Americans are growing old and, sadly, the aging process for many means more than simply turning gray or thinning hair.
According to the United States Census, in about a dozen years the number of Americans over 65 will outnumber children. Further, the Centers for Disease Control and Prevention project the number of Americans living with Alzheimer’s disease (AD) to nearly triple by 2060.
Fortunately, USDA-funded research may have found a tasty way to slow disease onset.
A study published in the American Journal of Clinical Nutrition suggests that diets high in flavonoids may protect cognitive health. Flavonoids are plant nutrients known for their antioxidant, antiviral, and anticancer properties and are found in berries, tea, dark chocolate, and other foods.
According to Jacques, who co-authored the study, about one in nine adults over age 65 are living with AD. While memory loss is the hallmark of AD, Jacques said it has many other cognitive and behavioral changes, including difficulty carrying out simple multistep activities, such as dressing or cooking; loss of judgement and attention; and changes in behavior such as depression and agitation.
Jacques’s study, one of the first truly large, long-term studies to examine the effects of flavonoids on AD, showed that diets high in certain types of flavonoids present significant promise toward preventing the onset of Alzheimer’s.
“Our study examined the association between long-term flavonoid intakes and AD over an average follow-up of 19.6 years among 2,809 participants,” he said. Results show that those who consumed the most of three types of flavonoids were more than 50 percent less likely to develop AD risks compared with those who ate the least. Plant foods, such as vegetables, fruits, berries, nuts, and seeds are good sources of flavonoids, as is a cup of green tea each day.
Age 50 is not too late to make positive dietary changes. “While the risk of dementia increases over age 70, it is now believed that its preclinical stage may predate clinical diagnosis by decades” he said. “A healthy diet during this preclinical period may provide the best opportunity for slowing the development of AD. When you approach 50, you should start thinking about a healthier diet if you haven’t already.”
According to Jacques, flavonoid-rich diets help more than just Alzheimer’s disease and related dementia.
“The bottom line is that there are many reasons to consume a healthy diet, including lower risks of cardiovascular disease and some cancers. We can now add protection of cognitive health and prevention of Alzheimer’s disease to that list.” – By Scott Elliott, USDA-ARS Office of Communications
No summer barbecue is complete without fresh watermelon. As the nation moves towards the summer grilling season, you may want to consider how watermelon’s fruit chemistry can affect your overall health. Researchers in the USDA’s Agricultural Research Service (ARS) recently identified over 1,500 small molecules of diverse chemical characters in the fruit, known as phytochemicals. They concluded that eating watermelon is an excellent way to increase your intake of antioxidants, non-protein amino acids and lycopene. This means that every time you eat watermelon, you’ll be improving the health of your cells, organs and nervous system.
The research specifically finds that the antioxidants in watermelon can help your body fight free radicals and slow down cell damage. The fruit’s non-protein amino acids will also help to repair your body tissue, break down food from other meals, and even regulate your blood pressure.
“Watermelon could be part of the refreshing and healthy fruit options on your summer picnic table,” said USDA-ARS scientist Larry Parnell. “The fruit has gone through many years of evolution, domestication, and selection for desirable qualities—mainly those associated with flesh color, texture and nutrient and sugar content. But our research continues to find that the fruit contains a wide range of nutrients that improve your overall health.”
Most Americans purchase the sweet dessert watermelon species, Citrullus lanatus, at their local grocery store or farmer’s market. This species is among the most important vegetable crops grown and consumed throughout the world, with over 100 million tons in annual global production. The fruit also has more lycopene than a raw tomato, which is linked to healthy eyes, overall heart health and protection against certain cancers. Other nutrients, like carotenoids, flavonoids, carbohydrates and alkaloids, are also found in the flesh, seed, and rind.
“I worked with Dr. Parnell and the team to develop a pioneering concept of using big data and computational biology to identify and catalog all of the phytochemicals that exist in edible fruit,” said ARS researcher Amnon Levi. “The research to identify the metabolic pathways and genome sequence of genes involved in the production of beneficial phytochemicals could be highly useful for plant scientists and breeders aiming to improve nutrient content in fruits and vegetables.”
