Proteomics analysis of rice lesion mimic mutant (spl1) reveals tightly localized probenazole-induced protein (PBZ1) in cells undergoing programmed cell death.
Numerous reports have predicted/hypothesized a role for probenazole-induced protein (PBZ1) as a molecular marker in rice self-defense mechanism. However, the precise function of PBZ1 remains unknown. In the present study, we examined PBZ1 as a putative cell death marker in rice. For this, we focused our attention on a rice lesion mimic mutant (LMM), spotted leaf 1 ( spl1), which has been used to study the programmed cell death (PCD) phenomenon during lesion development in leaf. Using two-dimensional gel electrophoresis (2-DGE), 18 colloidal Coomassie brilliant blue stained protein spots were found to be differentially expressed in the leaves of spl1 mutant. After analysis of these spots by MALDI-TOF-MS, we identified the PBZ1 protein to be highly inducible in spl1. On the basis of these results, we proceeded to verify whether PBZ1 is highly expressed in the tissues undergoing PCD in rice. To do so, we performed immunoblot analysis and immunolocalization and used transgenic lines carrying the PBZ1 promoter fused with GFP. Results demonstrated that the expression levels and localizations of PBZ1 dramatically coincided with tissues undergoing PCD, namely, during leaf senescence, root aerenchyma formation, coleoptiles senescence, root cap, and seed aleurone layer. Furthermore, localization of the PBZ1 protein was also tightly correlated with TUNEL signal in the seed aleurone layer. As DNA fragmentation is a hallmark of PCD, this result clearly indicates a role for PBZ1 in rice tissues undergoing PCD. In conclusion, our results provide strong support for the hypothesis that PBZ1 is a molecular marker in rice defense response, and can serve as a novel potential marker for cell death/PCD in rice.
Kim
Sun Tae
ST
Environmental Biotechnology National Core Research Center, Division of Applied Life Science (BK21 program), Plant Molecular Biology and Biotechnology Research Center, Gyeongsang National University, Chinju 660-701, Korea.
Kim
Sang Gon
SG
Kang
Young Hyun
YH
Wang
Yiming
Y
Kim
Jae-Yean
JY
Yi
Nari
N
Kim
Ju-Kon
JK
Rakwal
Randeep
R
Koh
Hee-Jong
HJ
Kang
Kyu Young
KY
D017209:Apoptosis; D016922:Cellular Senescence; D002734:Chlorophyll / Q000378:metabolism; D018548:Cotyledon / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D053938:DNA Fragmentation; D015180:Electrophoresis, Gel, Two-Dimensional; D018506:Gene Expression Regulation, Plant; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D020287:In Situ Nick-End Labeling; D009154:Mutation; D012275:Oryza / Q000235:genetics / Q000378:metabolism*; D018515:Plant Leaves / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D010940:Plant Proteins / Q000235:genetics / Q000378:metabolism*; D018518:Plant Root Cap / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D030821:Plants, Genetically Modified; D011401:Promoter Regions, Genetic / Q000235:genetics; D011506:Proteins / Q000235:genetics; D020543:Proteome / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D040901:Proteomics / Q000379:methods; D012639:Seeds / Q000166:cytology / Q000235:genetics / Q000378:metabolism; D019032:Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization
C099062:PBZ1 protein, Oryza sativa; D010940:Plant Proteins; D011506:Proteins; D020543:Proteome; D002734:Chlorophyll; D049452:Green Fluorescent Proteins; C088014:spore photoproduct lyase