Hsieh, Ming-Hsiun (謝明勳)

Research Fellow

  • Ph.D., Department of Biology, New York University, USA
  • M.S., Department of Botany, National Taiwan University
  • B.S., Department of Botany, National Taiwan University
  • +886-2-2787-1046(Lab)
  • +886-2-2787-1168(Office)
  • ming@gate.sinica.edu.tw
  • Plant molecular nutrition and signal transduction

I. Glutamine/glutamate metabolism and signaling

Glutamine (Gln) and glutamate (Glu), the first organic nitrogen (N) synthesized in the primary N assimilation pathway, serve as the N donors essentially for all organic N compounds in the cell. In addition to their role in metabolism and growth, Gln and Glu may function as signaling molecules to activate plant defense responses (Fig.1). We are interested in the roles of Gln and Glu in regulating plant growth and defense.

Fig. 1 A hypothetical working model for Gln/Glu functions in plant growth and defense. 

Gln/Glu metabolism in Arabidopsis

The Gln synthetase (GS)/Glu synthase (GOGAT) cycle is the primary pathway to assimilate NH4+ in plants (Fig. 1). There are two forms of GS, cytosolic GS1 encoded by a small gene family and chloroplastic GS2 encoded by a single gene in most plants. We are using molecular genetic approaches to study the functions of the chloroplastic GS2/Fd-GOGAT1 cycle in Arabidopsis.

The ACT domain repeat (ACR) proteins are putative amino acid sensors in plants. Arabidopsis has twelve ACRs, and their functions are largely unknown. The ACR11 protein interacts and regulates GS2 and Fd-GOGAT1, but the molecular mechanisms remain elusive. We are interested in studying the functions of Arabidopsis ACRs, including the mechanism of ACR11 in the regulation of the GS2/Fd-GOGAT1 cycle (Fig. 1).

Gln/Glu signaling in Arabidopsis and rice

Gln and Glu can promote plant growth when supplemented as the sole N source. We recently found that extracellular Gln and Glu can activate the expression of defense genes in plants. In addition to their roles as N nutrients, we hypothesize that extracellular Gln and Glu may serve as “danger signals” to activate plant defense (Fig. 1). To study genes involved in Gln/Glu-regulated growth and defense, we screen for Arabidopsis mutants that grow poorly on a medium containing Gln or Glu as the sole N source (Fig. 2). We are in the process of identifying the mutated genes and underlying molecular mechanisms.

Fig. 2 Arabidopsis mutants grown on medium containing Gln or Glu as the sole nitrogen source.

Gln and Glu can function as signaling molecules to rapidly induce the expression of genes involved in metabolism and defense in rice (Oryza sativa). To study the functions of the Gln/Glu-responsive genes, we use the CRISPR/Cas9 technology to generate rice mutants (Fig. 3). Further study on the CRISPR mutants may provide insights into the functions of these genes and the molecular mechanism of Gln/Glu-regulated gene expression in rice.  

Fig. 3 Genotypes and phenotypes of the OsNRG1 CRISPR mutants.

II. Vitamin B1 biosynthesis in plants

Vitamin B1 is an essential cofactor for central metabolic enzymes in all organisms. We have identified the PALE1/THIAMIN-REQUIRING2 (TH2) gene encoding a thiamin monophosphate phosphatase of the vitamin B1 biosynthetic pathway in Arabidopsis and rice (Fig. 4). Rice is a staple food for more than half of the population in the world, but polished white rice is a poor source of vitamin B1. In addition to studying the function of PALE1/TH2, we are interested in genetic engineering for vitamin B1 biofortification in rice. 

Fig. 4 TH2/PALE1 is involved in vitamin B1 biosynthesis in Arabidopsis and rice.

All publication list

Selected publication list

  • Hsieh WY, Wang HM, Chung YH, Lee KT, Liao HS, Hsieh MH* (2022) THIAMIN REQUIRING2 is involved in thiamin diphosphate biosynthesis and homeostasis. Plant J (DOI:10.1111/tpj.15895)
  • Lee KT, Chung YH, Hsieh MH* (2022) The Arabidopsis glutamine synthetase2 mutants (gln2-1 and gln2-2) do not have abnormal phenotypes. Plant Physiol (https://doi.org/10.1093/plphys/kiac224)
  • Liao HS, Yang CC, Hsieh MH* (2022) Nitrogen deficiency- and sucrose-induced anthocyanin biosynthesis is modulated by HISTONE DEACETYLASE15 in Arabidopsis. J Exp Bot 73: 3726-3742
  • Liao HS, Chung YH, Hsieh MH* (2022) Glutamate: A multifunctional amino acid in plants. Plant Sci 318: 111238
  • Hsieh PH, Chung YH, Lee KT, Wang SY, Lu CA, Hsieh MH* (2021) The rice PALE1 homolog is involved in the biosynthesis of vitamin B1. Plant Biotechnol J 19: 218-220
  • Liao HS, Chung YH, Chardin C, Hsieh MH* (2020) The lineage and diversity of putative amino acid sensor ACR proteins in plants. Amino Acids 52: 649-666
  • Hsieh WY, Lin SC, Hsieh MH* (2018) Transformation of nad7 into the nuclear genome rescues the slow growth3 mutant in Arabidopsis. RNA Biol 15:1385-1391
  • Hsieh PH, Kan CC, Wu HY, Yang HC, Hsieh MH* (2018) Early molecular events associated with nitrogen deficiency in rice seedling roots. Sci Rep 8:12207
  • Singh SK, Sung TY, Chung TY, Lin SY, Lin SC, Liao JC, Hsieh WY, Hsieh MH* (2018) ACR11 modulates levels of reactive oxygen species and salicylic acid-associated defense response in Arabidopsis. Sci Rep8: 11851
  • Yang HC, Kan CC, Hung TH, Hsieh PH, Wang SY, Hsieh WY, Hsieh MH* (2017) Identification of early ammonium nitrate-responsive genes in rice roots. Sci Rep 7: 16885
  • Hsieh WY, Liao JC, Wang HT, Hung TH, Tseng CC, Chung TY, MH Hsieh* (2017) The Arabidopsis thiamin deficient mutant pale green1 lacks thiamin monophosphate phosphatase of the vitamin B1 biosynthesis pathway. Plant J 91: 145-157
  • Kan CC, Chung TY, Wu HY, Juo YA, Hsieh MH* (2017) Exogenous glutamate rapidly induces the expression of genes involved in metabolism and defense responses in rice roots. BMC Genomics 18:186

Lab Members

Postdoc: Ting-Chieh Chen, Kamlesh Kumar Soni

Graduate student: Kim Teng Lee

Research assistant: Hong-Sheng Liao, Jia-Ming Chang, Zhi-Yu Guo