The watermelon’s phytochemicals are human-cell-protecting compounds found in fruit, vegetables, grains and beans. All of these nutrients can contribute to your overall health in numerous ways.
Watermelon was introduced to Europe via Moorish Spain in the 10th century. Since then, watermelon has been cultivated successfully in warmer Mediterranean regions before being brought to the Americas by European colonists during the 16th century. Today, watermelon is grown in 44 U.S. states, while major production is centered in California, Florida, Georgia and Texas.
Fruits and vegetables are a part of a healthy, balanced diet, with the recommendation being 1.5 to 2 cups of fruit and 2 to 3 cups of vegetables per day.
The Agricultural Research Service is the U.S. Department of Agriculture’s chief scientific in-house research agency. Daily, ARS focuses on solutions to agricultural problems affecting America. Each dollar invested in agricultural research results in $17 of economic impact.
The rhizosphere, defined as the soil environment that surrounds the plant roots, is a rich and diverse habitat for microbes. Some members of the rhizosphere microbiome (or collection of microbes), are good, others bad while many are just there and don’t provide any benefits or harm to the host. One function of the good microbes in the rhizosphere is to help facilitate the availability and assimilation of nutrients and water from the rhizosphere. Just like the human gut, the plant rhizosphere conveys key nutritional functions and the analogy was made that “plants wear their gut on the outside”. One example is the symbiotic relationship between legumes (peas, beans) and rhizobia. Those bacteria help the plant fix atmospheric nitrogen in exchange for carbon supply. Another example is the symbiotic relationship between the plant and mycorrhizal fungi, whereby the mycorrhizae receive carbon from the plant in exchange for increased nutrient uptake (principally phosphorus and nitrogen). There is undeniable evidence that plants have developed a mechanism for recruiting good microbes to cope with environmental stress such as protection against opportunistic pathogens or drought. The rise of ‘omics’ technologies have helped profile entire microbial communities associated with plants and shed light in their biological functions. This research has fueled the development of novel commercial bioproducts to address the increasing consumer’s demand of environmentally-friendly products. As a result, there has been several commercial ‘probiotics’ and ‘prebiotics’ that have been marketed for agricultural use including many biocontrol agents such as fungal- (e.g., Trichoderma) and bacterial- based (e.g., Bacillus, Streptomyces, or Pseudomonas) bioproducts.
One goal of my research program is to identify beneficial microbes for tree and vines crops, promote practices that support the presence and abundance of beneficial microbes and figure out how good microbes help combat pathogens and support plant health. As part of a collaborative project (UC Riverside, University of Florida, USDA-ARS) funded by the California Citrus Research Board and the USDA-NIFA, we profiled the microbiome of citrus trees in the context of Huanglongbing disease (or HLB). HLB is a highly destructive and lethal disease to all commercial citrus cultivars making it a threat to citrus production globally. Finding strategies that do not only rely exclusively on management of the insect vector of the bacterium (the Asian Citrus Psyllid), is a priority to the citrus industry. In our research, we found that there were significant tissue-specific microbial shifts occurring within the citrus microbiome as trees get sicker, especially in the root compartment. As HLB progressed, there were depletions of beneficial species in roots, such as mycorrhizal fungi, and enrichments of parasitic microorganisms, such as Fusarium and Phytophthora (see Figure). HLB-affected trees decline because of the clogging the phloem sieve tubes, which limit movement of sap and translocation of sugar to the roots, hence leading to feeder root collapse. Once tree is weakened, it becomes more susceptible to pathogens such as Phytophthora which further weakens the trees and exacerbate above ground HLB symptoms. In addition, several studies from Florida suggested that cultural practices that supported root health and rhizosphere microbiome richness and diversity limited root collapse.
