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David Braun

Professor of Biological Sciences
PhD, 1997 University of Missouri

Email: braundm@missouri.edu
Office: 314 Tucker Hall
Phone: 573-882-1055
Headshot of David Braun

Research

Research summary

Genetic control of carbon partitioning in plants

Research description

My lab is interested in the genetic control of carbon partitioning in maize. To characterize genes functioning in this process we have identified mutants that hyperaccumulate starch and soluble sugars in their leaves. Initially, we have focused our attention on mutants that produce variegated leaves as we hypothesize that these may be defective in sensing or signaling the build up of carbohydrates in the tissue. The best characterized is tie-dyed1 (tdy1) which develops leaf regions containing approximately ten-fold higher levels of carbohydrates compared to wild type. Cloning the gene determined that it encodes a novel protein expressed in the phloem. From our phenotypic and molecular expression studies, we propose that TDY1 acts as a sugar flux or an osmotic stress sensor to up-regulate sugar export into the veins, possibly through controlling sucrose transporters. Intriguingly, in response to the elevated sugar levels, the ultrastructure of the cell wall is altered, which we determined is associated with increased cellulose deposition. Ongoing research focuses on determining the function of TDY1, determining the biological functions of all maize and sorghum sucrose transporters, characterizing additional carbon hyperaccumulation mutants, and investigating the utility of manipulating the flux of carbon to the cell wall for biofuels production.

Select Publications

Select Publications

Bihmidine S, Julius BT, Dweikat I, Braun DM: Tonoplast sugar transporters (SbTSTs) putatively control sucrose accumulation in sweet sorghum stems. Plant Signaling and Behavior 2016, 11(1).

Baker, R.F., Leach, K.A., Boyer, N.R., Swyers, M.J., Benitez-Alfonso, Y., Skopelitis, T., Luo, A., Sylvester, A., Jackson, D., Braun, D.M. Sucrose transporter ZmSut1 expression and localization uncover new insights into sucrose phloem loading (2016) Plant Physiology, 172 (3), pp. 1876-1898.

Eom JS, Chen LQ, Sosso D, Julius BT, Lin IW, Qu XQ, Braun DM, Frommer WB: SWEETs, transporters for intracellular and intercellular sugar translocation. Current Opinion in Plant Biology 2015, 25:53-62.

Rotsch D, Brossard T, Bihmidine S, Ying W, Gaddam V, Harmata M, Robertson JD, Swyers M, Jurisson SS, Braun DM: Radiosynthesis of 6'-deoxy-6'[18F] fluorosucrose via automated synthesis and its utility to study in vivo sucrose transport in Maize (Zea mays) leaves. PLoS ONE 2015, 10(5).

Bihmidine, S, Baker, RF, Hoffner,C , Braun, DM Sucrose accumulation in sweet sorghum stems occurs by apoplasmic phloem unloading and does not involve differential Sucrose transporter expression. 2015 BMC Plant Biology, 15(1), 186

Settles AM, Bagadion AM, Bai F, Zhang J, Barron B, Leach K, Mudunkothge JS, Hoffner C, Bihmidine S, Finefield E et al: Efficient molecular marker design using the maizeGDB Mo17 SNPs and indels track. G3: Genes, Genomes, Genetics 2014, 4(6):1143-1145.

Braun DM, Wang L, Ruan YL: Understanding and manipulating sucrose phloem loading, unloading, metabolism, and signalling to enhance crop yield and food security. Journal of Experimental Botany 2014, 65(7):1713-1735.

Bihmidine S, Hunter Iii CT, Johns CE, Koch KE, Braun DM: Regulation of assimilate import into sink organs: Update on molecular drivers of sink strength. Frontiers in Plant Science 2013, 4(JUN).

Baker RF, Slewinski TL, Braun DM: The Tie-dyed pathway promotes symplastic trafficking in the phloem. Plant Signaling and Behavior 2013, 8(6):e24540-24541-e24540-24546.

Braun DM: Sweet! The pathway is complete. Science 2012, 335(6065):173-174.

Slewinski TL, Frank Baker R, Stubert A, Braun DM: Tie-dyed2 encodes a callose synthase that functions in vein development and affects symplastic trafficking within the phloem of maize leaves. Plant Physiology 2012, 160(3):1540-1550.

Baker RF, Leach KA, Braun DM: SWEET as sugar: New sucrose effluxers in plants. Molecular Plant 2012, 5(4):766-768.

Slewinski TL, Braun DM. The Psychedelic genes of maize redundantly promote carbohydrate export from leaves, Genetics, 2010, 185: 221-232

Slewinski TL, Braun DM. Current perspectives on the regulation of whole-plant carbohydrate partitioning, Plant Science, 2010, 178: 341-349

Huang M, Braun DM. Genetic analyses of cell death in maize (Zea mays, Poaceae) leaves reveal a distinct pathway operating in the camouflage1 mutant. American Journal of Botany, 2010, 97: 357-364

Slewinski TL, Garg A, Johal GS, Braun DM. Article Addendum: Maize SUT1 functions in phloem loading, Plant Signaling & Behavior, 2010, 5:1-4.