Secrets to Sorghum Survival in Acidic Soils
By Ann Perry
November 21, 2008
A gene that protects sorghum from
aluminum in acidic soils has been identified by an
Agricultural Research Service (ARS)
scientist and cooperators.
Acidic soils, which are found around the world, often have aluminum levels
that are toxic to food plants such as sorghum. This finding could help plant
breeders develop sorghum varieties that can be grown by subsistence farmers who
depend on this grain crop for survival.
Kochian leads the
Robert W. Holley Center for Agriculture and Health in Ithaca, N.Y. For this
research, he collaborated with Jurandir V. Magalhaes, a scientist with
Maize and Sorghum, a branch of the Brazilian Agricultural Research
Corporation (EMBRAPA), Brazils federal agricultural research agency.
Aluminum tolerance in wheat is regulated by the aluminum-tolerance gene
ALTM1. When ALTM1 is activated, it triggers the release of malic
acid, which bonds with the aluminum and neutralizes its toxic effect.
The research team found a gene in sorghum that protects the plant from soil
aluminum via mechanisms that closely parallel ALTM1s activity in
wheat. In sorghum, the aluminum tolerance gene prompts the release of citric
acid, which also binds to soil aluminum. But this sorghum
transporterdubbed SbMATEis not related to the ALMT1
The team found that activity of SbMATE is activated in the roots of
aluminum-tolerant sorghum only when aluminum is present in the soil. Under
these conditions, SbMATE is most highly expressed in the first
centimeter of the tip of the root. This optimizes the ability of the
transporter to neutralize the aluminum and protect the sensitive root tip.
ARS and EMBRAPA researchers are now engaged in collaborative projects with
plant breeders in Africa to develop aluminum-tolerant sorghum varieties for
cultivation in African soils.
more about this research in the November/December 2008 issue of
Agricultural Research magazine.
ARS is a scientific research agency in the U.S. Department of Agriculture.