Figure: Citrus decline caused by HLB (https://apsjournals.apsnet.org/doi/10.1094/PBIOMES-04-20-0027- R – Ginnan et al. 2020. Phytobiomes); canopy thinning, wood dieback, feeder roots decline, collapse of beneficial microbes and enrichment of pathogens in roots.
Our group was recently awarded another research funding by the USDA-NIFA Emergency Citrus Disease Research and Extension program (project director, M.C. Roper, Microbiology and Plant Pathology, UC Riverside). This research effort in collaboration with UC Agricultural and Natural Resources, UC Davis, University of Florida, and the USDA-ARS aims at investigating the root collapse associated with HLB- impacted trees and finding ways to mitigate it by promoting root health. In the proposed work, we will test how different sectors of the root microbiome contribute to or lessen fibrous root loss and if soil amendments (e.g., humic acid treatment, mulching) and planting of HLB tolerant rootstocks (Poncirus trifoliata and P. trifoliata hybrids) can be used to mitigate root loss associated with HLB in Florida, and how tree respond to those practices under a HLB free environment in California. While these approaches will not cure trees from HLB, it will provide a science-based information for strategies that support root and tree health and sustain orchard longevity until remedies are discovered. — By Philippe Rolsausen, Professor in Cooperative Extension, UC Riverside
The Silk Road – the 4,000-mile stretch between China and western Europe where trade flourished from the second century B.C. to the 14th century A.D. – is responsible for one of our favorite and most valuable fruits: the domesticated apple.
Snack-packing travelers would pick apples at one spot, eat them and toss their cores many miles away. The seeds grew into trees in their new locations, cross-bred with the wild species and created the more than 7,000 varieties of apples that exist today.
Hybridizations with wild species have made the apple genome very complex and difficult to study, but a team of multi-disciplinary researchers – co-led by Zhangjun Fei, faculty member at the Boyce Thompson Institute, and Gan-Yuan Zhong, a scientist with the U.S. Department of Agriculture-Agricultural Research Service (USDA-ARS) in Geneva, New York – tackled this problem by applying cutting-edge sequencing technologies and bioinformatics algorithms to assemble complete sets of both chromosomes for the domesticated apple and its two main wild progenitors.
The team’s research is described in a paper published Nov. 2 in Nature Genetics, with authors from BTI, Cornell, the USDA and Shandong Academy of Agricultural Sciences.
The researchers found that the apple’s unique domestication history has led to untapped sources of genes that could be used to improve the fruit’s size, flavor, sweetness and texture.
“Plant breeders could use this detailed information to improve upon traits that matter most to consumers, which today is primarily flavor,” said Fei, also an adjunct associate professor in the College of Agriculture and Life Sciences’ School of Integrative Plant Science.
“Perhaps more importantly,” he said, “the information will help breeders produce apples that are more resistant to stress and disease.”
Fei said the new study was the outgrowth of an earlier collaboration, published in Nature Communications in 2017, which traced the history of apple domestication and evolution along the Silk Road.
Follow-up discussions among Fei, Zhong and other colleagues at Cornell inspired them to build better apple reference genomes by applying new sequencing and assembly technologies to material in USDA’s Geneva Clonal Repository, which houses the largest collection of apple accessions in the world. Many of these accessions can be traced back to the Silk Road.
In the current work, the researchers sequenced, assembled and compared the full reference genomes for three apple species: Gala, a top commercial cultivar of Malus domestica; and apple’s two main wild progenitors – the European crabapple (M. sylvestris) and the central Asian wild apple (M. sieversii), which together account for about 90% of the domesticated apple’s genome.
The results provide apple breeders with detailed genomic roadmaps that could help them build a better apple.
“We wanted to develop new genomes, especially the wild progenitors, because of the tremendous impact they could have on understanding apple’s genetic diversity and identifying useful traits for breeding new cultivars,” said Zhong.
By comparing the three genomes, the researchers were able to identify which progenitor species contributed the genes responsible for many traits in the domesticated apple.
