By Jennifer Dorsett
Field Editor

Texas A&M AgriLife Extension Service researchers have found a chemical method of inducing male sterility in sorghum plants.

Sorghum, a natural self-pollinator, has long challenged plant breeders seeking to cross plants and create new varieties. Over the past 100 years, scientists have attempted many methods of inducing temporary male sterility in order to cross-pollinate plants.

But the existing methods are either difficult to deploy or ineffective for plant breeding purposes, according to Dr. Bill Rooney, AgriLife Research sorghum breeder.

“We’ve been looking for a way to sterilize sorghum that is not physical or genetic,” Rooney said.

The two most common physical methods of inducing male sterilization in sorghum are hand emasculation, which involves removing the anthers, or male parts, of the plant, and “plastic bag” emasculation where moisture condensation prevents the spread or release of pollen particles before cross-pollination can occur.

Plastic bag and hand emasculation are reliable methods of inducing male sterility in sorghum, but the amount of necessary manual labor involved limits breeding trials to very small groups, according to Rooney.

There are existing chemical methods of inducing male sterility, or gametocides, available, but they are not applicable for sorghum.

So, a few years ago, Rooney asked his research associate, George Hodnett, for help in finding an effective gametocide. Hodnett has been studying the issue ever since.

The researchers finally found success in the chemical trifluoromethanesulfonamide (TFMSA). According to papers recently published by Hodnett, Rooney and their colleagues in the Canadian Journal of Plant Science and Euphytica, TFMSA induces temporary male sterilization in sorghum plants while still allowing full panicle growth.

The offspring are just as fertile and phenotypically identical to hybrids developed with other methods of cross-pollination, Rooney added.

He noted the new breeding tool should help sorghum breeders make more efficient crosses in developing new sorghum hybrids, especially in doubled haploid technology, evaluation of new hybrids and the creation of new breeding populations.

“This should make our breeding programs more efficient and allow us to evaluate more material for improved traits,” Rooney said. “Just like any good tool that provides efficiency, it should translate to faster rates of improvement for the producer.”