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Research Project: Soybean Seed Improvement Through Translational Genomics, Assessments of Elemental Carbon Metabolism, and Lipid Profiles

Location: Plant Genetics Research

Title: Sterile spikelets contribute to yield in sorghum and related grasses

item AUBUCHON-ELDER, TAYLOR - Danforth Plant Science Center
item CONEVA, VIKTORIYA - Danforth Plant Science Center
item GOAD, DAVID - Danforth Plant Science Center
item JENKINS, LAUREN - Danforth Plant Science Center
item YU, YUNQING - Danforth Plant Science Center
item Allen, Douglas - Doug
item KELLOGG, ELIZABETH - Danforth Plant Science Center

Submitted to: The Plant Cell
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/26/2021
Publication Date: 11/2/2020
Citation: Aubuchon-Elder, T., Coneva, V., Goad, D.M., Jenkins, L.M., Yu, Y., Allen, D.K., Kellogg, E.A. 2020. Sterile spikelets contribute to yield in sorghum and related grasses. The Plant Cell. 32(11):3500-3518.

Interpretive Summary: Plants have evolved to perform very sophisticated functions; however some of the tissues of plants have roles that remain unknown and therefore how they contribute to the yield of a plant or its growth is a mystery. We investigated several small structures called spikelets that are components of sorghum but that have undescribed function. Our results use images from microscopy and biochemical approaches such as data from gene analyses and from studies with isotopic tracers that track the movement of carbon to assess plant function. The investigations indicate that some of the spikelets are capable of photosynthesis and can affect seed weight by 5%.The studies are important because increases in sorghum yield will have implications for food production globally and feeding an ever-increasing world population.

Technical Abstract: Sorghum (Sorghum bicolor) and its relatives in the grass tribe Andropogoneae bear their flowers in pairs of spikelets in which one spikelet (seed-bearing or sessile spikelet [SS]) of the pair produces a seed and the other is sterile or male (staminate). This division of function does not occur in other major cereals such as wheat (Triticum aestivum) or rice (Oryza sativa). Additionally, one bract of the SS spikelet often produces a long extension, the awn, that is in the same position as, but independently derived from, that of wheat and rice. The function of the sterile spikelet is unknown and that of the awn has not been tested in Andropogoneae. We used radioactive and stable isotopes of carbon, RNA sequencing of metabolically important enzymes, and immunolocalization of ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco) to show that the sterile spikelet assimilates carbon, which is translocated to the largely heterotrophic SS. The awn shows no evidence of photosynthesis. These results apply to distantly related species of Andropogoneae. Removal of sterile spikelets in sorghum significantly decreases seed weight (yield) by ~9%. Thus, the sterile spikelet, but not the awn, affects yield in the cultivated species and fitness in the wild species.