For example, the team found that the gene giving apple its crunchy texture is located near the gene that makes it susceptible to blue mold.
“Now that we know exactly where those two genome regions are,” Fei said, “breeders could figure out a way to keep the texture gene and breed out or edit out the blue mold gene to produce a more disease-resistant cultivar.”
The team also assembled pan-genomes for the three species. A pan-genome captures all of the genetic information in a species, unlike a reference genome that captures one individual organism. Pan-genomes are especially important for a very diverse species like apple.
The team identified about 50,000 genes in the pan-genome of the domesticated apple, including about 2,000 that were not present in previously published reference genomes for apple species. “These ‘missing genes’ turn out to be really important, because many of them determine the traits of greatest interest to apple breeders,” Fei said.
Using RNA extracted from different stages of Gala fruits, they also identified genes linked to texture, aroma and other fruit characteristics that were preferentially expressed between the two copies of the genes.
“That provides us and breeders with an even deeper understanding of the genetic diversity underlying a particular trait,” Zhong said. “The findings will help our group better manage and curate more than 6,000 apple accessions in the USDA Geneva Clonal Repository, as well as enable us to provide critical genetic and genomic information associated with the accessions to breeders and other researchers.”
The team is planning on sequencing other wild apple species, which Fei said may have valuable traits that could improve stress-resistance and resilience in the domesticated apple.
The research was supported by the USDA-ARS and by the National Science Foundation. — By Michael J. Haas, Boyce Thompson Institute
California’s $86 million date industry produces more than half of the nation’s dates. Most of the fruit is grown in the arid Coachella Valley. Despite efforts by growers to conserve water, data was lacking on date palms’ actual water use to refine the best irrigation management for the crop until a recent research project led by Ali Montazar, UC Cooperative Extension irrigation and water management advisor for Imperial and Riverside counties.
New research provides data California date growers need to apply a more precise amount of irrigation water to meet the trees’ needs to produce a healthy crop (photo by Ali Montazar).
“California dates are grown in the hottest and most arid climate in North America and require substantial amounts of water in order to bring a successful crop to fruition,” Albert Keck, Coachella Valley date grower and chairman of the California Date Commission, wrote in a letter of support for this project. “In addition, there is scant modern research specifically and technically focused on growing dates in North America.”
Montazar said there is a lack of irrigation management information on date palms worldwide.
“The information developed in this study is expected to have a worldwide impact,” he said.
To determine the evapotranspiration rate and crop coefficients for California date palms, Montazar teamed up with scientists at UC Davis, California Department of Water Resources, USDA Agricultural Research Service, and USDA Salinity Laboratory.
The experiment was carried out in six date orchards in the Coachella and Imperial valleys. The sites represent various soil types and conditions, irrigation management practices, canopy characteristics, and the most common date cultivars in the region.
“The findings of the project indicate that there is considerable variability in date palm consumptive water use, both spatially and temporally,” Montazar said. In other words, the amount of water the trees use varies considerably depending on each site’s growing conditions.
He estimated the water needs for date palms planted in different soil types in the low desert region.
“Growers will be able to use the science-based information and tools developed by this project to determine their date palm water needs and optimize the efficiency of water and fertilizer use in their groves,” Montazar said.
Fruit bags protect date from insect damage and dust and prevent the fruit from falling to the ground (photo by Ali Montazar).
The peer-reviewed article “Determination of Actual Evapotranspiration and Crop Coefficients of California Date Palms Using the Residual of Energy Balance Approach” is published in the journal MDPI Waterat https://www.mdpi.com/2073-4441/12/8/2253.
“With a large quantity of new date plantings in the region, coupled with increasingly limited water resources in the Colorado River Basin Watershed, the knowledge anticipated to be developed by this research project has the potential to yield large dividends through not only improved water use efficiency, but also best management practices and crop quality,” said Keck of the California Date Commission.
Although the research focused on Coachella Valley dates, Montazar said the results are likely to be useful to growers who have orchards with similar varieties, irrigation practices, and canopy and soil features in other locations.
