LINDELL BEACH, B.C. — Root-knot nematodes are destructive root parasites that infect thousands of plant species, including horticultural and field crops.
About 2,000 plant species and subspecies are at risk of infection, and the nematodes cause about five percent of global crop loss.
The worm larvae infect plant roots and cause galls that drain nutrients, which kills young plants and reduces yields in mature plants. They can overwinter and infect the following season’s crop.
Now researchers at the University of California, Davis, think they have found a resistant strain of wheat called Lassik that can reduce nematode numbers in the soil and also protect the following crop.
Read Also
Interest in biological crop inputs continues to grow
It was only a few years ago that interest in alternative methods such as biologicals to boost a crop’s nutrient…
Valerie Williamson of the university’s nematology department expects future research will test the wheat in larger field trials.
The team hopes to raise awareness about the value of the wheat strain to see if it is as successful in normal farming practices as it has been shown to be in test plots. Williamson’s tests involved tomatoes in a rotation with the wheat.
“The region of the chromosome that carries the root-knot nematode resistance came from a wild relative of wheat and also carries some resistance against other diseases such as stripe rust, leaf rust, stem rust and cereal cyst nematodes,” said Williamson, lead author of a study published in Crop Science.
Williamson said using wheat as a rotational crop to tomatoes is important because both crops in the rotation have value.
Plants susceptible to the root-knot nematode include squashes, melons, pumpkins, cucumbers, gourds and others in the cucurbitaceous family.
The resistant wheat strain, Lassik, is a hard red spring derived from Anza. It is similar to other commonly grown wheat strains but has a slight genetic difference.
It has three stripe rust resistant genes and two genes for resistance to leaf rust.
It also has good levels of resistance to septoria tritici blotch and barley yellow dwarf virus.
A small segment of genes from another wheat strain had been relocated into Lassik.
The genetic segment had no negative effect on growth or yield but provided a booster for resistance to other pathogens. Finding that it was also nematode resistant was a bonus.
To confirm their findings, the research team compared pairs of wheat strains with and without the relocated genetic segment.
They then took the soil in which Lassik had been grown and used it as a soil base in which to plant tomato seedlings.
Tomatoes grown in the soil in which Lassik had previously grown proved to be less damaged by root-knot nematodes.
For a farmer who uses wheat as a rotation crop, choosing a commercial strain with nematode resistance would be insurance that the soil would not harbour as many nematodes ready to infest next season’s crop.
Lassik has a prominent high grain protein and stronger gluten than Anza, giving it superior bread making characteristics. In 2011, Lassik was the top yielding variety in a Washington State University hard spring wheat trial.
Researchers do not have enough data to know if the benefit extends into several years or simply one year, and they do not yet know exactly what the resistance gene contains.
“We only know it is there because the wheat is resistant. That is, the nematodes enter the root but few develop and produce progeny. This is in contrast to many commonly used varieties of wheat,” said Williamson.
