Proteomic comparison of near-isogenic barley (Hordeum vulgare L.) germplasm differing in the allelic state of a major senescence QTL identifies numerous proteins involved in plant pathogen defense.
Senescence is the last developmental phase of plant tissues, organs and, in the case of monocarpic senescence, entire plants. In monocarpic crops such as barley, it leads to massive remobilization of nitrogen and other nutrients to developing seeds. To further investigate this process, a proteomic comparison of flag leaves of near-isogenic late- and early-senescing barley germplasm was performed. Protein samples at 14 and 21 days past anthesis were analyzed using both two-dimensional gel-based and label-free quantitative mass spectrometry-based ('shotgun') proteomic techniques. This approach identified >9000 barley proteins, and one-third of them were quantified. Analysis focused on proteins that were significantly (p < 0.05; difference ≥1.5-fold) upregulated in early-senescing line '10_11' as compared to late-senescing variety 'Karl', as these may be functionally important for senescence. Proteins in this group included family 1 pathogenesis-related proteins, intracellular and membrane receptors or co-receptors (NBS-LRRs, LRR-RLKs), enzymes involved in attacking pathogen cell walls (glucanases), enzymes with possible roles in cuticle modification, and enzymes involved in DNA repair. Additionally, proteases and elements of the ubiquitin-proteasome system were upregulated in line '10_11', suggesting involvement of nitrogen remobilization and regulatory processes. Overall, the proteomic data highlight a correlation between early senescence and upregulated defense functions. This correlation emerges more clearly from the current proteomic data than from a previously performed transcriptomic comparison of 'Karl' and '10_11'. Our findings stress the value of studying biological systems at both the transcript and protein levels, and point to the importance of pathogen defense functions during developmental leaf senescence.
Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, United States.
Katelyn E
KE
Mason
Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, United States; Proteomics, Metabolomics and Mass Spectrometry Facility, Montana State University, Bozeman, MT 59717, United States.
Jonathan K
JK
Hilmer
Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, United States.
Walid S
WS
Maaty
Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, United States.
Benjamin D
BD
Reeves
Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, United States.
Paul A
PA
Grieco
Chemistry and Biochemistry Department, Montana State University, Bozeman, MT 59717, United States; Proteomics, Metabolomics and Mass Spectrometry Facility, Montana State University, Bozeman, MT 59717, United States.
Brian
B
Bothner
Department of Plant Sciences and Plant Pathology, Montana State University, Bozeman, MT 59717, United States. Electronic address: fischer@montana.edu.
Andreas M
AM
Fischer
D000483:Alleles; D060467:Disease Resistance / Q000235:genetics; D015180:Electrophoresis, Gel, Two-Dimensional; D004591:Electrophoresis, Polyacrylamide Gel; D035264:Flowers / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D017343:Genes, Plant / Q000235:genetics; D001467:Hordeum / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D013058:Mass Spectrometry / Q000379:methods; D010935:Plant Diseases / Q000235:genetics; D018515:Plant Leaves / Q000235:genetics / Q000378:metabolism / Q000502:physiology; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D020543:Proteome / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics / Q000379:methods*; D040641:Quantitative Trait Loci / Q000235:genetics; D012639:Seeds / Q000235:genetics / Q000378:metabolism* / Q000502:physiology
D010940:Plant Proteins; D020543:Proteome
2D-DIGE proteomics; Barley (Hordeum vulgare L.); Defense; Plant-pathogen interaction; Senescence; Shotgun proteomics