Montazar’s co-authors are Robert Krueger of the USDA-ARS National Clonal Germplasm Repository for Citrus and Dates; Dennis Corwin of USDA-ARS U.S. Salinity Laboratory; Alireza Pourreza UC Cooperative Extension specialist based at UC Davis Department of Biological and Agricultural Engineering; Cayle Little of California Department of Water Resources; Sonia Rios, UC Cooperative Extension advisor in Riverside County; and Richard L. Snyder UC Cooperative Extension specialist emeritus in the UC Davis Department of Land, Air and Water Resources.
The date palm irrigation project was funded by the CDFA Specialty Crop Block Grant Program. — By Pamela Kan-Rice, UCANR
USDA Agricultural Research Service (ARS) scientist and director of the Western Regional Research Center (Albany, CA), Tara McHugh and her team in the Healthy Processed Foods Research Unit are experts at solving food-manufacturing problems. Using cutting-edge processing technologies, they have helped numerous small businesses, such as Ripple Foods, turn ideas into products for the consumer.
ARS is helping Ripple Foods optimize its current pea protein drying process to make it more efficient and to further improve its products. The company manufactures its own pea protein by processing yellow split peas into a liquid form and then isolating, purifying, and drying the protein. The pea protein is then made into non-dairy milks, protein shakes, half and half, ice cream, and other products.
The drying step is necessary because producing this clean-tasting plant protein in a wet state comes with challenges: It’s difficult to transport, has a greater risk for microbial spoilage, and has handling issues, McHugh said.
“It’s also expensive to ship all over the country, so we are working to optimize the drying process—looking at a way to dehydrate it so it can be rehydrated to save expenses,” she said. “The drying process also may even improve the quality and flavor of the final product.”
Ripple Foods has a cooperative research and development agreement with ARS, which assists the company in data gathering and analysis on different aspects of its pea beverage. “Ripple’s mission is to make plant-based foods delicious,” said Aminah Johnston, a process engineer with the company. “We are always looking for ways to make our protein and products better. Our collaboration with ARS has been extremely helpful.”
This kind of research not only supports small businesses and U.S. growers, but also reduces waste and increases consumption of healthy foods.—By Sandra Avant, formerly with USDA-ARS Office of Communications.
Two of the nation’s great agricultural regions are the focus of new research that aims to head off emerging threats and improve sustainability.
Scientists with the Agricultural Research Service (ARS) are joining colleagues to create and use artificial intelligence to help farmers in the Colorado River Basin and Salinas Valley, CA, improve their management of irrigation, fertilization, and pests. USDA’s National Institute of Food and Agriculture funded the University of California, Riverside-led project with a 5-year, $10 million grant.
“This project will integrate multiple satellite and meteorological data sets to help farmers in the Southwestern United States,” said Ray Anderson, a research soil scientist with the ARS Agricultural Water Efficiency and Salinity Research Unit in Riverside. Anderson leads the ARS portion of the study, working with ARS scientists Todd Skaggs and Andrew French.
ARS has three primary roles in the project: To calculate project area crop water use and anomalies with crop water use across the entire region; develop tools that help growers avoid salinity damage while minimizing the leaching of fertilizer; and to gather field data to validate satellite algorithms.
Researchers will take advantage of advanced satellite technology to provide more frequent, detailed information to farmers than ever before. The plan is to integrate high-resolution commercial satellite data with established government satellite platforms and meteorological data.
A major advance with this work will be the use of daily, high-resolution (12-foot) satellite imagery, Anderson said. Previously, data have only been available every 1-2 weeks at 60- to 100-foot resolution and were too infrequent or coarse to provide timely and actionable information to farmers.
“By combining the new satellite data with artificial intelligence, we will be able to discover and create tools that will help farmers pinpoint areas that need better irrigation, nutrient, and pest management,” Anderson said.
