Texas Tech University

Dr. Huazhong Shi

Shi

Title: Associate Professor

Education: Ph.D., Wuhan University, China, 1995
Research Associate, University of Arizona, 1999-2001, University of California, 2001-2003, Purdue University, 2003-2004

Research Area: Biochemistry

Office: Chemistry 413-A

Phone: 806-834-7214

Email: huazhong.shi@ttu.edu

Webpage: Research Group



Interested in graduate study on molecular biology and biochemistry? Join the Shi lab! Applicants with strong Biology background are highly encouraged to apply. For more information, click here or contact  Dr. Huazhong Shi.


Principal Research Interests

  • Gene regulation in response to environmental stresses in plants
  • Molecular mechanisms of plant salt tolerance
  • Sulfonation of small molecules and plant stress response
Plants frequently encounter unfavorable conditions that adversely affect their growth, development, and productivity. How plants sense, transduce and respond to abiotic stresses is a fundamental question that is of tremendous significance for the future of agriculture. The research in the Shi lab focuses on understanding how plants cope with environmental stresses at molecular, cellular and organismal levels by employing genetic, molecular and biochemical research tools.

Gene regulation in plant stress response

Fine regulation of gene expression is required for normal growth, development and adaptation to environmental stress conditions in plants. Many genes are repressed at normal growth conditions while activated by stresses. In order to identify regulator proteins mediating gene repression and activation, the Shi lab established a forward genetic screening for mutations affecting gene expression in response to stress conditions. The forward genetic approach utilized a stress-inducible promoter fused with the firefly luciferase reporter gene and a highly sensitive CCD camera to detect bioluminescence generated in small plant seedlings expressing the luciferase gene (Figure 1). By using this high throughput mutant screening system, the Shi lab has identified a number of mutants, designated shiny (shi in short) mutants, showing elevated expression of luciferase gene in response to abiotic stresses. Eight SHI genes have been cloned using map-based cloning. Two of the SHI genes encode proteins forming a complex to regulate stress-inducible gene expression through modulating RNA polymerase II CTD phosphorylation. Another three SHI proteins are mRNA splicing factors that are presumably components of repressor complex modulating stress-inducible gene transcription. Two of the eight SHI genes encode proteins functioning in vesicle trafficking. The Shi lab is employing all available means to study the functions of these SHI genes in order to gain deep understanding of stress-inducible gene repression and activation. In addition, the Shi lab initiated a forward genetic screening for mutations altering heat stress responsive gene expression. Positional cloning of the mutant genes is currently underway.

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Na+ transport and plant salt tolerance

Plants possess three cellular mechanisms to reduce Na+ toxicity, i.e. restricted Na+ entry, Na+ exclusion, and Na+ compartmentation into the vacuole. These three cellular mechanisms are executed by three membrane transporters named AtHKT1, SOS1 and AtNHX1 in Arabidopsis (Figure 2). Through a genetic screening for suppressors of Na+ hypersensitive mutant sos1, the Shi lab identified loss-of-function mutations in AtHKT1 and gain-of-function mutations in AtNHX1 that can suppress the salt sensitivity of sos1 mutant. Single, double and triple mutants with mutations in these three important salt tolerance determinants have been created. The functions of these transporters and their coordination in Na+ uptake, long-distance transport, and redistribution in plants have been studied. Structure-function analysis of the dominant gain-of-function mutations in AtNHX1 and molecular design of superactive AtNHX1 transporters based on such analysis will be our future focus. The ultimate goal of this project is to create salt tolerant crops capable of growing in marginal lands with high salinity to maximize land usage and to secure world food supply.

