Scientists Tackle Aluminum Intolerance in WheatBy
Borrowing genes from another plant, such as rye, may be wheat's best hope
for surviving on acidic, high-aluminum soils.
That's the latest word from Agricultural
Research Service scientists and their colleagues abroad who grew U.S. and
Brazilian wheat varieties hydroponically to check the varieties' aluminum
tolerance. They report that none of the modern wheat varieties were any better
equipped to tolerate aluminum-laced soils than BH 1146, developed in Brazil more
than 50 years ago.
Aluminum, found mostly just below topsoil, impairs plant growth on nearly
half of the world's eight billion acres of crop land, including about 86 million
acres in the United States. Lime can be added repeatedly to de-acidify soil,
decreasing plants' vulnerability. But lime is expensive to transport long
While wheat may be lacking in aluminum tolerance genes, those genes are
present in rye, a related species that generally produces less grain.
Geneticist Perry Gustafson and colleagues at ARS'
Research Unit in Columbia, Mo., are finding aluminum tolerance approximately
equal to that of rye in some breeding lines of wheat-rye hybrids, called
triticales, now being developed. Triticales, however, generally are more
suitable for livestock feed than for flour.
Many modern high-yielding bread wheats have genetic resistance to diseases
like powdery mildew, thanks to rye genes that may have been acquired through a
triticale ancestor. Breeding in aluminum tolerance seems a greater--but
The ARS scientists found that numerous wheat genes, lurking somewhere in
various chromosomes, suppress the expression of aluminum tolerance genes from
rye. Genetic sleuthing to locate the most important suppression genes might
take another 10 years. When found, those genes may be replaced with genes that
are more aluminum-friendly through conventional plant breeding or biotechnology.
While the world's population is growing apace, wheat yield increases have
tapered. Until now, most increases have been on fertile soils. In the future,
adequate production may depend increasingly on marginal soils.
Scientific contact: Perry Gustafson,
Research Unit, USDA, Columbia, MO 65211; Phone (573) 882-7318, fax 875-5359,