“One of the major advantages to this project is that the outputs – recommendations and highlights on a smartphone app – will be accessible to all farmers,” he said. “Previously, farmers had to pay for aircraft and specialized processing to get this level of imagery and detail. Soon, high resolution satellite imagery, machine learning, and cloud processing will be available to smaller producers in one easy-to-use tool. These algorithms will help farmers with their field scouting so that they can catch problems early, before significant yield reductions occur.”
Agriculture in the Colorado River Basin and Salinas Valley employs more than 500,000 people and generates roughly $12 billion annually in revenue. Farmers in the regions grow fruits and vegetables that are shipped around the country all year round, particularly in winter.
Water availability and use top the researchers’ priority list because prolonged drought has reduced agricultural water availability in the southwestern United States.
“These valleys consume large amounts of irrigation water, but the amount and quality of irrigation water is decreasing,” Anderson said. “It is important to use existing supplies more efficiently and to protect water sources from nutrient and salinity contamination that can come from poor irrigation management.” — By Scott Elliott, USDA-ARS Office of Communications.
Dr. Ilenys Perez-Diaz (IP) is a Microbiologist with the Food Science and Market Quality and Handling Research Unit in Raleigh, NC. Her work involves research into microbes present during the fermentation and acidification of vegetables, and had some interesting things to share with the USDA-ARS in their Under the Microscope (UM) Q&A blog.
Dr. Ilenys Perez-Diaz
UM – As a microbiologist, how does your work connect to processed vegetables? What types of processes do these vegetables go through?
IP – There is a variety of microbes naturally present in fresh vegetables. The uncontrolled growth of such microbes in vegetables results in their decomposition and lack of appeal to consumers. We can control the growth of microbes in vegetables through the fermentation process, popularly known as pickles in the U.S.
I study the indigenous microorganisms in fresh vegetables and develop processes that produce fermented or acidified vegetables with prolonged shelf lives, enhanced flavor, and substantial nutritional content.
UM – What is the difference between fermentation and pickling?
IP – While these terms are used interchangeably in the USA, they are actually different. Technically, fermentation refers to the preservation of vegetables by converting the indigenous sugars to organic acids and increasing acidity. Pickling refers to vegetables that are acidified, primarily with vinegar, to extend their shelf-life.
Preservation of surplus tomatoes by sodium chloride free acidification (top) and fermentation (bottom). (Photo by Fernando Montero)
UM – Americans are usually not too familiar with fermented foods, but they are popular in other parts of the world. How safe are fermented foods?
IP – Fermented vegetables enjoy a strong record of safety; there are almost no outbreaks associated with them. Fermented vegetables are safe for human consumption as long as the microbial growth is controlled, and an appropriate pH level is maintained during storage.
UM – What are the benefits of fermenting or pickling your food?
IP – The main benefit of fermenting or acidifying vegetables is the extension of shelf-life. In certain vegetable fermentations, depending on the microbes, there can be enhanced levels of antioxidant or vitamin content.
However, we must not forget that the main metabolic products in a fermentation are lactic acid and acetic acid, which are building blocks of butyric acid and propionic acid. Such organic acids serve as energy sources for the gut lining, so it’s theoretically possible that fermented foods enhance human gut health. Lactic acid has also been associated with enhanced endurance in athletes who consume fermented vegetables and the juices.
Preservation of cucumbers via acidification in a reduced acid and salt solution. (Photo by Ilenys Perez-Diaz)
UM – Does the degree of fermentation impact the health benefits of a vegetable?
IP – This is a very interesting question. It is unknown to what extent fermented vegetables may enhance human health. However, we do know that butyric acid, the main energy source for the gut tissue lining, can be produced in some vegetable fermentations. Thus, it is of interest to further study the impact of fermented vegetables in the human gut health.
UM – We tend to think of pickled or fermented foods as extremely salty and briny. I understand that you and your team have worked to reduce sodium chloride in processed vegetables – please explain the process and how this can help consumers?
