A novel rice protein family of OsHIGDs may be involved in early signalling of hypoxia-promoted stem growth in deepwater rice.
OsHIGDs was identified as a novel hypoxia-responsive protein family. Among them, OsHIGD2 is characterized as a mitochondrial protein and is related to hypoxia signalling through interacting with mitochondrial proteins of critical functions in reducing cell damages caused by hypoxia. Recent evidence supports ethylene as a key factor in modulating plant responses to submergence stress. Meanwhile, there has been general consent that ethylene is not the only signal for the submergence-induced stem growth. In this study, we confirmed that hypoxia also promotes stem elongation in deepwater rice even in the absence of ethylene. As components of ethylene-independent hypoxia signalling, five HIGD (hypoxia-induced gene domain) protein genes were identified. Among the genes, OsHIGD2 showed the fastest and strongest induction by hypoxia as well as submergence. Co-expression analysis indicated that OsHIGD2 had a simultaneous expression pattern with fermentation-related genes, such as ADH1 (alcohol dehydrogenase 1) and PDC2 (pyruvate decarboxylase 2). Transient expression of OsHIGD2 in leaf epidermal cells of Nicotiana benthamiana provided evidence that the protein is localized to mitochondria. We further identified OsHIGD2-interacting proteins through the yeast two-hybrid assay using OsHIGD2 as bait. As a result, three mitochondrial proteins were discovered that function in the regulation of redox potential or reduction of protein damages caused by reactive oxygen species. In this report, we propose that OsHIGD2 is a mitochondrial protein which takes part in the early stage of hypoxia signalling by interacting with proteins that are related to oxygen utilization.
Department of Biology, Kunsan National University, Gunsan, 54150, Korea.
Soong-Taek
ST
Hwang
Department of Biology, Kunsan National University, Gunsan, 54150, Korea. choid@kunsan.ac.kr.
Dongsu
http://orcid.org/0000-0002-9967-1968
D
Choi
D000595:Amino Acid Sequence; D015687:Cell Hypoxia / Q000187:drug effects / Q000235:genetics; D005030:Ethylenes / Q000494:pharmacology; D018506:Gene Expression Regulation, Plant / Q000187:drug effects; D053263:Gene Regulatory Networks / Q000187:drug effects; D049452:Green Fluorescent Proteins / Q000378:metabolism; D005810:Multigene Family; D009928:Organ Specificity / Q000187:drug effects / Q000235:genetics; D012275:Oryza / Q000187:drug effects / Q000235:genetics / Q000254:growth & development* / Q000378:metabolism*; D010802:Phylogeny; D010940:Plant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D018547:Plant Stems / Q000187:drug effects / Q000254:growth & development* / Q000378:metabolism*; D011485:Protein Binding / Q000187:drug effects; D015398:Signal Transduction / Q000187:drug effects / Q000235:genetics; D013347:Subcellular Fractions / Q000378:metabolism; D020798:Two-Hybrid System Techniques; D014867:Water
D005030:Ethylenes; D010940:Plant Proteins; D014867:Water; D049452:Green Fluorescent Proteins; C036216:ethylene
Deepwater rice; Hypoxia; Hypoxia-induced gene domain; Mitochondria; Stem elongation; Submergence; Yeast two-hybrid screening