Nav: Home

Breeding beans that resist weevils

October 24, 2018

Beans are awesome. They are packed with nutrients and are high in protein. They can grow in many different environments. They help replenish soil nitrogen levels. They are a vital crop for food security in many parts of the world.

But a small beetle can cause big losses to bean crops.

The common bean weevil can infest beans in the field or in storage. Weevil larvae bore into seed pods and enter seeds. They continue feeding inside the seeds until coming out as adults to infect more seeds.

Weevil infestations can spread rapidly and lead to significant losses of bean crops. In fact, under favorable conditions, weevils can infest entire quantities of stored beans within a few months. Researchers hope to change that.

"Developing varieties of beans that are resistant to the bean weevil is a long-term solution to a very serious problem," says Kelvin Kamfwa, bean breeder at the University of Zambia.

Kamfwa is the lead author of a new study that has narrowed down the genetic locations of several weevil resistance genes in the common bean. The study confirmed that weevil resistance in beans is genetic. Resistance to weevils can be transferred to bean plants with different seed types and colors.

"This will allow breeders in different countries to introduce weevil resistance into bean varieties adapted to local conditions," says Kamfwa.

The study also showed that weevil resistance is inherited separately from seed size in beans. That's important because earlier studies suggested a relationship between weevil resistance and seed size. If true, that would prevent plant breeders from developing larger-seeded beans with weevil resistance.

"Beans with larger seeds are preferred by consumers in several areas of Africa," says Kamfwa. This means growers will have eager buyers, ensuring the growers' livelihood.

Bean varieties that are resistant to weevils can help farmers in the field and when it's time to store harvests.

In some areas, farmers currently treat bean seeds with ash from cooking fires to control weevils. "But that's not particularly effective," says Kamfwa. Treating seeds with chemicals can be effective but is costly and may carry health risks. Suffocating weevils by triple bagging beans in storage is another option, but effective bags may not always be available.

Weevil-resistant bean varieties will allow farmers the flexibility to store seeds. "They will be able to save seeds for home use or for the next planting season," says Kamfwa. "They may even store seeds to sell when prices are more favorable."

To learn more about the genetics of weevil resistance in the common bean, Kamfwa and his colleagues used bean plants derived from an initial mating between a weevil-resistant and a weevil-susceptible variety of common bean.

For each bean plant tested, the researchers calculated the percentage of bean seeds damaged by weevils. This measurement provided a quantitative idea of how resistant each bean plant was to weevils.

The researchers also sequenced the entire DNA of the bean plants. Then they combined the weevil-resistance measurements with the DNA sequence information.

Finally, the researchers used statistical analyses to find genetic signals-called markers-that are more common in the DNA of bean plants resistant to weevils. These genetic signals act like molecular beacons, allowing the researchers to hone in on regions of bean DNA that are important for weevil resistance.

"Using bean plants directly to research weevil resistance can be complicated and time-consuming," says Kamfwa. "Being able to indirectly look for resistance with genetic markers will bring efficiency to the breeding process."

The researchers found three regions of bean DNA important for weevil resistance. One of these regions was known previously, but two regions were new discoveries.

Kamfwa intends to develop a genetic marker system that can be widely used by bean breeders interested in developing weevil-resistant varieties.

"Ultimately, we hope our findings contribute to food security needs in countries where the common bean is a valuable staple food," he says.
-end-
Read more about this research in Crop Science. This research was funded by USAID through the Legume Innovation Lab at Michigan State University.

American Society of Agronomy

Related Dna Articles:

Scientists now know what DNA's chaperone looks like
Researchers have discovered the structure of the FACT protein -- a mysterious protein central to the functioning of DNA.
In one direction or the other: That is how DNA is unwound
DNA is like a book, it needs to be opened to be read.
DNA is like everything else: it's not what you have, but how you use it
A new paradigm for reading out genetic information in DNA is described by Dr.
A new spin on DNA
For decades, researchers have chased ways to study biological machines.
From face to DNA: New method aims to improve match between DNA sample and face database
Predicting what someone's face looks like based on a DNA sample remains a hard nut to crack for science.
Self-healing DNA nanostructures
DNA assembled into nanostructures such as tubes and origami-inspired shapes could someday find applications ranging from DNA computers to nanomedicine.
DNA design that anyone can do
Researchers at MIT and Arizona State University have designed a computer program that allows users to translate any free-form drawing into a two-dimensional, nanoscale structure made of DNA.
DNA find
A Queensland University of Technology-led collaboration with University of Adelaide reveals that Australia's pint-sized banded hare-wallaby is the closest living relative of the giant short-faced kangaroos which roamed the continent for millions of years, but died out about 40,000 years ago.
DNA structure impacts rate and accuracy of DNA synthesis
DNA sequences with the potential to form unusual conformations, which are frequently associated with cancer and neurological diseases, can in fact slow down or speed up the DNA synthesis process and cause more or fewer sequencing errors.
Changes in mitochondrial DNA control how nuclear DNA mutations are expressed in cardiomyopathy
Differences in the DNA within the mitochondria, the energy-producing structures within cells, can determine the severity and progression of heart disease caused by a nuclear DNA mutation.
More Dna News and Dna Current Events

Top Science Podcasts

We have hand picked the top science podcasts of 2019.
Now Playing: TED Radio Hour

In & Out Of Love
We think of love as a mysterious, unknowable force. Something that happens to us. But what if we could control it? This hour, TED speakers on whether we can decide to fall in — and out of — love. Guests include writer Mandy Len Catron, biological anthropologist Helen Fisher, musician Dessa, One Love CEO Katie Hood, and psychologist Guy Winch.
Now Playing: Science for the People

#543 Give a Nerd a Gift
Yup, you guessed it... it's Science for the People's annual holiday episode that helps you figure out what sciency books and gifts to get that special nerd on your list. Or maybe you're looking to build up your reading list for the holiday break and a geeky Christmas sweater to wear to an upcoming party. Returning are pop-science power-readers John Dupuis and Joanne Manaster to dish on the best science books they read this past year. And Rachelle Saunders and Bethany Brookshire squee in delight over some truly delightful science-themed non-book objects for those whose bookshelves are already full. Since...
Now Playing: Radiolab

An Announcement from Radiolab