Analyzing the molecular mechanism of crop allelopathy by using differential proteomics
应用差异蛋白质组学方法分析作物化感作用的分子机理

In this paper,differential proteomic method was employed to study the molecular mechanism of crop allelopathy.The traditional QTL method was also compared.Experiments were conducted to determine the molecular mechanism of rice allelopathy under the biotic stresses induced by barnyardgrass(Echinochloa crusgalli L.).One of the two cloning tillers,obtained from single rice plant at 5 leaf-stage,was cultivated in pots with the addition of root exudates of either rice or barnyardgrass,respectively.At 7d,their leaf proteins were extracted for two-dimensional electrophoresis(2-DE).More than 800 proteins were resolved in each 2-DE gel and four leaf proteins displayed differentially.The four proteins showed high degree of reproducibility in the allelopathic rice response to the stresses of barnyardgrass.Individual protein spots were excised respectively from the 2-DE gel and measured by MALDI-TOF MS.Their Peptide Mass Finger Prints(PMF) were obtained.Further SWISS-PROT database search identified four matched proteins: peroxidase 2 precursor(POD),phenylalanine ammonia-lyase(PAL),3-hydroxy-3-methylglutaryl-coenzyme A reductase 3(HGMR) and thioredoxin M-type(Trx-m).The genes ecoding these four differential proteins were located on the chromosome 4,7,8,and 12 of rice.The QTLs of rice allelopathy varied with the donor plants,receiver plants and bioassay methods used.QTL analysis based on its approximate map locations and its small effects on phenotype proved to be inefficient.Advances in proteomics provide opportunities for accurate identification of positional,functional and expressional genes.By comparison of 2-DE protein patterns obtained from the treated and untreated plants,a set of stress-responsive proteins encoded by expressional candidate genes could be identified.Sequencing of these stressed-responsive proteins will then reveal the gene functions associated with the stress tolerant trait.The encoding genes will thus be regarded as both expressional and functional candidate genes.