From Hawaii to You

Flavorful Coffees You’re relaxing at a neighborhood Islands, earning them their and café, savoring a cup of your favorite nickname “America’s Coffee roast and a decadent slice of choco- Islands.” Creamy late macadamia nut torte. The tropi- cal beans used to brew your coffee Uncovering the Beans’ Macadamia and the rich, buttery nuts embedded Genes in the torte may have come to you To discover more about cof- from the farms of the sunny Hawai- fee and macadamia nut genetic Nuts ian Islands. material, the researchers are ex-

Scientists with the ARS U.S. amining the makeup of specific PEGGY GREB (K11220-1) Pacific Basin Agricultural Research Center in Hawaii, and their stretches of DNA. Snipping In preparing to identify colleagues, are discovering more about the genetic makeup of corresponding stretches from potential causal agents of these exotic tropical crops. Their research should benefit not each of the individual species grey kernel disease of only growers, but also coffee lovers and macadamia nut fans. ensures a stable, valid basis of macadamia, plant pathologist One of the scientists’ goals is to ensure that the genetic di- comparison. Any dissimilarities Lisa Keith examines macadamia nuts for hairline versity, or gene pool, of both crops is preserved for the future. among the DNA samples could cracks, which seem to be For example, as-yet-unknown genes in today’s popular com- be important, helping reveal the necessary for symptoms to mercial coffee varieties or in their wild, uncultivated relatives location of interesting genes— develop. might hold the key to innovative new coffees for tomorrow. In such as one that makes a parti- the case of macadamia, the investigations could streamline cular species more hardy or breeding of superior trees that boast genes for bigger yields of flavorful than others. this premium nut. Coffee plant leaves used for the tests came from a genebank A Little History assembled by University of Hawaii scientists and maintained Macadamia nut and coffee plants by the grower-sponsored Hawaii Agri- sailed into Hawaii—literally—in the PEGGY GREB (K11227-1) culture Research Center, based at Aiea. 1800s. Hawaii was an important stop- The researchers analyzed three coffee ping point for sailors to restock provi- species from Africa, the likely origin of sions needed for their long voyages. coffee. Coffea arabica, the source of Though macadamia devotees may find today’s premium beans, and C. cane- it hard to believe, macadamia trees were phora, known for the robusta beans first imported into Hawaii for landscap- commonly used for making instant ing and establishing pleasant woodlands, coffees, are the two most widely grown and only later were cultivated for their coffees in the world. C. liberica is grown tasty, unusual nuts. commercially in the Philippines as well Coffee was first transported to the as in parts of Africa. Hawaiian Islands via a British gunship When researchers compared these that was carrying home the bodies of species, they found significant variation: King Kamehameha II and Queen C. arabica, for example, was about 50 Kamamalu, who had died of measles percent different from C. canephora and during a state visit to London. The ship C. liberica. Says ARS plant physiologist took coffee trees aboard during a stop- Paul H. Moore, “The beans from these over for supplies in Rio de Janeiro. The species make very different brews. The rest is history. species grow at different elevations and Both coffee and macadamia flourished differ in their resistance to pests. Perhaps in Hawaii’s mild climate. Today, maca- some of those differences are reflected damia nuts—known as “mac nuts” to in the variations in the genetic material island locals—are grown mainly on the Plant physiologist Paul Moore examines that we examined.” Big Island of Hawaii, while coffee is coffee trees involved in genetic studies on the Nearly all the C. arabica varieties Island of Oahu. produced throughout the Hawaiian examined—Bourbon, Catimor, Catuai, Caturra, and Mokka Hybrid—were, on

18 Agricultural Research/June 2004 Macadamia nuts, from Macadamia integrifolia. Photo by Peggy Greb. (K11222-1)

Agricultural Research/June 2004 19 average, 93 percent similar among the stretches of DNA unique new nuts for Hawaii’s orchards—a boon for mac nut analyzed. Catimor and Mokka Hybrid differed the most from lovers around the world. each other—information that could eventually result in a better These studies are the most comprehensive genetic analyses cup of joe. to date of cultivated arabica coffees and cultivated macadamia nut varieties—and the first to use a sophisticated laboratory Probe Zeros In on Mac Species technique called AFLP (amplified fragment length polymor- America’s official macadamia nut genebank at Hilo, phism). Delving even further into the variations among and Hawaii—about 45 minutes by plane from Honolulu—provided within macadamia nut and coffee species may lead scientists leaf samples for the macadamia nut study. ARS horticulturist to genes that control desirable traits, enabling future advances Francis T.P. Zee manages the collection, which includes that may make your coffee and torte that much more delecta- macadamia nut types grown in Hawaii, California, Australia, ble.—By Marcia Wood, ARS. South Africa, and Thailand. This research is part of Plant, Microbial, and Insect Genetic The macadamia nut study is helping to clarify key genetic Resources, Genomics, and Genetic Improvement, an ARS differences among four of the world’s seven macadamia species, National Program (#301) described on the World Wide Web at as well as a wild relative with the evocative name rose nut or www.nps.ars.usda.gov. Hicksbeachia pinnatifolia. Of the five species examined, only Paul H. Moore is with the USDA-ARS U.S. Pacific Basin Macadamia integrifolia and M. tetraphylla bear edible nuts; Agricultural Research Center, Tropical Plant Physiology, M. ternifolia, M. hildebrandii, and rose nut do not. Disease, and Production Unit, 99-193 Aiea Heights Drive, Aiea, Scientists found that the two macadamia species that produce HI 96701; phone (808) 486-5411, fax (808) 486-5020, e-mail edible nuts were the most similar to each other. According to [email protected]. plant molecular geneticist Ray Ming of the Hawaii Agriculture Francis T. P. Zee is with the USDA-ARS U.S. Pacific Basin Research Center, who led Agricultural Research Cen- PEGGY GREB (K11224-1) the investigation, macada- ter, Pacific Basin Tropical mia nut species were, on Plant Genetic Resource average, about 26 percent Management Unit, P.O. Box different. This is a rela- 4487, Hilo, HI 96720; tively high level of genetic phone (808) 959-5833, fax diversity and means there’s (808) 959-3539, e-mail fzee enough variation to breed @pbarc.ars.usda.gov. ★

One of 43 macadamia accessions maintained as field plantings at the U.S. Pacific Basin Agricultural Research Center.

20 Agricultural Research/June 2004