Nuts about peanuts: How can science help the peanut industry?

Americans consume about 700 million pounds of peanut butter each year, but how much do you actually know about the star of the nutty spread? 

For starters, peanuts are not actually nuts. Because the edible seeds are enclosed in a pod, or shell, peanuts are classified as legumes, a member of the bean family. However, unlike some of their bean relatives that grow on vines, peanuts grow their pods underground.

The Life of a Peanut

Peanuts are grown as a row crop, meaning farmers plant peanut seeds in long rows about three feet apart. Roughly two weeks after being planted in soil, peanut seeds grow into a plant that can reach 18-inches tall. Interestingly, although peanut fruits, or pods, grow underground, their flowers grow above-ground near the lower portion of the plant. 

Peanut flowers contain both male and female parts, allowing them to self-pollinate. Once fertilized, the flowers lose their petals and begin to grow down away from the plant, eventually extending into the soil to grow into a mature peanut pod. The plant will continue to grow and flower, producing 40 or more pods below the surface of a single peanut plant. 

Because they grow underground, harvesting peanuts requires a two-step process. First, a digger machine pulls the plants up from the ground and flips them over so the peanuts are exposed. Then, after several days of drying above-ground, the farmer drives a combine over the rows to separate the pods from the plants. 

The average peanut farm is about 200 acres, or roughly 152 football fields. Harvesting such a large crop of peanuts requires several weeks. Experienced growers can determine which fields need to be harvested first to ensure a high-yield of mature peanuts. From planting to harvesting, the growing cycle takes about four to five months depending on the type or variety of peanut. 

Peanut varieties 

Speaking of different types of peanuts, did you know that the peanuts in peanut butter and those you eat straight out of the shell at the ballpark are not the same? In fact, there are four market types of peanut grown in the United States. Each of the peanut types is distinct in size, flavor, and nutritional composition. 

Runner peanuts are the most common type, accounting for about 85% of the peanut production in the US. This variety is grown mainly in Alabama, Georgia, Florida, Texas, and Oklahoma. They are used predominantly to make peanut butter and candies containing peanuts. 

The Virginia type of peanuts are considered the “gourmet” peanut. Contrary to what their name suggests, they are not solely grown in Virginia but are also grown in parts of North Carolina, South Carolina, and Texas. They have large kernels (the edible part of the peanut) and account for most of the peanuts that are roasted and processed in-the-shell. If you’ve eaten a bag of in-shell peanuts then you’ve likely eaten a Virginia peanut. 

The two less common varieties in the US are Spanish and Valencia peanuts, which collectively account for less than five percent of the peanut market in the US. Both types are mainly grown in the Midwest. Spanish type peanuts have smaller kernels covered in a reddish-brown skin. They are predominantly used in peanut candy, but can also be used for salted nuts and peanut butter. Valencia peanuts usually have three or more kernels per pod. They are normally roasted and sold in the shell. 

What makes a successful peanut harvest? 

In order to keep up with America’s growing peanut eating habits—clocking in at 7.6 pounds of peanuts per person this year—peanut growers must produce a maximum number of peanuts per acre of land. This usually means staying one step ahead of Mother Nature and the many threats peanuts face throughout the growing season. So, what factors actually influence a peanut harvest? 

Common threats to a successful peanut season include destructive pests that can decimate an entire field of peanuts, funguses that are attracted to the humid environments in which peanuts thrive, toxins such as aflatoxin that are produced by fungi, and weather events such as drought, heavy periods of rain or late freezes. In order to combat these potential threats, farmers rely on fungicides, pesticides, fertilizers, and irrigation systems. However, these treatments and regimens are costly and time consuming. 

How can science help the peanut industry? 

What if there was a way to create a peanut that was disease-resistant, drought-resistant and produced an outstanding yield each season without the need for fertilizers or excess water? It turns out, with the help of agricultural science, creating peanut plants with desirable traits is a possibility.   

Agricultural researchers, like those at the HudsonAlpha Institute for Biotechnology, use crop breeding and genetics to produce healthier, more productive plants. To do this, researchers plant peanuts and sequence their genomes when they are still small. By comparing the young plant’s genomes to a peanut reference genome, the researchers are able to determine which plants have the desired genetic traits, like disease or drought resistance. HudsonAlpha researchers, in collaboration with the University of Georgia and USDA Stoneville, actually sequenced the first tetraploid peanut genome, giving researchers a point of reference when looking for the desired genetic trait. The plants with the desired traits are then used to create the next generation of peanuts, hopefully leading to a peanut line that can be deployed for farmers to use.  

The peanut genome sequencing does not stop there though. Recently, HudsonAlpha, along with collaborators at Auburn University’s College of Agriculture, received a $490,000 USDA-National Institute of Food and Agriculture (NIFA) funded grant to accelerate efforts to breed a drought-tolerant peanut plant. During the three-year grant, HudsonAlpha researchers, led by Faculty Investigator Jeremy Schmutz, will sequence genomes and examine expression in peanut lines grown in drought conditions to determine the DNA variants that distinguish the most drought-tolerant and susceptible peanut cultivars. Drought-tolerant peanut plants would decrease the amount of water needed during a crop year, leading to a higher-yield harvest and a reduction in the use of a precious natural resource, water.

HudsonAlpha Faculty Investigator Josh Clevenger, PhD, knows a thing or two about breeding valuable peanut lines. As HudsonAlpha’s resident peanut expert, he brings nearly eight years of experience working in the field of peanut breeding and genetics to the HudsonAlpha Center for Plant Science and Sustainable Agriculture. Clevenger is the Principal Investigator on projects funded by the Peanut Research Foundation, the National Peanut Board, and the United States Agency for International Development (USAID) Peanut Innovation Lab. The projects involve identifying natural variation for drought tolerance, low aflatoxin contamination, and disease resistance. He also serves as co-principal investigator on projects funded by USDA-NIFA and Mars Wrigley to identify and incorporate resistance to fungal diseases and viruses and low aflatoxin contamination into cultivated peanuts.