IP – Traditionally, the production of fermented vegetables has depended on the use of 6 to 10% sodium chloride salt in brines to control microbial growth. Salt makes it difficult for most microbes to grow on the vegetable and spoil it. Additionally, salt promotes the growth of bacteria that produce lactic acid, which leads to the desired conversion of sugars to acids.
Although this is a natural process, it can also result in environmental pollution if done on an industrial scale. The brining solution used to turn cucumbers into pickles is high in acidity and salt, which can harm the environment if disposed of improperly. My team and I have managed to replace most of the sodium chloride (table salt) in the brine with calcium chloride. Calcium chloride may improve soil quality and stimulate plant growth.
This new brining solution does not alter the taste or texture of the pickle, but it contains significantly less sodium – something many consumers may appreciate for health reasons.
UM – Recently, people have been interested in consuming probiotic or prebiotic foods like fermented vegetables. Please explain how these types of foods may promote gut health.
IP – Fermented vegetables not only serve as an environment for potentially beneficial microbes to grow, but they also naturally harbor indigestible dietary fibers that feed the gut microbiome. In theory, there is an advantage in using beneficial microbes in fermented foods that are customized to the gut’s natural pH acidity and environment. However, it is difficult to do so due to the level of microbial diversity within each individual’s gut, and also the complexity of microbial interactions within the human body.
Dr. Timothy Artlip, a Plant Physiologist with the USDA-ARS Appalachian Fruit Research Station in Kearneysville, WV, was recently interviewed in the USDA-ARS Under the Microscope publication regarding the future of apple breeding. His work encapsulates efforts to improve the breeding and cultivating of apples through genomics research, and he is bullish about the future. Read the following Q&As from the Under the Microscope (UM):
UM — What are ancient apples and how do they differ from wild apples?
TA — Ancient apples are really just old or antique apple varieties that are no longer grown commercially. Sometimes, these older apples fell out of favor because newer varieties held more appeal to consumers due to appearance, taste, sweet/tart balance or mealiness.
Wild apples, as we define them, are really different species of apples, some of which are actually the ancestor(s) of modern varieties.
UM — Where did the idea of looking into wild apple genes come from?
TA — Plant breeders often look to wild or ancestor species or locally cultivated plants as sources of resistance to diseases or harsh environmental conditions that modern varieties don’t have. In many cases, the genes for such resistance was bred out as a consequence of favoring desirable traits such as flavor, appearance, or some other trait. Potato is a great example. Wild potatoes found in the Andes are usually small and bitter; the bitterness is a sign that insects won’t eat them or of disease resistance. Now potato breeders are trying to reintroduce those types of qualities into modern varieties because of evolving insect and disease pressures.
Modern apples (top row) vs. wild apple species (bottom rows). Wild apples are generally too small for commercial consumption but can still be valuable for apple breeders. (Photo courtesy of Dr. Timothy Artlip)
UM — What are the differences between ancient or wild apples and the commercial apples we find in grocery stores?
TA — Wild apples tend to have small fruits on the order of crab apples, so they’re generally not suitable for consumers. They may not have the appearance or flavor qualities that consumers prefer. A similar situation exists for many old or antique apple varieties that have fallen out of favor. They may be small. They may look “ugly” even under the best growing conditions. They may not keep well in common storage or their flavors and mouthfeel (mealiness) may not be suitable either.
UM — Are there certain types of wild apples that breeders look for and use?
TA — Yes! The main ancestor of modern apples grows throughout central Asia in countries like Kazakhstan in a variety of local conditions, ranging from rather arid to high altitude to having high disease pressure. Other apple species have specific disease resistance or traits that modern apples generally lack
UM — Are ancient or wild apples good for picking and eating, or just breeding?
TA — It depends. Some of the wild apples have fruit that approach commercial size and are edible. Many of the old or antique varieties are very tasty. For example, “Ashmead’s Kernel” was a dessert variety that George Washington would have served to his guests at Mount Vernon. There are also old or antique varieties that were specially bred for cider making that are inedible. With the resurgence in hard cider production, these varieties are especially prized for making a beverage as complex as a quality wine.
