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John Mullet

Mullet, John
John Mullet
Perry L. Adkisson Chair in Agricultural Biology; Professor of Biochemistry and Biophysics
BioBio / 306A
Undergraduate Education
B.S. Colgate University (1976)
Graduate Education
Ph.D. University of Illinois, Champaign (1980)
Postdoc. Rockefeller University (1980-83)
Joined Texas A&M in 1983

Functional Genomics of Plants

Plant productivity needs to double to provide food, feed, biofuels and bio-products for a world population that will reach 9-10 billion by 2050. Current rates of crop improvement are insufficient to meet expected demand creating a yield gap. Knowledge of complete genome sequences, advanced genomic and gene editing technologies, modeling, and high throughput phenotyping capabilities provide an unprecedented opportunity to understand fundamental plant function and to engineer improvements in crop yield, resilience, and composition needed to fill the yield gap.

Our research is focused on the C4 grass sorghum, one of the most productive and environmentally resilient plants used to produce grain, forage, biofuels and other bio-products, especially in drought prone regions of the world. Sorghum was selected for drought and heat tolerance and numerous other useful traits in Africa over the past 50 million years. Sorghum is an excellent genetic system, with a diverse germplasm, >100 complete genome sequences and efficient processes for gene discovery and genomics-aided design. The Mullet laboratory is using a combination of genetic, genomic and biochemical approaches to accelerate analysis of sorghum’s unique traits and to engineer pathways that can add value to this hybrid crop.

We are currently investigating the molecular mechanisms that regulate several key traits/pathways: (1) flowering time, a process coordinately regulated by the circadian clock and input from temperature and photo-sensing pathways, (2) drought resilience and water use efficiency, due in part to optimal root and leaf architecture, and regulated water uptake and utilization, and (3) biochemical pathways that modulate stem growth and composition. In collaboration with numerous groups, we have helping to develop high biomass sorghum genotypes that are 4-5 meters tall with large stems that accumulate sugars and other useful biopolymers. Engineering stems with improved cell wall composition that accumulate valuable biopolymers will generate new sources of feed, biofuels, and biomaterials to help fill the world’s yield gap.

Recent Publications

  1. Kebrom, TH, McKinley, BA, Mullet, JE. Shade signals alter the expression of circadian clock genes in newly-formed bioenergy sorghum internodes. Plant Direct. 2020;4 (6):e00235.
    doi: 10.1002/pld3.235. PubMed PMID:32607464. PubMed Central PMC7315773.

  2. McKinley, BA, Casto, AL, Rooney, WL, Mullet, JE. Developmental dynamics of stem starch accumulation in Sorghum bicolor. Plant Direct. 2018;2 (8):e00074.
    doi: 10.1002/pld3.74. PubMed PMID:31245742. PubMed Central PMC6508807.

  3. Casto, AL, McKinley, BA, Yu, KMJ, Rooney, WL, Mullet, JE. Sorghum stem aerenchyma formation is regulated by SbNAC_D during internode development. Plant Direct. 2018;2 (11):e00085.
    doi: 10.1002/pld3.85. PubMed PMID:31245693. PubMed Central PMC6508845.

  4. Casto, AL, Mattison, AJ, Olson, SN, Thakran, M, Rooney, WL, Mullet, JE et al.. Maturity2, a novel regulator of flowering time in Sorghum bicolor, increases expression of SbPRR37 and SbCO in long days delaying flowering. PLoS ONE. 2019;14 (4):e0212154.
    doi: 10.1371/journal.pone.0212154. PubMed PMID:30969968. PubMed Central PMC6457528.

  5. McKinley, BA, Olson, SN, Ritter, KB, Herb, DW, Karlen, SD, Lu, F et al.. Variation in energy sorghum hybrid TX08001 biomass composition and lignin chemistry during development under irrigated and non-irrigated field conditions. PLoS ONE. 2018;13 (4):e0195863.
    doi: 10.1371/journal.pone.0195863. PubMed PMID:29684037. PubMed Central PMC5912772.

  6. McCormick, RF, Truong, SK, Sreedasyam, A, Jenkins, J, Shu, S, Sims, D et al.. The Sorghum bicolor reference genome: improved assembly, gene annotations, a transcriptome atlas, and signatures of genome organization. Plant J. 2018;93 (2):338-354.
    doi: 10.1111/tpj.13781. PubMed PMID:29161754. .

  7. Hilley, JL, Weers, BD, Truong, SK, McCormick, RF, Mattison, AJ, McKinley, BA et al.. Sorghum Dw2 Encodes a Protein Kinase Regulator of Stem Internode Length. Sci Rep. 2017;7 (1):4616.
    doi: 10.1038/s41598-017-04609-5. PubMed PMID:28676627. PubMed Central PMC5496852.

  8. Kebrom, TH, McKinley, B, Mullet, JE. Dynamics of gene expression during development and expansion of vegetative stem internodes of bioenergy sorghum. Biotechnol Biofuels. 2017;10 :159.
    doi: 10.1186/s13068-017-0848-3. PubMed PMID:28649278. PubMed Central PMC5480195.

  9. Mullet, JE. High-biomass C4 grasses-Filling the yield gap. Plant Sci. 2017;261 :10-17.
    doi: 10.1016/j.plantsci.2017.05.003. PubMed PMID:28554689. .

  10. Truong, SK, McCormick, RF, Mullet, JE. Bioenergy Sorghum Crop Model Predicts VPD-Limited Transpiration Traits Enhance Biomass Yield in Water-Limited Environments. Front Plant Sci. 2017;8 :335.
    doi: 10.3389/fpls.2017.00335. PubMed PMID:28377779. PubMed Central PMC5359309.

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