Brazilian Designer Genes May Make Hotter U.S. Petunias

Imagine a greenhouse with perfume-scented petunias--fire-red flowers hot enough to raise a blush, giant 4-foot-high petunias with Pegasus-white blooms. But this greenhouse is no dream: It’s the real-life setting for work by a top U.S. plant breeder, a Brazilian taxonomist and a plant geneticist at USDA’s Agricultural Research Service.

ARS researchers with the U.S. National Arboretum’s Floral and Nursery Plants Research Unit are using the latest techniques in chemical and genetic biology to cross wild Brazilian flowers with American standard varieties. They get the germplasm from breeder Fred Meyer, who traveled with cooperator Joao Stehmann to Brazil’s mountains for cold-tolerant flowers growing in the snow. The giant shrub with big milky blossoms came from Ecuador.

Meyer and Stehmann also found a new drought-tolerant, smooth-leaved petunia species gracing the beaches of the Torres Coast. Its traits offer alternatives to American petunias’ strong scent and low drought tolerance.

ARS researchers working at the floral and nursery research facility know how to solve special breeding problems. They use genetic analysis to differentiate potential petunia “bloodlines” and pick parent plants to create amazing colorful petunias that will someday wow American consumers.

American petunias don’t make great hanging baskets because their hairy leaves and stems turn a decorator’s delight into a household annoyance by clinging to clothes, hair and everything else. But the South American plants aren’t perfect. Brazilian petunias mostly come cloaked with majestic purple blooms. Hybrids need to be created in a variety of colors. The ground-covering coastal petunias spread 4 to 5 feet, but lack the blossoms of U.S. lines. Making Brazilian-U.S. crosses could give consumers the best of both worlds.

Traditional plant breeding fails, as genes for the unwanted traits--like hairiness--reside right next to desirable ones. And first-cross, Brazilian-American offspring can look identical, but only some have the winning genetic combination. This is where ARS techniques break the breeding barrier.

Scientific contact: Robert J. Griesbach, ARS Floral and Nursery Plants Research Unit, U.S. National Arboretum, Beltsville, Md., phone (301) 504-6574, fax (301) 504-5096, rgriesbach@asrr.arsusda.gov.