work with Washington University graduate student Melissa Ritchey demonstrated a similar geographic decoupling of the dispersal of grains and cuisines, such that wheat and barley dispersed into ancient China 4,000 years ago, but the western grinding-and-baking cuisines did not. The eastern movement of these grains involved selections of phenotypic traits adapted to ancient China's cooking tradition of using steaming-and-boiling.

It has been a long time since some scholars assumed the association between the origin of bureaucracy and irrigation, and ancient China had been used as an example of "oriental despotism," according to Liu. The "hydraulic empire" hypothesis speculated that a centralized government structure that maintained power would have been derived from the need for flood control and irrigation.

Read more at Science Daily

Growing cereal crops with less fertilizer

Researchers at the University of California, Davis, have found a way to reduce the amount of nitrogen fertilizers needed to grow cereal crops. The discovery could save farmers in the United States billions of dollars annually in fertilizer costs while also benefiting the environment.

The research comes out of the lab of Eduardo Blumwald, a distinguished professor of plant sciences, who has found a new pathway for cereals to capture the nitrogen they need to grow.

The discovery could also help the environment by reducing nitrogen pollution, which can lead to contaminated water resources, increased greenhouse gas emissions and human health issues. The study was published in the journal Plant Biotechnology.

Nitrogen is key to plant growth, and agricultural operations depend on chemical fertilizers to increase productivity. But much of what is applied is lost, leaching into soils and groundwater. Blumwald's research could create a sustainable alternative.

"Nitrogen fertilizers are very, very expensive," Blumwald said. "Anything you can do to eliminate that cost is important. The problem is money on one side, but there are also the harmful effects of nitrogen on the environment."

A new pathway to natural fertilizer

Blumwald's research centers on increasing the conversion of nitrogen gas in the air into ammonium by soil bacteria -- a process known as nitrogen fixation.

Legumes such as peanuts and soybeans have root nodules that can use nitrogen-fixing bacteria to provide ammonium to the plants. Cereal plants like rice and wheat don't have that capability and must rely on taking in inorganic nitrogen, such as ammonia and nitrate, from fertilizers in the soil.

"If a plant can produce chemicals that make soil bacteria fix atmospheric nitrogen gas, we could modify the plants to produce more of these chemicals," Blumwald said. "These chemicals will induce soil bacterial nitrogen fixation and the plants will use the ammonium formed, reducing the amount of fertilizer used."

Blumwald's team used chemical screening and genomics to identify compounds in rice plants that enhanced the nitrogen-fixing activity of the bacteria.

Then they identified the pathways generating the chemicals and used gene editing technology to increase the production of compounds that stimulated the formation of biofilms. Those biofilms contain bacteria that enhanced nitrogen conversion. As a result, nitrogen-fixing activity of the bacteria increased, as did the amount of ammonium in the soil for the plants.

"Plants are incredible chemical factories," he said. "What this could do is provide a sustainable alternative agricultural practice that reduces the use of excessive nitrogen fertilizers."

The pathway could also be used by other plants. A patent application on the technique has been filed by the University of California and is pending.

Read more at Science Daily

How bread wheat got its gluten: Tracing the impact of a long-lost relative on modern bread wheat

Genetic detective work has uncovered an obscure ancestor of modern bread wheat, in a finding similar to uncovering a famous long-lost relative through DNA analysis in humans.

In a study which appears in Nature Biotechnology researchers sequenced the DNA from 242 unique accessions of Aegilops tauschii gathered over decades from across its native range -- from Turkey to Central Asia.

Population genome analysis led by Dr Kumar Gaurav from the John Innes Centre revealed the existence of a distinct lineage of Aegilops tauschii restricted to present day Georgia, in the Caucuses region -- some 500 kilometers from the Fertile Crescent where wheat was first cultivated -- an area stretching across modern-day Iraq, Syria, Lebanon, Palestine, Israel, Jordan, and Egypt.

First author of the study in Nature Biotechnology, Dr Kumar Gaurav said, "The discovery of this previously unknown contribution to the bread wheat genome is akin to discovering the introgression of Neanderthal DNA into the out of Africa human genome,"

"It is most likely to have occurred though a hybridization outside the Fertile Crescent. This group of Georgian accessions form a distinct lineage that contributed to the wheat genome by leaving a footprint in the DNA."

The discovery comes via a major international collaboration to improve crops by exploring useful genetic diversity in Aegilops tauschii, awild relative of bread wheat. The Open Wild Wheat Consortium brought together 38 research groups and researchers from 17 countries.

Further research by Dr Jesse Poland's group at Kansas State University was published in a companion paper in Communications Biology and shows that the ancestral Aegilops tauschii DNA found in modern bread wheat includes the gene that gives superior strength and elasticity to dough.

Dr. Poland said, "We were amazed to discover that this lineage has provided the best-known gene for superior dough quality."

The researchers speculate that the newly discovered lineage may have been more geographically widespread in the past, and that it may have become separated as a refugium population during the last ice-age.

Reflecting on all that has come together to make this work possible, Dr Brande Wulff, corresponding author of the study, remarked, "Fifty or sixty years ago at a time when we barely understood DNA, my scientific forebears were traversing the Zagros mountains in the middle east and Syria and Iraq. They were collecting seeds, perhaps having an inkling that one day these could be used for improving wheat. Now we are so close to unlocking that potential, and for me that is extraordinarily exciting."

Deciphering Wheat's Complex Genome

Modern "hexaploid" wheat, is a complex genetic combination of different grasses with a huge genetic code, split into A, B and D sub-genomes. Hexaploid wheat accounts for 95 percent of all cultivated wheat. Hexaploid means that the DNA contains six sets of chromosomes -- three pairs of each.

Through a combination of natural hybridizations and human cultivation, Aegilops tauschii provided the D-genome to modern wheat. The D-genome added the properties for making dough, and enabled bread wheat to flourish in different climates and soils.

The origin of modern hexaploid bread wheat has long been the subject of intense scrutiny with archeological and genetic evidence suggesting that the first wheat was cultivated 10,000 years ago in the Fertile Crescent.

Domestication, while increasing yield and increasing agronomic performance, came at the cost of a pronounced genetic bottleneck eroding genetic diversity for protective traits to be found in Aegilops tauschii such as disease resistance and heat tolerance.

Analysis performed by Dr. Gaurav and the research team revealed that just 25% of the genetic diversity present in Aegilops tauschii made it into hexaploid wheat. To explore this diversity in the wild gene pool, they used a technique called association mapping to discover new candidate genes for disease and pest resistance, yield and environmental resilience.

Dr. Sanu Arora, who had earlier led a study to clone disease resistance genes from Aegilops tauschii said, "Previously we were restricted to exploring a very small subset of the genome for disease resistance, but in the current study, we have generated data and techniques to undertake an unbiased exploration of the species diversity."

Further experiments demonstrated the transfer of candidate genes for a subset of these traits into wheat using genetic transformation and conventional crossing -- facilitated by a library of synthetic wheats -- specially bred material which incorporates Aegilops tauschii genomes.

This publicly available library of synthetic wheats captures 70 per cent of the diversity present across all three known Aegilops tauschii lineages, enabling researchers to assess traits rapidly in a background of hexaploid wheats.

"Our study provides an end-to-end pipeline for rapid and systematic exploration of the Aegilops tauschii gene pool for improving modern bread wheat." says Dr Wulff.

Read more at Science Daily