In new research reported by scientists at Cold Spring Harbor Laboratory (CSHL), a simple genetic modification can triple the grain number of sorghum, a drought tolerant plant that is an important source of food, animal feed, and biofuel in many parts of the world. Led by CSHL Adjunct Associate Professor and research scientist with USDA's Agricultural Research Service (ARS) Doreen Ware and ARS colleague Zhanguo Xin, the study focused on high-yield strains of sorghum that were generated several years ago by Dr. Xin.
An unknown genetic mutation introduced by chemical mutagenesis resulted in an increase in the number of grains that each plant produced. Sorghum grains are produced in clusters of flowers that develop from a panicle, which produces hundreds of flowers. Only one of the two types of sorghum flowers, known as the sessile spikelet (SS) is fertile. The other flower type, called pedicellate spikelets (PS), do not make seeds. In the modified plants Dr. Xin produced, however, both SS and PS produced seeds, tripling each plant's grain number.
To understand the cause of this change, Ware and her team sequenced the genomes of the modified plants, and they found that the key mutations affected a gene that regulates hormone production. Plants carrying the mutation produce abnormally low levels of the jasmonic acid, particularly during flower development. They learned that jasmonic acid prevents PS from producing seeds. The team now hopes to apply the same strategy to increase grain production in related plants that are vital in the global food supply, such as rice, corn, and wheat.
(Source: Crop Biotech Update, International Service for Acquisition of Agri-Biotech Applications. www.isaaa.org)