UM — What traits do apple researchers and growers specifically breed for?
TA — Besides all the fruit qualities that I’ve mentioned, resistance to diseases, insect pests, and harsh environmental conditions (high/low temperature, too much/too little water) are very important. Growers also look for “friendly” trees that bear fruit within 2 or 3 years after planting, are productive, aren’t biennial (more bloom and fruit on alternate years) or self-thin (too many apples end up being too small, so growers have to chemically or mechanically reduce bloom or very young fruit), growth habit (branching, height) and how well the trees take to modern growing practices.
Forests of wild Malus sierversii in the mountains of Kazakhstan. (Photo courtesy of Dr. Gayle Volk)
UM — How have advancements in technology and genetic sequencing helped apple breeders?
TA — Genetic sequencing has given us a fairly complete accounting of the genome (“instruction manual”) for apples. Moreover, this knowledge along with standard breeding techniques allows us to know what genes are responsible for fruit quality traits such as skin color, sweet/tart balance, and mealiness. Now, breeders can make crosses, isolate DNA from young leaves of offspring, and quickly know whether the seedling will have some/most/all of the desirable traits.
This genomic knowledge has been coupled with “rapid cycle breeding,” where we use a modified variety that blooms within a year after planting and continues to bloom throughout the year in a greenhouse. The cycle can be repeated, reducing the time for creating a consumer and grower desired variety from 15 or 20 years down to 5. This also allows us to respond more quickly to evolving disease, insect, and environmental pressures by breeding better adapted varieties that have the fruit qualities that consumers want.
UM — What challenges are there to using wild apples to cultivate new ones?
TA — As I mentioned with the potato examples, they may have desirable traits, but undesirable traits frequently end up in offspring as well. This requires multiple rounds of breeding to keep what is wanted and discard the rejects.
Years and years of breeding coupled with many acres and the expense of maintaining the trees is not a good economic model. By combining the genetic sequencing and “rapid cycle breeding,” we can introduce those traits we want into commercial varieties much more quickly, with reduced time, land, and inputs.
These wild apples are tough enough to survive erratic conditions like spring snows. This makes them valuable for breeding. (Photo courtesy of Dr. Gayle Volk)
UM — How will breeding traits from wild apples into new apple cultivars benefit growers and consumers?
TA — Consumers have shown a preference for fewer inputs, such as pesticides. Wild apples may have resistance to diseases and pests, thus reducing the need for pesticides. Our group, along with national and international collaborators, recently was able to introduce resistance from wild apples to a disease called Blue Mold that afflicts apples after harvesting. This should reduce fruit losses that can frustrate growers, grocery stores, and consumers. Such efforts are underway with resistance to other diseases as well.
UM — You have mentioned that you and your team have studied how apple trees respond to low temperatures in spring and winter. Is it possible for us to develop an apple variety that will have increased resilience against stresses brought about by climate change?
TA — I firmly believe this. Two climate related problems have emerged. First, protracted warm autumn temperatures followed by sharp temperature drops, may lead to trees unprepared for snow or freezing temperatures. This can lead to broken limbs, freezing damage, or tree death.
Secondly, we frequently see warm spells in late winter or early spring that fool trees into breaking bud or blooming, followed by frosts or visits by the polar vortex. This can result in dead flowers, thus reducing yield or even killing trees. By having the apple genome, scientists across the globe are gaining a better understanding of the interplay of genes involved in stress resistance and dormancy.
UM — What do you predict as the next step in apple breeding?
TA — I think the new genome editing tools, coupled with “rapid cycle breeding,” will gain more acceptance and allow us to more quickly respond to changes or even anticipate them. It really is an exciting time in not only apples but plant breeding in general.
Dr. Timothy Artlip, a Plant Physiologist with the USDA-ARS Appalachian Fruit Research Station in Kearneysville, WV, was recently interviewed in the USDA-ARS 
