The good news is, Hutton has made progress toward eliminating linkage drag from one of the major resistance genes—Ty-3—and he now is incorporating this newly developed material into all of his best plant material. He also is working with the university’s office of technology and licensing to get it into the hands of other tomato breeders.
Bacterial leaf spot
Hutton is dealing with two major challenges from bacterial leaf spot.
One is the fact that, after three decades of breeding efforts to combat the disease, new pathogens continue to emerge that overcome resistant genes. Hutton says he believes he has developed an approach that finally may resolve this issue.
The other is dealing with the “nonblighting” trait—which helps a plant to maintain its green leaves even after it’s infected. Hutton says he also believes he is making progress understanding the non-blighting trait, including how many genes control it and where those genes are.
“Knowing their location will then allow more efficient breeding by using molecular markers to identify and select non-blighting plants, even while they are seedlings,” he says. “We’re not quite there, but we’re making progress.”
The university’s tomato-breeding program also has research emphasis in several other areas, including graywall resistance, bacterial wilt resistance and flavor/quality, Hutton says.
Graywall is a cosmetic condition that causes gray blotchiness on the outer skin of a tomato. When the fruit is sliced, there may be brown tissue on the inside of the outer wall. The symptoms typically are not evident until the fruit ripens.
The big problem with finding a cure for graywall is that the cause is not known, Hutton says. However, it seems to show up more often when the weather is cool and in low-light conditions.
Knowing the locations of the resistance genes would help the breeding efforts, he says. Hutton is collaborating on a genetic study, which he hopes will provide a better understanding of graywall resistance.
Bacterial wilt is a problem in some areas of Florida, Hutton says, but it’s actually more of a problem on the East Coast and in other parts of the world.
With bacterial wilt, pathogens get into a plant’s phloem tissue that transports water and basically plugs it so the plants start wilting, especially during the hottest time of the day.