Texas A&M research could triple amount of biomass in sorghum

| September 30, 2011

A research team at Texas A&M University has been studying the internal clocks of sorghum hybrids, and they may have found the key to a sorghum hybrid that can accumulate roughly three times the amount of biomass matter. Led by John Mullet, a biochemist at the university’s Agrilife Research center, the team was able to identify a gene that controls flowering in the plant, and the gene is regulated by the plant’s internal clock which allows the plant to flower at the same time each growing season, according to Mullet.

“Flowering time is important for sorghum no matter what type of sorghum is grown,” according to Rebecca Murphy, a member of the research team. “In the case of bioenergy sorghum, you want to delay flowering because the more you delay flowering, the more biomass sorghum will accumulate.”

Murphy helped lead the research effort to genetically map out the sorghum breeds, and doing so helped the team recognize the importance of Maturity Locus 1, a genotype responsible for flowering that was originally found by Texas A&M University researchers in 1945. “In this study, we identified the gene in sorghum that corresponds to Ma4-1. There are mutations in that gene in some sorghum genotypes that inactivate the gene causing plants to flower early,” said Mullet. “But when the gene is active, the plants flower late. It was a variation in the activity of the gene corresponding to Ma1 that sorghum breeders have been using in breeding programs for years to fine-tune when their hybrids flower.”

The work by Mullet, Murphy and the rest of the team, “connected the initial discovery of Ma1 in the 1940’s to the identification of the gene that was regulating when plants would flower,” Mullet said. The team figured out how the internal clock of the plant and day-length combine to express the Ma1 gene, essentially helping them understand when a plant will flower under different conditions. “In a practical sense,” Mullet explained, “we now understand how this gene regulates flowering and this insight is helping us fill in an entire pathway which regulates flowering time in sorghum.”

Certain tweaks to the pathway could delay flowering in hybrid sorghum plants for up to 200 days, Murphy said, compared to the 60-day average for most plants. During a short video describing their work, Murphy highlighted the difference between two sorghum plants, one with a non-expressive Ma1 gene, and one that was altered to allow the Ma1 gene to work. While both plants were 90 days old, one plant stood roughly four feet of the ground, while the other plant was nearly three times the height in comparison to the other plant. The difference Murphy said, “Is quite striking.”