Crop rotation with nematode-resistant wheat can protect tomatoes

From phys.org:

In a study published online today in Crop Science, scientists describe a nematode-resistant wheat. But while the wheat carries the resistance to the pest, the benefits are actually seen in the crop that is grown after it.

Root-knot nematodes cause crop losses around the world, and they can be difficult to control. In order to reproduce, nematodes need to infect a living plant root. Once they are present in soil, they can survive winter in a fallow field and infect plants during the next growing season. Trap crops – unsuitable hosts that "trick" the nematodes into starting their life cycle but then prevent them from reproducing – are often a better option than leaving the field fallow.

"Once nematodes commit to being a parasite, they have to complete their life cycle," explains Valerie Williamson, lead author of the study and professor at University of California – Davis. "If they don't reproduce, the population dies out."

Trap crops can reduce the number of parasites in the soil and lessen the effects of the pests on the next crop in the rotation. But crops resistant to nematodes can be hard to find due to the pest's wide range of hosts, and trap crops are often plants that are less valuable to farmers. In the present study, researchers found a resistant strain of wheat that can reduce nematode numbers in soil and protect the next rotation of tomato plants.

"What's nice about this finding is that wheat is what farmers often use as a rotation crop in California," says Williamson.

The researchers were surprised to find the resistant wheat. They had tried a number of different rotation crops before turning to wheat. Wheat breeder and senior co-author Jorge Dubcovsky then gave Williamson a strain of wheat called Lassik. Lassik is similar to wheat that is commonly grown, but it has a slight difference. A small segment of genes from another wheat strain relocated, through breeding, into Lassik.

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