Seedless wonders for winter markets.

Any gardener who has planted squash has probably seen the midget and funky-shaped end-of-season fruits that form when some step in the pollination process is out of whack. The misshapen squash make good conversation pieces but are a disaster for the market.

A group of researchers in Europe has genetically engineered a way around the problems that arise when pollination conditions are less than ideal. Application of the technique might improve the look and lot of off-season vegetables. Angelo Spena of the University of Verona in Italy and his colleagues report their findings in the December Nature Biotechnology.

To develop correctly, fruits need a growth hormone produced by their seeds. When fertilization fails and seeds don't form, fruits end up stunted and malformed. For commercial purposes, horticulturists sometimes apply plant growth hormone to the developing flowers to create normal-looking but seedless produce--tomatoes or cucumbers, for example.

Spena's team has instead altered eggplant DNA so that the fruit produces its own growth hormone, with or without seeds. The researchers spliced together a gene from a bacterium, to produce the hormone, and a snapdragon gene that targets the part of the plant where fruit develops.

When they slipped this genetic package Into the eggplant's DNA, the resulting plants bore normal-sized, elongated, purplish fruit. What's more, they bore fruit even under off-season conditions--when low light and low temperatures prevent marketable fruit from developing. "This is the major advantage," says Spena.

The system is also versatile enough to allow for both seedless eggplants and, if the flowers are pollinated, eggplants with seeds. The seeds are viable and carry the engineered trait, the researchers say.

"It's certainly a significant achievement, and it could have potential in a range of different species and under different growth conditions," says Dwight T. Tomes of Pioneer Hi-bred in Johnston, Iowa. He suggests that the technique may work equally well in crops related to eggplant, such as peppers, squash, and tomatoes. Spena's team has also used the technique in the easy-to-manipulate tobacco plant.

Although the researchers have begun to commercialize their technique, "it will probably take further development," says Tomes. Questions concerning such important features as yield and the stability of the transgenic trait in varied environments remain. No word has been published yet on the cost and taste of the engineered eggplant, although aficionado Spena attests that they "are very good roasted" and "excellent" for eggplant, parmigiana.

Even the promise of good taste in genetically engineered produce won't ensure it a lasting place in grocery bins. Three years after it was introduced, the much-heralded Flavr Savr tomato (SN: 5/28/94, p. 432; 11/28/92, p. 342) is off the market because of mass production problems.