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Sulfonation of small molecules and its function in plant stress response

Sulfonation of small molecules is an enzymatic process in living organisms catalyzed by sulfotransferases to transfer a sulfonate group from the universal donor 3’-phosphoadenosine 5’-phosphosulfate (PAPS) to the hydroxyl group of various molecules (Figure 3). Sulfonation changes the physiochemical properties and the biological activity of molecules, thus influencing the physiology of organisms. In human, sulfonation of small molecules plays important roles in detoxification of toxic compounds and modulation of steroid hormones. In Arabidopsis, 18 cytosolic sulfotransferases (SOTs) have been identified based on sequence similarity. The Shi lab carried out a genetic and biochemical analysis of the SOT12 and found that SOT12 can sulfonate the plant hormone salicylic acid (Figure 3) and xenobiotic compounds. The role of SOT12 in both biotic and abiotic stress response and tolerance is being studied. The Shi lab is also interested in the functions of other SOTs, in particular, their roles in stress response.

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Representative Publications


"Overexpression of PP2A-C5 that encodes the catalytic subunit 5 of protein phosphatase 2A in Arabidopsis confers better root and shoot development under salt conditions", Hu R, Zhu Y, Wei J, Chen J, Shi H, Shen G, Zhang H. Plant Cell Environ, 2017, 40: 150-164.
"Improved salt tolerance of medicinal plant Codonopsis pilosula by Bacillus amyloliquefaciens GB03", Han Q-Q, Wu Y-N, Gao H-J, Xu R, Pare PW, Shi H, Zhao Q, Li H-R, Khan SA, Wang Y-Q, Suo-Min Wang S-M, Zhang J-L. Acta Physiol Plant, 2017, 39:35.
"Soybean Na+/H+ antiporter GmsSOS1 enhances antioxidant enzyme activity and reduces Na+ accumulation in Arabidopsis and yeast cells under salt stress", Zhao X, Wei P, Liu Z, Yu B, Shi H. Acta Physiol Plant, 2017, 39:19.
"The Nuclear Encoded Chloroplast Protein HCF106 and THF1 Negatively Regulate Drought Resistance in Arabidopsis", Wang Z, Wang F, Hong Y, Huang J, Shi H, Zhu J-K. Plant Physiol, 2016, 172: 2491-2503.
"The Arabidopsis polyamine transporter LHR1/PUT3 modulates heat responsive gene expression by enhancing mRNA stability", Shen Y, Ruan Q, Chai H, Yuan Y, Yang W, Chen J, Xin Z, Shi H. Plant J, 2016, 88: 1006-1021.
“De Novo Assembly and Characterization of Gleditsia sinensis Transcriptome, Genes Identification and SSR Mining”, Han S, Wu Z, Wang X, Huang K, Jin Y, Yang W, Shi H. Genet Mol Res, 2016, 15 (1): gmr.15017740,DOI http://dx.doi.org/10.4238/gmr.15017740.
“Induced growth promotion and higher salt tolerance in the halophyte grass Puccinellia tenuiflora by beneficial rhizobacteria”, Niu S-Q, Li H-R, Pare PW, Aziz M, Wang S-M, Shi H, Li J, Han Q-Q, Guo S-Q, Li J, Guo Q, Ma Q, Zhang J-L. Plant & Soil, 2016, 407:217–230.
“Research advances in higher plant adaptation to salt stress”, Zhang J-L, Li H-R, Guo S-Y, Wang S-M, Shi H, Han Q-Q, Bao A-K, Ma Q. Acta Prataculturae Sinica, 2015, 24: 220-236.
“The role of promoter cis-element, mRNA capping, and ROS in the repression and salt-inducible expression of AtSOT12 in Arabidopsis”. Chen J, Wang B, Chung J-S, Chai H, Liu C, Ruan Y, Shi H. Front Plant Sci, 2015, 6:974. doi:10.3389/fpls.2015.00974.
"RNA-Seq Analysis for Transcriptome Assembly, Gene Identification and SSR Mining in Ginkgo (Ginkgo biloba L.)". Han S, Wu Z, Jin Y, Yang W, Shi H. Tree Genet Genomes, 2015, 11:37, doi: 10.1007/s11295-015-0868-8.
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Department of Chemistry & Biochemistry