Genetic discovery points the way to much bigger yields in tomato, other flowering food plants

Every gardener knows the look of a ripe tomato. That bright red color, that warm earthy smell, and the sweet juicy flavor are hard to resist.

But commercial tomato plants have a very different look from the backyard garden variety, which can grow endlessly under the right conditions to become tall and lanky. Tomatoes that will be canned for sauces and juice are harvested from plants that stop growing earlier than classic tomato varieties, and are therefore more like bushes. While the architecture of these compact bushy plants allows mechanical harvesters to reap the crop, the early end of growth means that each plant produces fewer fruits than their home garden cousins.

But what if commercial tomato growers could coax plants into producing more fruit without sacrificing that unique and necessary bushy plant shape? Today, CSHL researchers announced that they have determined a way to accomplish this. Their research has revealed one genetic mechanism for hybrid vigor, a property of plant breeding that has been exploited to boost yield since the early 20th century. Teasing out the hidden subtleties of a type of hybrid vigor involving just one gene has provided the scientists with means to tweak the length of time that bushy tomato varieties can produce flowers. In these plants, longer flowering time substantially raises fruit yield.

First identified at CSHL by George Shull in 1908, hybrid vigor – or heterosis, as biologists call it – involves interbreeding genetically distinct plants to generate offspring more robust than either inbred parent. It has been used for decades to improve agricultural productivity, but scientists have long debated how and why it works.